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high speed, low cost, triple op amp ada4861-3 rev. a information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 www.analog.com fax: 781.461.3113 ?2006 analog devices, inc. all rights reserved. features high speed 730 mhz, ?3 db bandwidth 625 v/s slew rate 13 ns settling time to 0.5% wide supply range: 5 v to 12 v low power: 6 ma/amplifier 0.1 db flatness: 100 mhz differential gain: 0.01% differential phase: 0.02 low voltage offset: 100 v (typical) high output current: 25 ma power down applications consumer video professional video broadband video adc buffers active filters pin configuration power down 1 1 out 2 14 power down 2 2 ?in 2 13 power down 3 3 +in 2 12 +v s 4 ?v s 11 +in 1 5 +in 3 10 ?in 1 6 ?in 3 9 out 1 7 out 3 8 ada4861-3 05708-001 figure 1. general description the ada4861-3 is a low cost, high speed, current feedback, triple op amp that provides excellent overall performance. the 730 mhz, ?3 db bandwidth, and 625 v/s slew rate make this amplifier well suited for many high speed applications. with its combination of low price, excellent differential gain (0.01%), differential phase (0.02), and 0.1 db flatness out to 100 mhz, this amplifier is ideal for both consumer and professional video applications. the ada4861-3 is designed to operate on supply voltages as low as +5 v and up to 5 v using only 6 ma/amplifier of supply current. to further reduce power consumption, each amplifier is equipped with a power-down feature that lowers the supply current to 0.3 ma/amplifier when not being used. the ada4861-3 is available in a 14-lead soic_n package and is designed to work over the extended temperature range of ?40c to +105c. 6.1 6.0 5.9 5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 0.1 1 10 100 1000 05708-011 closed-loop gain (db) frequency (mhz) g = +2 v out = 2v p-p r f = r g = 301 ? v s = +5v v s = 5v figure 2. large signal 0.1 db flatness
ada4861-3 rev. a | page 2 of 16 table of contents features .............................................................................................. 1 applications....................................................................................... 1 pin configuration............................................................................. 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications..................................................................................... 3 absolute maximum ratings............................................................ 5 thermal resistance ...................................................................... 5 esd caution.................................................................................. 5 typical performance characteristics ............................................. 6 applications..................................................................................... 13 gain configurations .................................................................. 13 20 mhz active low-pass filter ................................................ 13 rgb video driver ...................................................................... 14 driving two video loads ......................................................... 14 power-down pins ............................................................... 14 single-supply operation ........................................................... 15 power supply bypassing ............................................................ 