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general description the max2078 octal-channel ultrasound front-end is afully integrated bipolar, high-density octal-channel ultra- sound receiver optimized for low cost, high-channel count, high-performance portable and cart-based ultra- sound systems. the easy-to-use ic allows the user to achieve high-end 2d, pw, and cw doppler (cwd) imaging capability using substantially less space and power. the highly compact imaging receiver lineup, including low-noise amplifier (lna), variable-gain amplifier (vga), and anti-alias filter (aaf), achieves an ultra-low 2.4db noise figure at r s = r in = 200 at a very low 64.8mw per channel power dissipation. thefull imaging receiver channel has been optimized for second-harmonic imaging with -64dbfs second-har- monic distortion performance with a 1v p-p 5mhz output signal. the bipolar front-end has also been optimizedfor excellent low-velocity pw and color-flow doppler sensitivity with an exceptional near-carrier snr of 140dbc/hz at 1khz offset from a 5mhz 1v p-p output clutter signal.a fully integrated high-performance, programmable cwd beamformer is also included. separate i/q mixers for each channel are available for optimal cwd sensi- tivity in high-clutter environments, yielding an impres- sive near-carrier snr of 154dbc/hz at 1khz offset from a 1.25mhz 200mv p-p input clutter signal. the max2078 octal-channel ultrasound front-end isavailable in a small 10mm x 10mm, 68-pin thin qfn package with an exposed pad and is specified over a 0? to +70? temperature range. applications medical ultrasound imagingsonar features ? 8 full channels of lna, vga, aaf, and cwdmixers in a small, 10mm x 10mm tqfn package ? pin compatible with max2077 with lna, vga,and aaf in 10mm x 10mm tqfn variant ? ultra-low full-channel noise figure of 2.4db atr in = r s = 200 ? low output-referred noise of 23nv/ hz at 5mhz, 20db gain, yielding a broadband snr of 68db**for excellent second-harmonic imaging ? high near-carrier snr of 140dbc/hz at 1khzoffset from a 5mhz, 1v p-p output signal, and 20db of gain for excellent low-velocity pw andcolor-flow doppler sensitivity in a high-clutter environment ? ultra-low-power 64.8mw per full-channel (lna,vga, and aaf) normal imaging mode (234mw per channel in cwd mode) ? selectable active input-impedance matching of50 , 100 , 200 , and 1k ? wide input-voltage range of 330mv p-p in high lna gain mode and 550mv p-p in low lna gain mode ? integrated selectable 3-pole 9mhz, 10mhz,15mhz, and 18mhz butterworth aaf ? fast-recovery, low-power modes (< 2?) ? fully integrated, high dynamic range cwdbeamformer with near-carrier snr of 154dbc/hz at 1khz offset from a 1.25mhz, 200mv p-p input clutter signal max2078 octal-channel ultrasound front-end with cw doppler mixers ________________________________________________________________ maxim integrated products 1 5859606162 54555657 63 38 39 40 41 42 43 44 45 46 47 zf5 inc7 v cc1 thin qfn top view ci+ci- cq+ cq- v/c np cs din clk 5253 v cc2 out1+ in7in8 zf8 v cc2 inc8 v cc1 v ref vg- vg+clp gndgnd pd dout out3-out4+ out4- v cc1 lo+ lo-out5+ out5- out6+ out6- 35 36 37 out7+ out7- out8+ *ep *ep = exposed pad. ag gnd inc4 in4 zf4 inc6 in6 zf6 inc5 in5 inc3 in3 zf3 inc2 48 out3+ in2 64 v cc2 656667 inc1in1 zf1 68 zf2 2322212019 27262524 18 2928 323130 v cc2 out8- 3433 49 50 out2+out2- 51 + out1- 11 10 9 8 7 6 5 4 3 2 16 15 14 13 12 1 zf7 17 max2078 pin configuration ordering information 19-4570; rev 2; 9/11 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. + denotes a lead(pb)-free/rohs-compliant package. * ep = exposed pad. part temp range pin-package MAX2078CTK+ 0? to +70? 68 thin qfn-ep* ** when coupled with the max1437b adc. downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 2 _______________________________________________________________________________________ absolute maximum ratingsdc electrical characteristics ( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, clp = 0, pd = 0, no rf signals applied. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc_ to gnd .........................................................-0.3v to +5.5v v cc2 - v cc1 ......................................................................> -0.3v ci_, cq_ to gnd ....................................................-0.3v to +13v zf_, in_, ag to gnd ................................-0.3v to (v cc_ + 0.3v) inc_ ..............................................................................20ma dc v ref to gnd.............................................................-0.3v to +3v in_ to ag ...............................................................-0.6v to +0.6v out_, lo_, din, dout, vg_, np, cs , clk, pd, clp, v/c to gnd......................................-0.3v to v cc1 + 0.3v ci_, cq_, v cc_ , v ref analog and digital control signals must be applied in this order input differential voltage .............................2.0v p-p differential continuous power dissipation (t a = +70?) 68-pin tqfn (derated 40mw/? above +70?) ..................4w operating temperature range (note 1).................0? to +70? junction temperature ......................................................+150? storage temperature range .............................-40? to +150? lead temperature (soldering, 10s) .................................+300? soldering temperature (reflow) .......................................+260? parameter symbol conditions min typ max units 3.3v supply voltage v cc1 3.13 3.3 3.47 v 4.75v/5v supply voltage v cc2 4.5 4.75 5.25 v e xter nal refer ence v ol tag e rang ev ref (note 6) 2.475 2.525 v cmos input high voltage v ih applies to cmos control inputs 2.5 v cmos input low voltage v il applies to cmos control inputs 0.8 v cmos input leakage current i in t a = + 25 o c , ap p l i es to c m o s contr ol i np uts; 0 to 3.47v 10 ? data output high voltage dout_hi 10m load v cc1 v data output low voltage dout_lo 10m load 0 v dc electrical characteristics?ga mode( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, v/c = 1, clp = 0, pd = 0, no rf signals applied. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless other- wise noted.) (note 5) parameter symbol conditions min typ max units 4.75v /5v s up p l y s tand b y c ur r ent i_np_5v_tot np = 1, all channels 3.9 6 ma 3v supply standby current i_np_3v_tot np = 1, all channels 1.7 3 ma 4.75v/5v power-down current i_pd_5v_tot pd = 1, all channels 0.4 10 ? note 2: junction temperature t j = t c + ( jc x v cc x i cc ). this formula can only be used if the component is soldered down to a printed circuit board pad containing multiple ground vias to remove the heat. the junction temperature must not exceed 150?. note 3: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial . note 4: junction temperature t j = t a + ( ja x v cc x i cc ), assuming there is no heat removal from the exposed pad. the junction temperature must not exceed 150?. 64 tqfn junction-to-ambient thermal resistance ( ja )........20?/w junction-to-case thermal resistance ( jc )............0.5?/w package thermal chracteristics (notes 2, 3, 4) downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers _______________________________________________________________________________________ 3 dc electrical characteristics?w mode( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, pd = 0, clp = 0, v/c = 0, no rf signals applied. ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) parameter symbol conditions min typ max units reference current i ref 82.7 ? m i xer lv d s lo inp ut c om m on- m od e v ol tag e v_lvds_cm lo+ and lo- 1.25 ?.2 v lvds lo differential input voltage v_lvds_dm common-mode input voltage = 1.25v (note 7) 200 700 mv p-p lvds lo input common-mode current i_lvds_cm current out of each pin, v_lvds_cm = 1.25v 130 ? lvds lo differential input resistance r_dm_lvds (note 8) 4 k power-down mode 4.75v/5v supply current per channel i_c_5v_p pd = 1 0.6 10 ? 3.3v supply current per channel i_c_3_3v_p pd = 1 0.1 10 ? low-power mode 4.75v/5v supply current per channel i_c_5v_l clp = 1 27 30 ma 3.3v supply current per channel i_c_3_3v_l clp = 1 0.4 0.95 ma 11v supply current per channel i_c_11v_l clp = 1 6.8 8.4 ma on-chip power dissipation (all 8 channels) pdis_fp_tot_l clp = 1 1.44 1.7 w normal power mode 4.75v/5v supply current per channel i_c_5v_n 31 34 ma 3.3v supply current per channel i_c_3_3v_n 0.4 0.95 ma 11v supply current per channel i_c_11v_n 11.3 13 ma on-chip power dissipation (all 8 channels) pdis_fp_tot_n (note 9) 1.87 2.2 w dc electrical characteristics?ga mode (continued)( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, v/c = 1, clp = 0, pd = 0, no rf signals applied. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless other- wise noted.) (note 5) parameter symbol conditions min typ max units 3v power-down current i_pd_3v_tot pd = v cc1 , all channels 0.3 10 ? 3v supply current per channel i_3v_nm total i divided by 8, vg+ - vg- = -2v 11 16 ma 4.75v/5v supply current per channel i_5v_nm total i divided by 8 6.0 8.3 ma dc power per channel p_nm 64.8 92.3 mw differential analog control voltagerange vgain_rang vg+ - vg- ? v common-mode voltage fordifference analog control vgain_comm (vg+ + vg-)/2 1.65 ?% v source/sink current for gain controlpins i_acontrol per pin ?.6 ?.3 a reference voltage input v ref 2.475 2.525 v reference current i ref all channels 9.7 13 ? output common-mode level v cmo 1.73 v downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 4 _______________________________________________________________________________________ ac electrical characteristics ( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, pd = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db, d45/d44 = 1/1 (f c = 18mhz), f rf = f lo /16 = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf, r l = 1k differential, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) parameter conditions min typ max units v/c stepped from 0 to 1, dc stable within 10% 1 mode select response time(note 10) v/c stepped from 1 to 0, dc stable within 10% 1 ? high gain maximum input-voltage range high lna gain d43/d42/d41/d40 = 1/0/1/0 0.33 v p-p differential low gain maximum input-voltagerange low lna gain d43/d42/d41/d40 = 0/0/0/1 0.6 v p-p differential ac electrical characteristics?ga mode( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, v/c = 1, np = 0, pd = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf, r l = 1k differential, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) parameter conditions min typ max units d42/d41/d40 = 0/0/0, r in = 50 ? 47.5 50 60 d42/d41/d40 = 0/0/1, r in = 100 ? 90 100 110 d42/d41/d40 = 0/1/0, r in = 200 ? 180 200 220 input impedance d42/d41/d40 = 0/1/1, r in = 1000 ? , f rf = 2mhz 700 830 1000 ? r s = r in = 50 ? , vg+ - vg- = +3v 4.5 r s = r in =100 ? , vg+ - vg- = +3v 3.4 r s = r in = 200 ? , vg+ - vg- = +3v 2.4 noise figure r s = r in = 1000 ? , vg+ - vg- = +3v 2.1 db low-gain noise figure d43/d42/d41/d40 = 0/0/0/1, lna gain = 12.5db,r s = r in = 200 ? , vg+ - vg- = +3v 3.9 db input-referred noise voltage d43/d42/d41/d40 = 1/1/1/0 0.9 nv/ hz input-referred noise current d43/d42/d41/d40 = 1/1/1/0 2.1 pa/ hz m axi m um gai n, h i g h g ai n s etti ng vg+ - vg- = +3v 41 42.8 45 db minimum gain, high gain setting vg+ - vg- = -3v 8.5 10 11 db maximum gain, low gain setting d43/d42/d41/d40 = 0/0/0/1, vg+ - vg- = +3v 35 36.8 38 db minimum gain, low gain setting d43/d42/d41/d40 = 0/0/0/1, vg+ - vg- = -3v 2.5 4 6 db d45/d44 = 0/0, f c = 9mhz 9 d45/d44 = 0/1, f c = 10mhz 10 d45/d44 = 1/0, f c = 15mhz 15 anti-aliasing filter 3db cornerfrequency d45/d44 = 1/1, f c = 18mhz 18 mhz gain range vg+ - vg- = -3v to +3v 33 db downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers _______________________________________________________________________________________ 5 ac electrical characteristics?ga mode (continued)( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, v/c = 1, np = 0, pd = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf, r l = 1k differential, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) parameter conditions min typ max units measured at t a = +25 o c, v vg + - v vg - = -2v ?.4 measured at t a = +25 o c, v vg + - v vg - = 0v ?.4 absolute gain error measured at t a = +25 o c, v vg + - v vg - = +2v ?.4 db v vg + - v vg - = -3v (vga minimum gain), gain ratio with 330mv p-p /50mv p-p input tones 1.4 input gain compression lna low gain = 12.5db, v vg + - v vg - = -3v (vga minimum gain), gain ratio with 600mv p-p /50mv p-p 0.8 db gain step up (v in = 5mv p-p , gain changed from 10db to 44db, settling time is measured within 1db final value) 1.4 vga gain response time g ai n step d ow n ( v i n = 5m v p - p , g ai n chang ed fr om 44d b to 10d b, settl i ng ti m e i s m easur ed w i thi n 1d b fi nal val ue) 1.6 ? vga output offset under pulsedoverload overdrive is ?0ma in clamping diodes, gain at 30db,16 pulses at 5mhz, repetition rate 20khz; offset is measured at output when rf duty cycle is off 180 mv small-signal output noise 20db of gain, v vg + - v vg - = -0.85v, no input signal 23 nv/ hz large-signal output noise 20db of gain, v vg + - v vg - = -0.85v, f rf = 5mhz, f noise = f rf + 1khz, v out = 1v p-p differential 35 nv/ hz v in = 50mv p-p , f rf = 2mhz, v out = 1v p-p -67 second harmonic (hd2) v in = 50mv p-p , f rf = 5mhz, v out = 1v p-p -64.2 dbc high-gain im3 distortion v in = 50mv p-p , f rf1 = 5mhz, f rf2 = 5.01mhz, v out = 1v p-p (note 11) -52 -61 dbc low-gain im3 distortion d43/d42/d41/d40 = 0/0/0/1 (r in = 200 , lna gain = 12.5db),v in = 100mv p-p , f rf1 = 5mhz, f rf2 = 5.01mhz, v out = 1v p-p (note 11) -50 -60 dbc standby mode power-upresponse time gain set for 26db, f rf = 5mhz, v out = 1v p-p , settled with in 1db from transition on np pin 2.1 ? standby mode power-downresponse time to reach dc current target ?0% 2.0 ? power-up response time gain set for 28db, f rf = 5mhz, v out = 1v p-p , settled within 1db from transition on pd 2.7 ms power-down response time gain set for 28db, f rf = 5mhz, dc power reaches 6mw/channel, from transition on pd 5n s adjacent channel crosstalk v out = 1v p-p differential, f rf = 10mhz, 28db of gain -58 dbc nonadjacent channel crosstalk v out = 1v p-p differential, f rf = 10mhz, 28db of gain -71 dbc phase matching betweenchannels gain = 28db, v vg + - v vg - = 0.4v, v out = 1v p-p , f rf = 10mhz ?.2 d eg r ees downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 6 _______________________________________________________________________________________ ac electrical characteristics?ga mode (continued)( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, v/c = 1, np = 0, pd = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf, r l = 1k differential, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) ac electrical characteristics?w mode( typical application circuit , v/c = 0, pd = 0, np = 0, clp = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), f rf = f lo /16 = 5mhz, r s = 200 , ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors, the rise/fall time of the lvds clock driving the lo_ is required to be 0.5ns, reference noise less than 10nv/ hz from 1khz to 20mhz (note 12). typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) parameter conditions min typ max units cw doppler mixer mixer rf frequency range 0.9 7.6 mhz lo frequency range lo+ and lo- 16 120 mhz mixer output frequency range dc 100 khz full-power mode noise figure no carrier 3.4 db noise figure at 100mv p-p input 100mv p-p at input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset 3.6 db noise figure at 200mv p-p input 200mv p-p at input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset 4.1 db snr at 100mv p-p input 100mv p-p at input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset -148.3 dbc/hz snr at 200mv p-p input 200mv p-p at input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset -153.8 dbc/hz parameter conditions min typ max units 3v supply modulation ratio gain = 28db, v vg+ - v vg - = 0.4v, v out = 1v p-p , f rf = 5mhz, f mod = 1khz, v mod = 50mv p-p , ratio of output sideband at 5.001mhz, 1v p-p -73 dbc 4.75v/5v supply modulationratio gain = 28db, v vg+ - v vg - = 0.4v, v out = 1v p-p , f rf = 5mhz, f mod = 1khz, v mod = 50mv p-p , ratio of output sideband at 5.001mhz, 1v p-p -82 dbc gain control lines common-mode rejection ratio gain = 28db, v vg+ - v vg - = 0.4v, f mod = 5mhz, v mod = 50mv p-p , v out = 1.0v p-p -74 dbc overdrive phase delay v vg+ - v vg - = -3v, delay between v in = 300mv p-p and v in = 30mv p-p differential 5n s output impedance differential 100 downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers _______________________________________________________________________________________ 7 ac electrical characteristics?w mode (continued)( typical application circuit , v/c = 0, pd = 0, np = 0, clp = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), f rf = f lo /16 = 5mhz, r s = 200 , ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors, the rise/fall time of the lvds clock driving the lo_ is required to be 0.5ns, reference noise less than 10nv/ hz from 1khz to 20mhz (note 12). typical values are at v cc1 = 3.3v, v cc2 = 4.75v, t a = +25?, unless otherwise noted.) (note 5) parameter conditions min typ max units two-tone intermodulation imd3at 100mv f rf1 = 5mhz, 0.1v p-p, f rf2 = 5.01mhz at -25dbc, f lo = 80mhz (note 11) -50 -55 dbc two-tone intermodulation imd3at 200mv f rf1 = 5mhz, 0.2v p-p , f rf2 = 5.01mhz at -25dbc, f lo = 80mhz (note 11) -48.5 dbc mixer output-voltagecompliance valid voltage range (ac + dc) on summed mixer outputpins 4.5 12 v channel-to-channel phasematching measured under zero beat conditions, v rf = 100mv p-p , f rf = 5mhz, f lo = 80mhz (note 13) ?.4 d eg r ees channel-to-channel gainmatching measured under zero beat conditions, v rf = 100mv p-p , f rf = 5mhz, f lo = 80mhz (notes 13, 14) ?.2 db f rf = 0.9mhz, f lo /16 = 1mhz 19 23 26 transconductance calculated from lna input voltageand twice the i or q current f rf = 7.6mhz, f lo /16 = 7.5mhz 19 22.5 26 ms low-power mode (clp = 1) noise figure no carrier 3.2 db noise figure at 100mv p-p input 100mv p-p on input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset 3.5 db noise figure at 200mv p-p input 200mv p-p on input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset 4.3 db snr at 100mv p-p input 100mv p-p on input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset -148.2 dbc/hz snr at 200mv p-p input 200mv p-p on input, f rf = f lo /16 = 1.25mhz, measured at 1khz offset -153.6 dbc/hz two-tone intermodulation imd3 f rf1 = 5mhz, 0.1v p-p , f rf2 = 5.01mhz at -25dbc, f lo = 80mhz (note 11) -44 dbc m i xer o utp ut- v ol tag e c om p l i ance v al i d vol tag e r ang e on sum m ed m i xer outp ut p i ns ( n ote 12) 4.5 12 v f rf = 1.1mhz, f lo /16 = 1mhz 19 21.5 26 transconductance (note 16) calculated from lna input voltageand twice the i or q current f rf = 7.6mhz, f lo /16 = 7.5mhz 19 21.5 26 ms downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 8 _______________________________________________________________________________________ ac electrical characteristics?erial peripheral interface(dout loaded with 60pf and 10m , 2ns rise and fall edges on clk.) parameter symbol conditions min typ max units clock speed 10 mhz mininimum data-to-clock setuptime t cs 5n s mininimum data-to-clock holdtime t ch 0n s mininimum clock-to- cs setup time t es 5n s cs positive mininimum pulse width t ew 1n s mininimum clock pulse width t cw 2n s mininimum cs high to mixer clock on t mix cs 2n s note 5: minimum and maximum limits at t a = +25? and +70? are guaranteed by design, characterization, and/or production test. note 6: noise performance of the device is dependent on the noise contribution from v ref . use a low-noise supply for v ref . note 7: note that the lvds cwd lo clocks are dc-coupled. this is to ensure immediate synchronization when the clock is firstturned on. an ac-coupled lo is problematic in that the rc time constant associated with the coupling capacitors and the input impedance of the pin causes a period of time (related to the rc time constant) when the dc level on the chip side of the capacitor is outside the acceptable common-mode range and the lo swing does not excede both of the logic thresh- olds required for proper operation. this problem associated with ac-coupling causes an inability to ensure synchronization among beamforming channels. the lvds signal is terminated differentially with an external 100 resistor on the board. note 8: an external 100 resistor terminates the lvds differential signal path. note 9: total on-chip power dissipation is calculated as p diss = v cc1 x i cc1 + v cc2 x i cc2 + v ref x i ref + [11v - (i 11v /4) x 162] x i 11v . note 10: this response time does not include the cw output highpass filter. when switching to vga mode, the cw outputs stopdrawing current and the output voltage goes to the rail. if a highpass filter is used, the recovery time may be excessive and a switching network is recommended, as shown in the applications information section. note 11: see the ultrasound-specific imd3 specification section. note 12: the reference input noise is given for 8 channels, knowing that the reference-noise contributions are correlated in all 8channels. if more channels are used, the reference noise must be reduced to get the best noise performance. note 13: channel-to-channel gain and phase matching measured on 30 pieces during engineering characterization at room tem-perature. each mixer is used as a phase detector and produces a dc voltage in the iq plane. the phase is given by the angle of the vector drawn on that plane. multiple channels from multiple parts are compared to each other to produce the phase variation. note 14: voltage gain is measured by subtracting the output-voltage signal from the input-voltage