15 layout .......................................................................................... 15 outline dimensions ....................................................................... 16 ordering guide .......................................................................... 16 revision history 3/06rev 0 to rev. a changes to 20 mhz active low-pass filter section.................. 13 changes to figure 48 and figure 49............................................. 13 10/05revision 0: initial version
ada4861-3 rev. a | page 3 of 16 specifications v s = +5 v (@ t a = 25c, g = +2, r l = 150 , c l = 4 pf, unless otherwise noted); for g = +2, r f = r g = 301 ; and for g = +1, r f = 499 . table 1. parameter conditions min typ max unit dynamic performance C3 db bandwidth v o = 0.2 v p-p 350 mhz v o = 2 v p-p 145 mhz g = +1, v o = 0.2 v p-p 560 mhz bandwidth for 0.1 db flatness v o = 2 v p-p 85 mhz +slew rate (rising edge) v o = 2 v p-p 590 v/s ?slew rate (falling edge) v o = 2 v p-p 480 v/s settling time to 0.5% (rise/fall) v o = 2 v step 12/13 ns noise/distortion performance harmonic distortion hd2/hd3 f c = 1 mhz, v o = 2 v p-p ?81/?89 dbc harmonic distortion hd2/hd3 f c = 5 mhz, v o = 2 v p-p ?69/?76 dbc input voltage noise f = 100 khz 3.8 nv/hz input current noise f = 100 khz, +in/?in 1.7/5.5 pa/hz differential gain 0.02 % differential phase 0.03 degrees all-hostile crosstalk amplifier 1 and amplifier 2 driven, amplifier 3 output measured, f = 1 mhz ?65 db dc performance input offset voltage ?13 ?0.9 +13 mv +input bias current ?2 ?0.8 +1 a ?input bias current ?8 +2.3 +13 a open-loop transresistance 400 620 k input characteristics input resistance +in 14 m ?in 85 input capacitance +in 1.5 pf input common-mode voltage range g = +1 1.2 to 3.8 v common-mode rejection ratio v cm = 2 v to 3 v ?54 ?56.5 db power-down pins input voltage enabled 0.6 v power down 1.8 v bias current enabled ?3 a power down 115 a turn-on time 200 ns turn-off time 3.5 s output characteristics output overdrive recovery time (rise/fall) v in = +2.25 v to ?0.25 v 55/100 ns output voltage swing r l = 150 1.2 to 3.8 1.1 to 3.9 v r l = 1 k 0.9 to 4.1 0.85 to 4.15 v short-circuit current sinking and sourcing 65 ma power supply operating range 5 12 v total quiescent current enabled 12.5 16.1 18.5 ma quiescent current/amplifier power down pins = +v s 0.2 0.33 ma power supply rejection ratio +psr +v s = 4 v to 6 v, ?v s = 0 v ?60 ?64 db
ada4861-3 rev. a | page 4 of 16 v s = 5 v (@ t a = 25c, g = +2, r l = 150 , c l = 4 pf, unless otherwise noted); for g = +2, r f = r g = 301 ; and for g = +1, r f = 499 . table 2. parameter conditions min typ max unit dynamic performance C3 db bandwidth v o = 0.2 v p-p 370 mhz v o = 2 v p-p 210 mhz g = +1, v o = 0.2 v p-p 730 mhz bandwidth for 0.1 db flatness v o = 2 v p-p 100 mhz +slew rate (rising edge) v o = 2 v p-p 910 v/s ?slew rate (falling edge) v o = 2 v p-p 680 v/s settling time to 0.5% (rise/fall) v o = 2 v step 12/13 ns noise/distortion performance harmonic distortion hd2/hd3 f c = 1 mhz, v o = 2 v p-p ?85/?99 dbc harmonic distortion hd2/hd3 f c = 5 mhz, v o = 2 v p-p ?73/?86 dbc input voltage noise f = 100 khz 3.8 nv/hz input current noise f = 100 khz, +in/?in 1.7/5.5 pa/hz differential gain 0.01 % differential phase 0.02 degrees all-hostile crosstalk amplifier 1 and amplifier 2 driven, amplifier 3 output measured, f = 1 mhz ?65 db dc performance input offset voltage ?13 ?0.1 +13 mv +input bias current ?2 ?0.7 +1 a ?input bias current ?8 +2.9 +13 a open-loop transresistance 500 720 k input characteristics input resistance +in 15 m ?in 90 input capacitance +in 1.5 pf input common-mode voltage range g = +1 ?3.7 to +3.7 v common-mode rejection ratio v cm = 2 v ?55 ?58 db power-down pins input voltage enabled ?4.4 v power down ?3.2 v bias current enabled ?3 a power down 250 a turn-on time 200 ns turn-off time 3.5 s output characteristics output overdrive recovery time (rise/fall) v in = 3.0 v 30/90 ns output voltage swing r l = 150 2 ?3.1 to +3.65 v r l = 1 k 3.9 4.05 v short-circuit current sinking and sourcing 100 ma power supply operating range 5 12 v total quiescent current enabled 13.5 17.9 20.5 ma quiescent current/amplifier power down pins = +v s 0.3 0.5 ma power supply rejection ratio +psr +v s = 4 v to 6 v, ?v s = ?5 v ?63 ?66 db ?psr +v s = 5 v, ?v s = ?4 v to ?6 v, power down pins = ?v s ?59 ?62 db
ada4861-3 rev. a | page 5 of 16 absolute maximum ratings table 3. parameter rating the power dissipated in the package (p d ) is the sum of the quiescent power dissipation and the power dissipated in the die due to the amplifiers drive at the output. the quiescent power is the voltage between the supply pins (v s ) times the quiescent current (i s ). supply voltage 12.6 v power dissipation see figure 3 common-mode input voltage ?v s + 1 v to +v s ? 1 v differential input voltage v s p d = quiescent power + ( total drive power ? load power ) storage temperature ?65c to +125c () l out l out s ss d r v r vv ivp 2 C 2 ? ? ? ? ? ? += operating temperature range ?40c to +105c lead temperature jedec j-std-20 junction temperature 150c rms output voltages should be considered. stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. airflow increases heat dissipation, effectively reducing ja . in addition, more metal directly in contact with the package leads and through holes under the device reduces ja . figure 3 shows the maximum safe power dissipation in the package vs. the ambient temperature for the 14-lead soic_n (90c/w) on a jedec standard 4-layer board. ja values are approximations. thermal resistance ja is specified for the worst-case conditions, that is, ja is specified for device soldered in circuit board for surface-mount packages. 2.5 0 ambient temperature ( c) maximum power dissipation (w) 05708-002 ?55 125 ?45?35?25?15?5 5 152535455565758595105115 2.0 1.5 1.0 0.5 table 4. thermal resistance package type ja unit 14-lead soic_n 90 c/w maximum power dissipation the maximum safe power dissipation for the ada4861-3 is limited by the associated rise in junction temperature (t j ) on the die. at approximately 150 c, which is the glass transition temperature, the plastic changes its properties. even temporarily exceeding this temperature limit can change the stresses that the package exerts on the die, permanently shifting the parametric performance of the amplifiers. exceeding a junction temperature of 150c for an extended period can result in changes in silicon devices, potentially causing degradation or loss of functionality. figure 3. maximum power dissipation vs. temperature for a 4-layer board esd caution esd (electrostatic discharge) sensitive device. electros tatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge wi thout detection. although this product features proprietary esd protection circuitry, permanent dama ge may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality.
ada4861-3 rev. a | page 6 of 16 typical performance characteristics r l = 150 and c l = 4 pf, unless otherwise noted. 1 ?6 ?5 ?4 ?3 ?2 ?1 0 0.1 1 10 100 1000 05708-038 normalized gain (db) frequency (mhz) g = +1, r f = 499 ? g = +2, r f = r g = 301 ? g = ?1, r f = r g = 301 ? g = +5, r f = 200 ? , r g = 49.9 ? g = +10, r f = 200 ? , r g = 22.1 ? v s = 5v v out = 0.2v p-p 1 ?6 ?5 ?4 ?3 ?2 ?1 0 0.1 1 10 100 1000 05708-037 normalized gain (db) frequency (mhz) v s = 5v v out = 0.2v p-p g = +1, r f = 499 ? g = +2, r f = r g = 301 ? g = ?1, r f = r g = 301 ? g = +5, r f = 200 ? , r g = 49.9 ? g = +10, r f = 200 ? , r g = 22.1 ? figure 4. small signal frequency response for various gains figure 7. small signal frequency response for various gains 1 ?6 ?5 ?4 ?3 ?2 ?1 0 0.1 1 10 100 1000 05708-028 normalized gain (db) frequency (mhz) g = ?1, r f = r g = 301 ? g = +5, r f = 200 ? , r g = 49.9 ? g = +2, r f = r g = 301 ? g = +1, r f = 499 ? g = +10, r f = 200 ? , r g = 22.1 ? v s = 5v v out = 2v p-p 1 ?6 ?5 ?4 ?3 ?2 ?1 0 0.1 1 10 100 1000 05708-027 normalized gain (db) frequency (mhz) g = ?1, r f = r g = 301 ? g = +5, r f = 200 ? , r g = 49.9 ? g = +2, r f = r g = 301 ? g = +1, r f = 499 ? g = +10, r f = 200 ? , r g = 22.1 ? v s = 5v v out = 2v p-p figure 8. large signal frequency response for various gains figure 5. large signal frequency response for various gains 7 0 1 2 3 4 5 6 0.1 1 10 100 1000 05708-029 closed-loop gain (db) frequency (mhz) v s = 5v g = +2 v out = 1v p-p v out = 2v p-p v out = 4v p-p 6.1 6.0 5.9 5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 0.1 1 10 100 1000 05708-011 closed-loop gain (db) frequency (mhz) g = +2 v out = 2v p-p r f = r g = 301 ? v s = +5v v s = 5v figure 6. large signal 0.1 db flatness figure 9. large signal frequency response for various output levels
ada4861-3 rev. a | page 7 of 16 7 6 5 4 3 2 1 0 0.1 1 10 100 1000 05708-012 closed-loop gain (db) frequency (mhz) v s = 5v g = +2 r g = r f v out = 0.2v p-p r f = 499 ? r f = 301 ? r f = 402 ? r f = 604 ? 7 6 5 4 3 2 1 0 0.1 1 10 100 1000 05708-013 closed-loop gain (db) frequency (mhz) v s = 5v g = +2 r f = r g v out = 2v p-p r f = 499 ? r f = 301 ? r f = 402 ? r f = 604 ? figure 13. large signal frequency response vs. r f figure 10. small signal frequency response vs. r f distortion (dbc) 05708-049 ? 40 15 ? 0 frequency (mhz) 10 ?50 ?60 ?70 ?80 ?90 ?100 v s = 5v g = +1 v out = 2v p-p hd3 v out = 3v p-p hd3 v out = 3v p-p hd2 v out = 2v p-p hd2 figure 11. harmonic distortion vs. frequency distortion (dbc) 05708-048 ? 40 ?110 15 0 frequency (mhz) 10 ?50 ?60 ?70 ?80 ?90 ?100 v out =2vp-p hd3 v s =5v g=+1 v out =2vp-p hd2 v out =1vp-p hd3 v out =1vp-p hd2 figure 12. harmonic distortion vs. frequency distortion (dbc) 05708-051 40 15 0 frequency (mhz) 10 ?50 ?60 ?70 ?80 ?90 ?100 v s =5v g=+2 v out =3vp-p hd3 v out =2vp-p hd3 v out =3vp-p hd2 v out =2vp-p hd2 figure 14. harmonic distortion vs. frequency ? distortion (dbc) 05708-050 40 ?110 15 0 frequency (mhz) 10 ?50 ?60 ?70 ?80 ?90 ?100 v s =5v g=+2 v out =2vp-p hd3 v out =1vp-p hd2 v out =1vp-p hd3 v out =2vp-p hd2 figure 15. harmonic distortion vs. frequency