signal. the output-voltage signalis obtained by taking the differential cw i output and summing it in quadrature with the differential cw q output. the input voltage is defined as the differential voltage applied to the cw input pins. note 15: mixer output-voltage compliance is the range of acceptable voltages allowed on the cw mixer outputs. note 16: transconductance is defined as the quadrature-combined cw differential output current at baseband divided by themixer? input voltage. downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers _______________________________________________________________________________________ 9 gain vs. differential analog control voltage max2078 toc01 control voltage (v) gain (db) 2 1 0 -1 -2 15 25 35 45 5 -3 3 complex input impedance magnitude vs. frequency max2078 toc02 frequency (mhz) input impedance ( ) 15 10 5 200 400 600 800 1000 0 02 0 1k 100 200 50 gain error histogram max2078 toc03 gain error (db) % units 5 10 15 20 25 0 -0.175-0.125 -0.075 -0.025 0.0250.075 0.125 0.175 0.225 0.275 gain = 20db output-referred noise vs. gain max2078 toc04 gain (db) noise (nv/ hz) 35 26 17 30 60 90 120 150 180 0 8 44 input-referred noise vs. gain max2078 toc05 gain (db) 35 26 17 2 3 4 5 61 8 44 noise (nv/ hz) second-harmonic distortion vs. gain max2078 toc06 gain (db) hd2 (dbc) 38 32 26 -80 -70 -60 -50 -40 -30-90 20 44 v out = 1v p-p f rf = 10mhz f rf = 2mhz f rf = 5mhz typical operating characteristics ( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, pd = 0, clp = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = f lo /16 = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf , r l = 1k differential, r s = 200 , ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors, the rise/fall time of the lvds clock driving the lo_ is required to be 0.5ns, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 5v, t a = +25?, unless otherwise noted.) _______________________________________________________________________________________ 9 downloaded from: http:///
max2078 typical operating characteristics (continued) ( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, pd = 0, clp = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = f lo /16 = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf , r l = 1k differential, r s = 200 , ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors, the rise/fall time of the lvds clock driving the lo_ is required to be 0.5ns, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 5v, t a = +25?, unless otherwise noted.) octal-channel ultrasound front-end with cw doppler mixers 10 ______________________________________________________________________________________ third-harmonic distortion vs. gain max2078 toc07 gain (db) hd3 (dbc) 38 32 26 -80 -70 -60 -50 -40 -30-90 20 44 v out = 1v p-p f rf = 10mhz f rf = 2mhz f rf = 5mhz two-tone ultrasound-specific imd3 vs. gain max2078 toc08 gain (db) imd3 (dbc) 38 32 26 -70 -50 -30 -10-90 20 44 v out = 1v p-p f rf = 10mhz f rf = 2mhz f rf = 5mhz second- and third-harmonic distortion vs. v out_p-p max2078 toc09 v out_p-p (v) hd2 and hd3 (dbc) 0.8 0.6 0.4 0.2 -80 -70 -60 -50-90 01 . 0 gain = 26dbf rf = 5mhz hd2 hd3 second- and third-harmonic distortion vs. frequency max2078 toc10 frequency (mhz) hd2 and hd3 (dbc) 15 10 5 -70 -60 -50 -40 -30-80 02 0 v out = 1v p-p gain = 26db hd2 hd3 second- and third-harmonic distortion vs. differential output resistance max2078 toc11 resistance ( ) hd2 and hd3 (dbc) 900 800 700 600 500 400 300 -80 -70 -60 -50 -40 -30-90 200 1000 v out = 1v p-p gain = 26dbf rf = 5mhz hd2 hd3 second- and third-harmonic distortion vs. differential output load capacitance max2078 toc12 capacitance (pf) hd2 and dh3 (dbc) 80 60 40 20 -80 -70 -60 -50 -40 -30-90 01 0 0 v out = 1v p-p gain = 26dbf rf = 5mhz hd2 hd3 downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 11 large-signal bandwidth vs. frequency max2078 toc16 frequency (mhz) gain (db) 10 -10 0 10 20 30 -20 1 100 v out = 1v p-p gain = 20db 18mhz 15mhz 10mhz 9mhz common-mode output voltage vs. gain max2078 toc17 gain (db) common-mode output voltage (v) 35 26 17 1.6 1.7 1.8 1.91.5 8 44 differential output impedance vs. frequency frequency (mhz) real component ( ) imaginary component ( ) 40 30 20 10 60 120 180 6040 20 0 80 0 05 0 max2078 toc18 real imaginary ______________________________________________________________________________________ 11 typical operating characteristics (continued) ( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, pd = 0, clp = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = f lo /16 = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf , r l = 1k differential, r s = 200 , ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors, the rise/fall time of the lvds clock driving the lo_ is required to be 0.5ns, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 5v, t a = +25?, unless otherwise noted.) two-tone ultrasound-specific imd3 vs. frequency max2078 toc13 frequency (mhz) imd3 (dbc) 15 10 5 -60 -40 -20 0 -80 02 0 v out = 1v p-p gain = 26db adjacent channel-to-channel crosstalk vs. gain max2078 toc14 gain (db) crosstalk (dbc) 35 26 17 -65 -60 -55 -50-70 84 4 v out = 1v p-p f rf = 10mhz adjacent channel 1 adjacent channel 2 adjacent channel-to-channel crosstalk vs. frequency max2078 toc15 frequency (mhz) crosstalk (dbc) 10 -60 -30 0 -90 11 0 0 v out = 1v p-p gain = 20db adjacent channel 1 adjacent channel 2 downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 12 ______________________________________________________________________________________ lna overload recovery time (v in = 500mv p-p for 1 s to 100mv p-p for 1 s and back to 500mv p-p for 1 s, gain = 10db) time (ns) output (v) 1500 500 1000 -0.25 0.25 0.75 1.25 -0.75 0 2000 max2078 toc19 input (v) 0-0.5 -1.0 -1.5 0.5 input output output (v) -1 0 1 2 3 -2 vga overload recovery time (v in = 40mv p-p for 1 s to 4mv p-p for 1 s and back to 40mv p-p for 1 s, gain = 42.5db) max2078 toc20 input (v) 0 -0.05 -0.10 -0.15 0.05 output time (ns) 1500 500 1000 0 2000 input overdrive phase delay vs. frequency max2078 toc21 frequency (mhz) phase delay (ns) 9 18 27 36 45 0 15 5 10 02 0 gain = 10db input = 300mv p-p input = 30mv p-p group delay vs. frequency max2078 toc22 group delay (ns) 25 35 45 15 frequency (mhz) 15 5 10 02 0 gain = 10db gain = 20db gain = 40db gain = 30db cw imd3 vs. frequency max2078 toc23 frequency (mhz) cw imd3 (dbc) 6 4 2 -60 -56 -52 -48-64 0 8 v in = 100mv p-p input-referred noise vs. input clutter voltage max2078 toc24 input clutter voltage (mv p-p ) 150 100 50 1.32 1.36 1.40 1.44 1.481.28 0 200 noise (nv/ hz) f clutter = 1.25mhz offset = 1khz low-power mode normal power mode typical operating characteristics (continued) ( typical application circuit , v ref = 2.475v to 2.525v, v cc1 = 3.13v to 3.47v, v cc2 = 4.5v to 5.25v, t a = 0? to +70?, v gnd = 0v, np = 0, pd = 0, clp = 0, d43/d42/d41/d40 = 1/0/1/0 (r in = 200 , lna gain = 18.5db), d45/d44 = 1/1 (f c = 18mhz), f rf = f lo /16 = 5mhz, capacitance to gnd at each of the vga differential outputs is 25pf, differential capacitance across vga outputs is 15pf , r l = 1k differential, r s = 200 , ci_, cq_ pulled up to 11v through four separate 0.1% 162 resistors, the rise/fall time of the lvds clock driving the lo_ is required to be 0.5ns, reference noise less than 10nv/ hz from 1khz to 20mhz, dout loaded with 10m and 60pf. typical values are at v cc1 = 3.3v, v cc2 = 5v, t a = +25?, unless otherwise noted.) downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 13 pin description pin name function 1 in2 channel 2 input 2 inc2 c hannel 2 c l am p inp ut. c onnect to a coup l i ng cap aci tor . s ee the typ i cal ap p l i cati on c i r cui t for d etai l s. 3 zf3 channel 3 active impedance matching line. ac-couple to source with a 10nf capacitor. 