ada4861-3 rev. a | page 8 of 16 output voltage (v) +v s = 5v, ?v s = 0v 200 100 0 ?100 ?200 2.7 2.6 2.5 2.4 2.3 output voltage (mv) v s = 5v g = +1 v out = 0.2v p-p time = 5ns/div 05708-015 v s = +5v v s = 5v output voltage (v) +v s = 5v, ?v s = 0v 200 100 0 ?100 ?200 2.7 2.6 2.5 2.4 2.3 output voltage (mv) v s = 5v g = +2 v out = 0.2v p-p time = 5ns/div v s = +5v v s = 5v 05708-014 figure 16. small signal transient response for various supplies figure 19. small signal transient response for various supplies 200 100 0 ?100 ?200 output voltage (mv) 05708-040 v s = 5v g = +1 v out = 0.2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf 200 100 0 ?100 ?200 output voltage (mv) 05708-042 v s = 5v g = +2 v out = 0.2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf figure 17. small signal transient response for various capacitor loads figure 20. small signal transient response for various capacitor loads 2.7 2.6 2.5 2.4 2.3 output voltage (v) 05708-039 v s = 5v g = +1 v out = 0.2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf 2.7 2.6 2.5 2.4 2.3 output voltage (v) 05708-041 v s = 5v g = +2 v out = 0.2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf figure 21. small signal transient response for various capacitor loads figure 18. small signal transient response for various capacitor loads
ada4861-3 rev. a | page 9 of 16 output voltage (v) +v s = 5v, ?v s = 0v 1.5 0.5 0 ?1.0 1.0 ?0.5 ?1.5 4.0 3.0 2.5 1.5 3.5 2.0 1.0 output voltage (v) v s = 5v g = +1 v out = 2v p-p time = 5ns/div v s = 5v 05708-017 v s = +5v output voltage (v) +v s = 5v, ?v s = 0v 1.5 0.5 0 ?1.0 1.0 ?0.5 ?1.5 4.0 3.0 2.5 1.5 3.5 2.0 1.0 output voltage (v) v s = 5v g = +2 v out = 2v p-p time = 5ns/div v s = 5v 05708-016 v s = +5v figure 22. large signal transient response for various supplies figure 25. large signal transient response for various supplies 1.5 ?1.5 ?1.0 ?0.5 0 0.5 1.0 output voltage (v) 05708-031 v s = 5v g = +1 v out = 2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf 1.5 ?1.0 ?0.5 0 0.5 1.0 output voltage (v) 05708-033 v s = 5v g = +2 v out = 2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf ?1.5 figure 26. large signal transient response for various capacitor loads figure 23. large signal transient response for various capacitor loads 4.0 1.0 1.5 2.0 2.5 3.0 3.5 output voltage (v) 05708-032 v s = 5v g = +2 v out = 2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf 4.0 1.0 1.5 2.0 2.5 3.0 3.5 output voltage (v) 05708-030 v s = 5v g = +1 v out = 2v p-p time = 5ns/div c l = 9pf c l = 4pf c l = 6pf figure 27. large signal transient response for various capacitor loads figure 24. large signal transient response for various capacitor loads
ada4861-3 rev. a | page 10 of 16 4.54.03.53.0 2.52.01.51.00.5 05708-036 slew rate (v/s) input voltage (v p-p) 1800 1600 1400 1200 1000 800 600 400 200 0 05 . 0 1400 0 200 400 600 800 1000 1200 02 . 2 5 2.001.75 1.501.251.000.75 0.50 0.25 2.50 05708-018 slew rate (v/s) input voltage (v p-p) v s = 5v g = +1 v s = 5v g = +2 positive slew rate negative slew rate positive slew rate negative slew rate figure 28. slew rate vs. input voltage figure 31. slew rate vs. input voltage 700 0 100 200 300 400 500 600 02 2.0 1.5 1.0 0.5 3.0 05708-021 slew rate (v/s) input voltage (v p-p) v s = 5v g = +1 . 5 positive slew rate negative slew rate 700 0 100 200 300 400 500 600 01 1.00 0.75 0.50 0.25 1.50 05708-019 slew rate (v/s) input voltage (v p-p) v s = 5v g = +2 . 2 5 positive slew rate negative slew rate figure 29. slew rate vs. input voltage figure 32. slew rate vs. input voltage 1.00 t = 0s ?1.00 ?0.75 ?0.50 ?0.25 0 0.25 0.50 0.75 05708-022 settling time (%) v s = 5v g = +2 v out = 2v p-p time = 5ns/div v in 1v 1.00 t = 0s 1v ?1.00 ?0.75 ?0.50 ?0.25 0 0.25 0.50 0.75 05708-020 settling time (%) v s = 5v g = +2 v out = 2v p-p time = 5ns/div v in figure 30. settling time rising edge figure 33. settling time falling edge