4 in3 channel 3 input 5 inc3 c hannel 3 c l am p inp ut. c onnect to a coup l i ng cap aci tor . s ee the typ i cal ap p l i cati on c i r cui t for d etai l s. 6 zf4 channel 4 active impedance matching line. ac-couple to source with a 10nf capacitor. 7 in4 channel 4 input 8 inc4 channel 4 clamp input. connect to the input coupling capacitor. see the typical application circuit for details. 9, 28, 31 gnd ground 10 ag ac ground. connect a low-esr 1? capacitor to ground. 11 zf5 channel 5 active impedance matching line. ac-couple to source with a 10nf capacitor. 12 in5 channel 5 input 13 inc5 c hannel 5 c l am p inp ut. c onnect to a coup l i ng cap aci tor . s ee the typ i cal ap p l i cati on c i r cui t for d etai l s. 14 zf6 channel 6 active impedance matching line. ac-couple to source with a 10nf capacitor. 15 in6 channel 6 input 16 inc6 c hannel 6 c l am p inp ut. c onnect to a coup l i ng cap aci tor . s ee the typ i cal ap p l i cati on c i r cui t for d etai l s. 17 zf7 channel 7 active impedance matching line. ac-couple to source with a 10nf capacitor. 18 in7 channel 7 input 19 inc7 channel 7 clamp input. connect to the input coupling capacitor. see the typical application circuit for details. 20 zf8 channel 8 active impedance matching line. ac-couple to source with a 10nf capacitor. 21 in8 channel 8 input 22 inc8 c hannel 8 c l am p inp ut. c onnect to a coup l i ng cap aci tor . s ee the typ i cal ap p l i cati on c i r cui t for d etai l s. 23, 33, 53, 64 v cc2 4.75v power supply. connect to an external 4.75v power supply. connect all 4.75v supply pinstogether externally and bypass with 100nf capacitors as close as possible to the pin. 24 v ref external 2.5v reference supply. connect to a low-noise power supply. bypass to gnd with a 0.1?capacitor as close as possible to the pins. note that noise performance of the device is dependent on the noise contribution from v ref . use a low-noise supply for v ref . 25, 44, 63 v cc1 3.3v power supply. connect to an external 3.3v power supply. connect all 3.3v supply pins togetherexternally and bypass with 100nf capacitors as close as possible to the pin. 26 vg+ 27 vg- vga analog gain control differential input. set the differential voltage to -3v for minimum gain and to+3v for maximum gain. 29 clp cw low-power mode select input. drive clp high to place cw mixers in low-power mode. 30 pd power-down mode select input. set pd to v cc1 to place the entire device in power-down mode. drive pd low for normal operation. this mode overrides the standby mode. 32 dout serial port data output. data output for ease of daisy-chain programming. the level is 3.3v cmos. 34 out8- channel 8 negative differential output 35 out8+ channel 8 positive differential output 36 out7- channel 7 negative differential output downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 14 ______________________________________________________________________________________ pin description (continued) pin name function 37 out7+ channel 7 positive differential output 38 out6- channel 6 negative differential output 39 out6+ channel 6 positive differential output 40 out5- channel 5 negative differential output 41 out5+ channel 5 positive differential output 42 lo- 43 lo+ differential local oscillator input. lo is divided in the beamformer. 45 out4- channel 4 negative differential output 46 out4+ channel 4 positive differential output 47 out3- channel 3 negative differential output 48 out3+ channel 3 positive differential output 49 out2- channel 2 negative differential output 50 out2+ channel 2 positive differential output 51 out1- channel 1 negative differential output 52 out1+ channel 1 positive differential output 54 clk serial port clock input (positive edge triggered). 3.3v cmos. clock input for programming the serial shift registers. 55 din serial port data input. 3.3v cmos. data input to program the serial shift registers. 56 cs serial port chip select input. 3.3v cmos. used to store programming bits in registers, as well as incw mode, synchronizing all channel phases (on a rising edge). 57 np vga standby mode select input. set np to 1 to place the entire device in standby mode. overridessoft channel shutdown in serial shift register, but not general power-down (pd). 58 v/c vga/cw mode select input. set v/c to a logic-high to enable the vgas and disable cw mode. setv/c to a logic-low to enable the cw mixers and disable the vga mode. 59 cq- 8-channel cw negative quadrature output. connect to an external 11v power supply with a 162 external pullup resistor. 60 cq+ 8-channel cw positive quadrature output. connect to an external 11v power supply with a 162 external pullup resistor. 61 ci- 8-channel cw negative in-phase output. connect to an external 11v power supply with a 162 external pullup resistor. 62 ci+ 8-channel cw positive in-phase output. connect to an external 11v power supply with a 162 external pullup resistor. 65 zf1 channel 1 active impedance matching line. ac-couple to source with a 10nf capacitor. 66 in1 channel 1 input 67 inc1 channel 1 clamp input. connect to the input coupling capacitor. see the typical application circuits for details. 68 zf2 channel 2 active impedance matching line. ac-couple to source with a 10nf capacitor. ? p exposed pad. internally connected to ground. connect to a large ground plane using multiple vias to maximize thermal and electrical performance. not intended as an electrical connection point. downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 15 block diagram max2078 anti-alias out1+out1- ci+ ci- cq+ v cc2 v cc1 lo+ lo- clk din cs np v/c cq- zf1 v cc2 v cc1 in1 inc1 anti-alias out2+out2- zf2 in2 inc2 lna vga anti-alias out3+out3- zf3 in3 inc3 lna vga anti-alias out4+out4- zf4 in4 inc4 gnd zf8 lna vga anti-alias out5+out5- zf5 ag in5 inc5 lna vga anti-alias out6+out6- zf6 in6 inc6 lna vga anti-alias out7+out7- zf7 in7 inc7 in8 lna vga anti-alias out8+out8- inc8 lna vga lna vga downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 16 ______________________________________________________________________________________ detailed description the max2078 is a high-density, octal-channel ultra-sound receiver optimized for low cost, high-channel count, high-performance portable and cart-based ultra- sound applications. the integrated octal lna, vga, aaf, and programmable cwd beamformer offer a complete multi-specialty, ultrasound receiver solution. imaging path dynamic range has been optimized for exceptional second-harmonic performance. the com- plete imaging receive channel exhibits an exceptional 68dbfs** snr at 5mhz. the bipolar front-end has also been optimized for exceptionally low near-carrier mod- ulation noise for exceptional low-velocity pulsed and color-flow doppler sensitivity under high-clutter condi- tions, achieving an impressive near-carrier