ada4861-3 rev. a | page 11 of 16 0 ?10 ?20 ?40 ?30 ?50 ?60 ?70 ?80 ?90 ?100 0.1 1 10 100 1000 05708-024 crosstalk (db) frequency (mhz) v s = 5v, +5v g = +2 v out = 2v p-p 1000 0.1 1 10 100 ?180 ?135 ?90 ?45 0 0.01 0.1 1 10 100 1000 05708-044 transimpedance (k ? ) phase (degrees) frequency (mhz) v s = 5v g = +2 transimpedance phase figure 37. large signal all-hostile crosstalk figure 34. transimpedance and phase vs. frequency 0 ?70 ?60 ?50 ?40 ?30 ?20 ?10 0.01 0.1 1 10 100 1000 05708-045 common-mode rejection (db) frequency (mhz) v s = 5v g = +2 v in = 2v p-p 0 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ?10 0.01 0.1 1 10 100 1000 05708-023 power supply rejection (db) frequency (mhz) v s = 5v g = +2 ?psr +psr figure 38. common-mode rejection vs. frequency figure 35. power supply re jection vs. frequency 6 ?6 ?5 ?4 ?3 ?2 ?1 0 1 2 3 4 5 0 1000 900800 700600500400300200100 05708-035 output and input voltage (v) time (ns) input voltage 2 output voltage v s = 5v g = +2 f = 1mhz 5.5 ?0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 1000 900800 700600500400300200100 05708-034 output and input voltage (v) time (ns) input voltage 2 output voltage v s = 5v g = +2 f = 1mhz figure 36. output overdrive recovery figure 39. output overdrive recovery
ada4861-3 rev. a | page 12 of 16 35 0 5 10 15 20 25 30 10 100 1k 10k 100k 05708-052 input voltage noise (nv/ hz) frequency (hz) v s = 5v, +5v 60 0 10 20 30 40 50 10 100 1k 10k 100k 05708-053 input current noise (pa/ hz) frequency (hz) v s = 5v, +5v noninverting input inverting input figure 40. input voltage noise vs. frequency figure 43. input current noise vs. frequency 19 18 17 16 15 total supply current (ma) 05708-043 14 4 5 6 7 8 9 10 11 12 supply voltage (v) 20 19 18 17 16 15 14 13 12 ?40 125110958065503520 5 ?10?25 05708-025 total supply current (ma) temperature (c) v s = 5v v s = +5v figure 41. total supply cu rrent vs. supply voltage figure 44. total supply current at various supplies vs. temperature 25 ?25 ?20 ?15 ?10 ?5 0 5 10 15 20 ?5?4?3?2?1012345 05708-046 input v os (mv) v cm (v) v s = 5v v s = +5v 20 ?15 ?10 ?5 0 5 10 15 ?5?4?3?2?1012345 05708-026 input bias current ( a) output voltage (v) v s = 5v v s = +5v figure 42. input v os vs. common-mode voltage figure 45. input bias current vs. output voltage
ada4861-3 rev. a | page 13 of 16 applications gain configurations 20 mhz active low-pass filter unlike conventional voltage feedback amplifiers, the feedback resistor has a direct impact on the closed-loop bandwidth and stability of the current feedback op amp circuit. reducing the resistance below the recommended value can make the amplifier response peak and even become unstable. increasing the size of the feedback resistor reduces the closed-loop bandwidth. the ada4861-3 triple amplifier lends itself to higher order active filters. figure 48 shows a 28 mhz, 6-pole, sallen-key low-pass filter. v in u1 op amp out + ? r1 562 ? r2 562 ? c2 10pf c1 10pf r12 301? r11 210k ? u2 op amp out + ? r3 562 ? r4 562 ? c4 10pf c3 10pf r10 301? r9 210 ? 05708-007 u3 op amp out + ? r5 562 ? r6 562 ? c6 10pf c5 10pf r8 301 ? r7 210 ? v out table 5 provides a convenient reference for quickly determining the feedback and gain set resistor values and bandwidth for common gain configurations. table 5. recommended values and frequency performance 1 large signal 0.1 db flatness gain r f () r g () ?3 db ss bw (mhz) +1 499 n/a 730 90 ?1 301 301 350 60 +2 301 301 370 100 +5 200 49.9 180 30 +10 200 22.1 80 15 1 conditions: v s = 5 v, t a = 25c, r l = 150 . figure 46 and figure 47 show the typical noninverting and inverting configurations and recommended bypass capacitor values. 0 5708-005 0.1f 10f ?v s v in r g v out 10f 0.1f + v s ada4861-3 + ? r f figure 48. 28 mhz, 6-pole low-pass filter the filter has a gain of approximately 23 db and flat frequency response out to 22 mhz. this type of filter is commonly used at the output of a video dac as a reconstruction filter. the frequency response of the filter is shown in figure 49 . figure 46. noninverting gain 30 20 ?70 ?60 ?50 ?40 ?30 ?20 ?10 0 10 1 10 100 200 05708-047 magnitude (db) frequency (mhz) 0 5708-006 0.1f 10f ?v s v in v out 10f 0.1f +v s ada4861-3 + ? r f r g figure 47. inverting gain figure 49. 20 mhz low-pass filter frequency response
ada4861-3 rev. a | page 14 of 16 05708-004 75 ? cable 75 ? cable 75? 75? 75? v out 2 v out 1 ?v s +v s v in 0.1f 0.1f 10f 10f 75 ? cable 75? 75? + ? r f 301? r g 301 ? ada4861-3 rgb video driver figure 50 shows a typical rgb driver application using bipolar supplies. the gain of the amplifier is set at +2, where r f = r g = 301 . the amplifier inputs are terminated with shunt 75 resistors, and the outputs have series 75 resistors for proper video matching. in figure 50 , the power-down pins are not shown connected to any signal source for simplicity. if the power-down function is not used, it is recommended that the power-down pins be tied to the negative supply and not be left floating (not connected). for applications that require a fixed gain of +2, consider using the figure 51. video driver schematic for two video loads ada4862-3 with integrated r f and r g. the ada4862-3 is another high performance triple current feedback amplifier that can simplify design and reduce board area. 0.1 ?0.9 ?0.8 ?0.7 ?0.6 ?0.5 ?0.4 ?0.3 ?0.2 ?0.1 0 1 10 100 400 05708-010 normalized gain (db) frequency (mhz) v s = 5v r l = 75 ? v out = 2v p-p r f 301 ? r g 301? 75 ? 75? v out (r) v in (r) 7 5 6 r f 301 ? r g 301? 75 ? 75? v out (g) v in (g) 8 10 9 r f 301 ? r g 301? 75 ? 75? v out (b) v in (b) 14 12 13 1 2 3 10f 0.1f + v s 4 0.1f 10f ?v s 11 pd1 pd2 pd3 05708-003 figure 52. large signal frequency response for various supplies, r l = 75 power-down pins the ada4861-3 is equipped with three independent power down pins, one for each amplifier. this allows the user the ability to reduce the quiescent supply current when an amplifier is inactive. the power-down threshold levels are derived from the voltage applied to the ?v s pin. when used in single-supply applications, this is especially useful with conventional logic levels . the amplifier is powered down when the voltage applied to the power down pins is greater than ?v s + 1 v. in a single-supply application, this is > +1 v (that is, 0 v + 1 v), in a 5 v supply application, the voltage is > ?4 v. the amplifier is enabled whenever the power down pins are left either open or the voltage on the power down pins is lower than 1 v above ?v s . if the power down pins are not used, it is best to connect them to the negative supply. figure 50. rgb video driver driving two video loads in applications that require two video loads be driven simultaneously, the ada4861-3 can deliver. figure 51 shows the ada4861-3 configured with dual video loads. figure 52 shows the dual video load 0.1 db bandwidth performance.