snr of 140dbc/hz at 1khz offset from a v out = 1v p-p , 5mhz clutter signal. the max2078 also integrates an octal quadraturemixer array and programmable lo phase generators for a complete continuous-wave doppler (cwd) beam- forming solution. separate mixers for each channel are available for optimal cwd sensitivity, yielding an impressive snr of 154dbc/hz at 1khz offset from a 200mv p-p , 1.25mhz input signal. the lo phase selec- tion for each channel is programmed using a digitalserial interface and a single high-frequency clock. the serial interface is designed to allow multiple devices to be easily daisy-chained to minimize program interface wiring. the outputs of the mixers are summed into sin- gle i and q differential current outputs. modes of operation the max2078 requires programming before it can beused. the operating modes are controlled by 47 pro- gramming bits. tables 1 and 2 show the functions of these programming bits. bit name description d40, d41, d42 input impedance programming d43 lna gain (d43 = 0 is low gain) d44, d45 anti-alias filter f c programming d46 don? care d0?39 beamformer programming, from channel 1 to 8 table 1. summary of programming bits d46 d45 d44 d43 d42 d41 d40 mode xxx1000 r in = 50 , lna gain = 18.5db xxx1001 r in = 100 xxx1010 r in = 200 xxx1011 r in = 1000 xxx0000 r in = 100 , lna gain = 12.5db xxx0001 r in = 200 xxx0010 r in = 400 xxx0011 r in = 2000 x x x 1 1 x x open feedback x00xxxx f c = 9mhz x01xxxx f c = 10mhz x10xxxx f c = 15mhz x11xxxx f c = 18mhz table 2. logic functions of programming bits x = don? care. ** when coupled with the max1437b adc. downloaded from: http:///
low-noise amplifier (lna) the max2078? lna is optimized for excellent dynamicrange and linearity performance characteristics, making it ideal for ultrasound imaging applications. when the lna is placed in low-gain mode, the input resistance (r in ), being a function of the gain a (r in = r f /(1 + a)), increas- es by a factor of approximately 2. consequently, theswitches that control the feedback resistance (r f ) have to be changed. for instance, the 100 mode in high gain becomes the 200 mode in low gain (see table 2). variable-gain amplifier (vga) the max2078? vgas are optimized for high linearity,high dynamic range, and low output-noise performance, all of which are critical parameters for ultrasound imaging applications. each vga path includes circuitry for adjust- ing analog gain, as well as an output buffer with differen- tial output ports (out_+, out_-) for driving adcs. see the high-level cw mixer and programmable beamformer functional diagram for details. the vga gain can be adjusted through the differentialgain control input vg+ and vg-. set the differential gain control input voltage at -3v for minimum gain and +3v for maximum gain. the differential analog control common- mode voltage is 1.65v (typ). overload recovery the device is also optimized for quick overload recoveryfor operation under the large input signal conditions that are typically found in ultrasound input buffer imaging applications. see the typical operating characteristics for an illustration of the rapid recovery time from a trans-mit-related overload. octal continuous-wave (cw) mixer the max2078 cw mixers are designed using an activedouble-balanced topology. the mixers achieve high dynamic range and high linearity performance, with exceptionally low thermal and jitter noise, ideal for ultra- sound cwd signal reception. the octal quadrature mixer array provides noise performance of 154dbc/hz at 1khz offset from a 1.25mhz, 200mv p-p input clutter signal and a two-tone third-order ultrasound-specificintermodulation product of -48.5dbc (typ). see the ultrasound-specific imd3 specification section. the octal array exhibits quadrature and in-phase differ-ential current outputs (cq+, cq-, ci+, ci-) to produce the total cwd beamformed signal. the maximum differ- ential current output is typically 3ma p-p and the mixer- output compliance voltage ranges from 4.5v to 12v. max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 17 high-level cw mixer and programmable beamformer functional diagram channel 1 i/q phase divider selector channel 2 i/q phase divider selector 5 5 5-bit sr 5-bit sr din cs clk dout clp pd lo+ lo- cw_qout cw_iout cw_in1 cw_in3cw_in2 cw_in5cw_in4 cw_in7cw_in6 cw_in8 iq iq channel 3 i/q phase divider selector 5 5-bit sr iq channel 4 i/q phase divider selector 5 5-bit sr iq channel 5 i/q phase divider selector 5 5-bit sr iq channel 6 i/q phase divider selector 5 5-bit sr iq channel 7 i/q phase divider selector 5 5-bit sr iq channel 8 i/q phase divider selector 5 5-bit sr iq max2078 downloaded from: http:///
max2078 each mixer can be programmed to 1 of 16 phases;therefore, 4 bits are required for each channel for pro- gramming. each cw channel can be programmed to an off state by setting bit di to 1. the power-down mode (pd) line overrides this soft shutdown. after the serial shift registers have been programmed, the cs signal, when going high, loads the phase infor- mation in the form of 5 bits per channel into the i/qphase divider/selectors. this presets the dividers, selecting the appropriate mixer phasing. see table 3 for mixer phase configurations. cw mixer output summation the outputs from the octal-channel mixer array aresummed internally to produce the total cwd summed beamformed signal. the octal array produces eight differential quadrature (q) outputs and eight differentialin-phase (i) outputs. all quadrature and in-phase out- puts are summed into single i and q differential current outputs (cq+, cq-, ci+, ci-). lo phase select the lo phase dividers can be programmed throughthe shift registers to allow for 16 quadrature phases for a complete cw beamforming solution. synchronization figure 1 illustrates the serial programming of the eightindividual channels through the serial data port. note that the serial data can be daisy-chained from one part to another, allowing a single data line to be used to pro- gram multiple chips in the system. octal-channel ultrasound front-end with cw doppler mixers 18 ______________________________________________________________________________________ per channel msb lsb shutdown phase (degree) di + 4 di + 3 di + 2 di + 1 di 0 0 0 0 0 0/1 22.5 1 0 0 0 0/1 45 0 1 0 0 0/1 67.5 1 1 0 0 0/1 90 0 0 1 0 0/1 112.5 1 0 1 0 0/1 1 3 5 0110 0 / 1 157.5 1 1 1 0 0/1 1 8 0 0001 0 / 1 202.5 1 0 0 1 0/1 2 2 5 0101 0 / 1 247.5 1 1 0 1 0/1 2 7 0 0011 0 / 1 292.5 1 0 1 1 0/1 3 1 5 0111 0 / 1 337.5 1 1 1 1 0/1 table 3. mixer phase configurations channel 1 din dout clk ab c dsd b3 b2 b1 b0 b4 channel 2 ab c dsd b3 b2 b1 b0 b4 channel 3 ab c dsd b3 b2 b1 b0 b4 channel 4 ab c dsd b3 b2 b1 b0 b4 d43 d42 d41 d40 d44 d45 d46 channel 5 ab c dsd b3 b2 b1 b0 b4 channel 6 ab c dsd b3 b2 b1 b0 b4 channel 7 ab c dsd b3 b2 b1 b0 b4 channel 8 ab c dsd b3 b2 b1 b0 b4 figure 1. data flow of serial shift register downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 19 vga and cw mixer operation during normal operation, the max2078 is configured sothat either the vga path is enabled while the mixer array is powered down (vga mode), or the quadrature mixer array is enabled while the vga path is powered down (cw mode). for vga mode, set v/c to a logic- high and for cw mode, set v/c to a logic-low. power-down and low-power mode the max2078 can also be powered down with pd. setpd to v cc1 for power-down mode. in power-down mode, the device draws a total supply current less than1?. set pd to logic-low for normal operation. a low-power mode is available to lower the required power for cwd operation. when selected, the complex mixers operate at lower quiescent currents and the total per-channel current is lowered to 34.2ma. note that operation in this mode slightly reduces the dynamic performance of the device. table 4 shows the logic function of the standard operating modes. applications information mode select response time the mode select response time is the time that thedevice takes to switch between cw and vga modes. figure 2 depicts one possible approach to interfacing the cw outputs to an instrumentation amplifier, which is used to drive an adc. in this implementation, there are four large-value (in the range of 470nf to 1?) capaci- tors between each of the cq+, cq-, ci+, ci- outputs and the circuitry they are driving. the output of the cw mixer usually drives the input of an instrumentationamplifier made up of op amps whose input impedance is set by common-mode setting resistors. there are clearly both a highpass corner and a lowpass corner present in this output network. the lowpass cor- ner is set primarily by the 162 mixer pullup resistors, the series 50 resistors, and the shunt 0.022? capaci- tor. this lowpass corner is used to filter a combinationof lo leakage and upper sideband. the highpass cor- ner, however, is of a larger concern since it is dominat- ed by the combination of a 1? dc-blocking capacitor and the pair of shunt 31.6k resistors. pd input v/c clp vga cw mixer internal switch to vga internal switch to cw mixer 3.3v v cc current consumption 5v v cc current consumption 11v v mix current consumption 1 1 n/a off off off off 0.3? 0.4? 0 1 0 n/a off off off off 0.1? 0.6? 0 0 0 0 off on off on 3.2ma 248ma 90.4ma 0 0 1 off on off on 3.2ma 216ma 54.4ma 0 1 n/a on off on off 88ma 48ma 0 table 4. logic function of standard operating modes n/a = not applicable. 162 ci- ci+ 162 1 f 1 f 0.022 f 31.6k 31.6k 50 figure 2. typical example of a cw mixer? output circuit downloaded from: http:///
if drawn, the simplified dominant highpass networkwould look like figure 3. the highpass pole in this case is at f p = 1/(2 x pi x rc) ~ 5hz. note that this low highpass corner frequency isrequired to filter the downconverted clutter tone, which appears at dc, but not interfere with cwd imaging at frequencies as low as 400hz. for example, if one want- ed to use cwd down to 400hz, then a good choice for the highpass pole would be at least a decade below this (< 40hz) as not to incur rolloff due to the pole. remember, if the highpass pole is set to 400hz, the response is 3db down at that corner frequency. the placement of the highpass pole at 5hz in the above example is between the dc and 40hz limitations just discussed. the bottom line is that any reasonably sized dc block between the output of the mixer and the instrumentation amplifier poses a significant time constant that slows the mode select switching speed. an alternative solution to the approach in figure 2, which enables faster mode select response time, is shown in figure 4. in figure 4, the outputs of the cwd mixers are dc-cou- pled into the inputs of the instrumentation amplifiers. therefore, the op amps must be able to accommodate the full compliance range of the mixer outputs, which is a maximum of 11v when the mixers are disabled, down to the 5v supply of the max2078 when the mixers are enabled. the op amps can be powered from 11v for the high rail and 5v for the low rail, requiring a 6v op amp. serial interface the max2078 is programmed using a serial shift regis-ter arrangement. this greatly simplifies the complexity of the program circuitry, reduces the number of ic pins necessary for programming, and reduces the pcb lay- out complexity. see table 5 for the programming bit order. the data in (din) and data out (dout) can be daisy-chained from device to device and all front-ends can run off a single programming clock. the data can be entered after cs goes low. once a whole word is entered, cs needs to rise. when pro- gramming the part, enter lsb first and msb last. programming the beamformer during the normal cwd mode, the mixer clock (lo+,lo-) is on and the programming signals (din, clk, cs ) are off ( cs = high, clk = low, and din = don? care, but fixed to a high or a low). to start the programmingsequence, turn off the mixer clock. data is shifted into the shift register at a recommended 10mhz program-ming rate or 100ns minimum data clock period/time. assuming a 64-channel cwd receiver, this takes about 30ms for 5 bits per channel. see figure 5 for timing details. after the shift registers are programmed, pulling cs high loads the internal counters into i/q phase divider/selectors with the proper values. the mixer clockneeds to be off when this occurs or there may be timing issues between the load line timing and the mixer clock timing. the user turns on the mixer clock to start beam- forming. the clock must turn on so that it starts at the beginning of a mixer clock cycle. a narrow glitch on the mixer clock is not acceptable and could cause metasta- bility in the i/q phase dividers. max2078 octal-channel ultrasound front-end with cw doppler mixers 20 ______________________________________________________________________________________ figure 3. simplified circuit of highpass pole +11v +5v figure 4. improved mode select response time achieved with dc-coupled input to instrumentation amplifier downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 21 47 register bits msb lsb channel 1 (i = 1) channel 8 (i = 8) d46 d45 d44 d43 d42 d41 d40 d39 d38 d37 d36 d35 d4 d3 d2 d1 d0 d46 d45 d44 d43 d42 d41 d40 di + 4 di + 3 di + 2 di + 1 di di + 4 di + 3 di + 2 di + 1 di table 5. programming bit order din clk cs t clh t ch t cs t cw t mixcs mixer clock on mixer clock on mixer clock off mixer clock on mixer clock off mixer clock off lo+ lo- lo+ lo- mixer clock on t cws figure 5. shift register timing diagram downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 22 ______________________________________________________________________________________ ultrasound front-end cwd beamformer the user provides an lo frequency of 16mhz to120mhz. this high clock frequency requires a differential lvds input. note that the lvds cwd lo clocks are dc- coupled. this is to ensure immediate synchronization when the clock is first turned on. an ac-coupled lo is problematic in that the rc time constant associated with the coupling capacitors and the input impedance of the pin results in a period of time (related to the rc time con- stant) when the dc level on the chip side of the capaci- tor is outside the acceptable common-mode range and the lo swing cannot overcome both of the logic thresh- olds required for proper operation. this problem associ- ated with ac coupling would cause an inability to ensure synchronization among beamforming channels. the lvds signal is terminated differentially with an external 100 resistor on the board. the lo input is divided internally by 16 to produce 16 phases at a fre-quency of 1mhz to 7.5mhz. there is