ada4861-3 rev. a | page 15 of 16 single-supply operation power supply bypassing the ada4861-3 can also be operated from a single power supply. careful attention must be paid to bypassing the power supply pins of the ada4861-3. high quality capacitors with low equivalent series resistance (esr), such as multilayer ceramic capacitors (mlccs), should be used to minimize supply voltage ripple and power dissipation. a large, usually tantalum, 2.2 f to 47 f capacitor located in proximity to the ada4861-3 is required to provide good decoupling for lower frequency signals. the actual value is determined by the circuit transient and frequency requirements. in addition, 0.1 f mlcc decoupling capacitors should be located as close to each of the power supply pins as is physically possible, no more than 1/8 inch away. the ground returns should terminate immediately into the ground plane. locating the bypass capacitor return close to the load return minimizes ground loops and improves performance. figure 53 shows the schematic for a single 5 v supply video driver. the input signal is ac-coupled into the amplifier via c1. resistor r2 and resistor r4 establish the input midsupply reference for the amplifier. capacitor c5 prevents constant current from being drawn through the gain set resistor and enables the ada4861-3 at dc to provide unity gain to the input midsupply voltage, thereby establishing the output voltage dc operating point. capacitor c6 is the output coupling capacitor. for more information on single-supply operation of op amps, see www.analog.com/library/analogdialogue/archives/35- 02/avoiding/ . 0 5708-054 c2 1f r2 50k? r4 50k ? r3 1k? c1 22f r1 50? c6 220f r5 75? r6 75? c5 22f ada4861-3 +5v v out v in ?v s c3 2.2f c4 0.01f +5 v layout as is the case with all high-speed applications, careful attention to printed circuit board (pcb) layout details prevents associated board parasitics from becoming problematic. the ada4861-3 can operate at up to 730 mhz; therefore, proper rf design techniques must be employed. the pcb should have a ground plane covering all unused portions of the component side of the board to provide a low impedance return path. removing the ground plane on all layers from the area near and under the input and output pins reduces stray capacitance. signal lines connecting the feedback and gain resistors should be kept as short as possible to minimize the inductance and stray capacitance associated with these traces. termination resistors and loads should be located as close as possible to their respective inputs and outputs. input and output traces should be kept as far apart as possible to minimize coupling (crosstalk) through the board. adherence to microstrip or stripline design techniques for long signal traces (greater than 1 inch) is recommended. for more information on high speed board layout, go to: figure 53. single-supply video driver schematic www.analog.com and www.analog.com/library/analogdialogue/archives/39- 09/layout.htm l.
ada4861-3 rev. a | page 16 of 16 outline dimensions controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design. compliant to jedec standards ms-012-ab coplanarity 0.10 14 8 7 1 6.20 (0.2441) 5.80 (0.2283) 4.00 (0.1575) 3.80 (0.1496) 8.75 (0.3445) 8.55 (0.3366) 1.27 (0.0500) bsc seating plane 0.25 (0.0098) 0.10 (0.0039) 0.51 (0.0201) 0.31 (0.0122) 1.75 (0.0689) 1.35 (0.0531) 8 0 0.50 (0.0197) 0.25 (0.0098) 1.27 (0.0500) 0.40 (0.0157) 0.25 (0.0098) 0.17 (0.0067) 45 figure 54. 14-lead standard small outline package [soic_n] narrow body (r-14) dimensions shown in millimeters and (inches) ordering guide model temperature range package descript ion package option ordering quantity ada4861-3yrz C40c to +105c 14-lead soic_n r-14 1 1 ADA4861-3YRZ-RL C40c to +105c 14-lead soic_n r-14 2,500 1 14-lead soic_n ADA4861-3YRZ-RL7 C40c to +105c r-14 1,000 1 1 z = pb-free part. ?2006 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d05708-0-3/06(a)

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