one divider per channel. each channel has a corresponding 5-bit shift register (4 bits for phase programming and 1 bit for channel enable) that is used to program the output phase of the divide-by-16 circuit. the first 4 bits of the shift register are for programming the 16 phases, and the fifth bit can be used to turn on/off each channel individually through the serial bus. cw mixer output summation the maximum differential current output is typically3ma p-p and the mixer output-compliance voltage ranges from 4.5v to 12v per mixer channel. the mixercommon-mode current in each of the differential mixer outputs is typically 2.83ma. the total summed current would equal n x 2.83ma in each of the 162 load resis- tors (where n = number of channels). in this case, thequiescent output voltage at +v sum and -v sum outputs would be 11v - (n x 2.83ma x 162 ) = 11v - (8 x 2.83ma x 162 ) = 7.34v. the voltage swing at each output, with one channel driven at maximum output cur-rent (differential 2.8ma p-p ) while the other channels are not driven, would be 1.4ma p-p x 162 or 226mv p-p and the differential voltage would be 452mv p-p . the voltage compliance range is defined as the valid rangefor +v sum and -v sum in this example. active impedance matching to provide exceptional noise-figure characteristics, theinput impedance of each amplifier uses a feedback topology for active impedance matching. a feedback resistor of the value (1 + (a/2)) x r s is added between the inverting input of the amplifier to the output. theinput impedance is the feedback resistor (z f ) divided by 1 + (a/2). the factor of two is due to the gain of the amplifier (a) being defined with a differential output. forcommon input impedances, the internal digitally pro- grammed impedances can be used (see tables 1 and 2). for other input impedances, program the imped- ance for external resistor operation, and then use an externally supplied resistor to set the input impedance according to the above formula. noise figure the max2078 is designed to provide maximum inputsensitivity with exceptionally low noise figure. the input active devices are selected for very-low-equivalent input noise voltage and current, optimized for source impedances from 50 to 1000 . additionally, the noise contribution of the matching resistor is effectively divid-ed by 1 + (a/2). using this scheme, typical noise figure of the amplifier is approximately 2.4db for r in = r s = 200 . table 6 illustrates the noise figure for other input impedances. input clamp the max2078 includes configurable integrated input-clamping diodes. the diodes are clamped to ground at 0.8v. the input-clamping diodes can be used to pre- vent large transmit signals from overdriving the inputs ofthe amplifiers. overdriving the inputs could possibly place charge on the input-coupling capacitor, causing longer transmit overload recovery times. input signals are ac-coupled to the single-ended inputs in1?n8, but are clamped with the inc1?nc8 inputs. see the typical application circuit . if external clamping devices are pre- ferred, simply leave inc1?nc8 unconnected. analog output coupling the differential outputs of the vga are capable of dri-ving a differential load capacitance to gnd at each of the differential outputs of 25pf, and the differential capacitance across the vga outputs is 15pf, r l = 1k . the differential outputs have a common-mode bias of approximately 1.73v. ac-couple these differen-tial outputs if the next stage has a different common- mode input range. r s ( )r in ( ) nf (db) 50 50 4.5 100 100 3.4 200 200 2.4 1000 1000 2.1 table 6. noise figure vs. source andinput impedances downloaded from: http:///
ultrasound-specific imd3 specification unlike typical communications applications, the twoinput tones are not equal in magnitude for the ultra- sound-specific imd3 two-tone specification. in this measurement, f 1 represents reflections from tissue and f 2 represents reflections from blood. the latter reflec- tions are typically 25db lower in magnitude, and hencethe measurement is defined with one input tone 25db lower than the other. the imd3 product of interest (f 1 - (f 2 - f 1 )) presents itself as an undesired doppler error signal in ultrasound applications (see figure 6). pcb layout the pin configuration of the max2078 is optimized tofacilitate a very compact physical layout of the device and its associated discrete components. a typical application for this device might incorporate several devices in close proximity to handle multiple channels of signal processing. the exposed pad (ep) of the max2078? tqfn-ep package provides a low thermal-resistance path to the die. it is important that the pcb on which the max2078 is mounted be designed to conduct heat from the ep. in addition, provide the ep with a low-inductance path to electrical ground. the ep must be soldered to a ground plane on the pcb, either directly or through anarray of plated via holes. max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 23 -25db ultrasound imd3 f 1 - (f 2 - f 1 )f 2 + (f 2 - f 1 ) f 1 f 2 figure 6. ultrasound imd3 measurement technique downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers 24 ______________________________________________________________________________________ typical application circuit 58 59 60 61 62 54 55 56 57 63 38 39 40 41 42 43 44 45 46 47 zf5 inc7 v cc1 11v ci+ci- cq+ cq- v/c np cs dinclk 52 53 v cc2 v cc2 out1+ in7 in7 in8 in8 zf8 v cc2 inc8 v cc1 v ref vg- ref vg+ vg- dout vg+clp gndgnd pd dout out3-out4+ out4- v cc1 lo+ lo+ out5- lo- lo- out5+ out6+ out6- 35 36 37 out7+ out7- out8+ *ep *ep = exposed pad. ag gnd inc4 in4 zf4 inc6 in6 zf6 inc5 in5 inc3 in3 zf3 inc2 48 out3+ in2 64 v cc2 65 66 67 inc1in1 in1 in2 zf1 68 zf2 23 22 21 20 19 27 26 25 24 18 29 28 32 31 30 v cc2 out8- out8- 34 33 49 50 out2+out2- 51 + out1- 11 10 9 8 7 6 5 4 3 2 16 15 14 13 12 1 zf7 17 max2078 in3 r4162 r3162 r2162 r1162 c39 10nf c1 22nf c2 10nf c3 22nf c38 10nf c35 100nf c36100nf c3722nf c334.7nf c12 22nf c11 10nf c34 100nf c13 10nf c14 22nf c15 100nf c16 100nf c17 100nf c404.7nf c6 1 f out1+ c31 4.7nf out2+ c32 4.7nf out1- c29 4.7nf out3+ c30 4.7nf out2- c24 4.7nf out5+ c23 4.7nf out5- c22 4.7nf out6+ c21 4.7nf out6- c20 4.7nf out7+ c18 4.7nf out8+ c19 4.7nf out7- c27 4.7nf out4+ c28 4.7nf out3- c25 100nf c26 4.7nf out4- v/cnp csb dinclk v cc1 v cc2 v cc1 in4 c4 10nf c5 22nf in5 c7 10nf c8 22nf in6 c9 10nf c10 22nf downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers ______________________________________________________________________________________ 25 chip information process: complementary bicmos package information for the latest package outline information and land patterns(footprints), go to www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only.package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 68 tqfn-ep t6800+2 21-0142 90-0099 downloaded from: http:///
max2078 octal-channel ultrasound front-end with cw doppler mixers maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. 26 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 6/09 initial release 1 10/09 corrected two minor errors 16, 24 2 9/11 updated input impedance value in ac electrical characteristics?ga mode 4 downloaded from: http:///

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