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Quad, 235 MHz, DC-Coupled VGA and Differential Output Amplifier AD8264
FEATURES
Low noise Voltage noise: 2.3 nV/Hz Current noise: 2 pA/Hz Wide bandwidth Small signal: 235 MHz (VGAx); 80 MHz (differential output amplifier) Large signal: 80 MHz (1 V p-p) Gain range 0 to 24 dB (input to VGA output) 6 to 30 dB (input to differential output) Gain scaling: 20 dB/V DC-coupled Single-ended input and differential output Supplies: 2.5 V to 5 V Low power: 140 mW per channel @ 3.3 V
OPP1
IPP1 IPN1 GNH1
FUNCTIONAL BLOCK DIAGRAM
COMM VPOS VNEG VGA1 + PrA 6dB - ATTENUATOR -24dB TO 0dB 18dB + 6dB - VOL1 VOH1 OFS1 VGA2 18dB + 6dB - VOL2 VOH2 OFS2 VGA3 + PrA 6dB - ATTENUATOR -24dB TO 0dB + CH3 GAIN - CONTROL 18dB + 6dB - VOL3 VOH3 OFS3 VGA4 + PrA 6dB - ATTENUATOR -24dB TO 0dB + - 18dB + 6dB - VOL4 VOH4 OFS4
07736-001
OPP2 IPP2 IPN2 GNH2 OPP3 IPP3 IPN3 GNH3 + PrA 6dB -
+ CH1 GAIN CONTROL -
ATTENUATOR -24dB TO 0dB + CH2 GAIN - CONTROL
APPLICATIONS
Multichannel data acquisition Positron emission tomography Gain trim Industrial and medical ultrasound Radar receivers
OPP4 IPP4 IPN4 GNH4
CH4 GAIN CONTROL
GNLO
VOCM
Figure 1.
GENERAL DESCRIPTION
The AD8264 is a 4-channel, linear-in-dB, general-purpose variable gain amplifier (VGA) with a preamplifier (preamp), and a flexible differential output buffer. Intended for a broad range of applications, dc coupling combined with wide bandwidth makes this amplifier a very good pulse processor. Each channel includes a single-ended input preamp/VGA section to preserve the wide bandwidth and fast slew rate for lowdistortion pulse applications. A 6 dB differential output buffer with common-mode and offset adjustments enable direct coupling to most modern high speed analog-to-digital converters (ADCs), using the converter reference output for perfect dc matching levels. The -3 dB bandwidth of the preamp/VGA is dc to 235 MHz, and the bandwidth of the differential driver is 80 MHz. The floating gain control interface provides a precise linear-in-dB scale of 20 dB/V and is easy to interface to a variety of external circuits. The gain of each channel is adjusted independently, and all channels are referenced to a single pin, GNLO. Combined with a multi-output, digital-to-analog converter (DAC), each section of the AD8264 can be used for active calibration or as a trim amplifier. The gain range of the VGA section is 24 dB. Operation from a dual polarity power supply enables amplification of negative voltage pulses that are generated by current-sinking pulses into a grounded load, such as is typical of photodiodes or photomultiplier tubes (PMT). Delay-free processing of wide-band video signals is also possible. The differential output amplifier permits convenient level shifting and interfacing to singlesupply ADCs using the VOCM and OFSx pins. The AD8264 is available in a 40-lead, 6 mm x 6 mm LFCSP with an operating temperature range of -40C to +105C.
Rev. 0
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 (c)2009 Analog Devices, Inc. All rights reserved.
AD8264 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 6 Thermal Resistance ...................................................................... 6 Maximum Power Dissipation ..................................................... 6 ESD Caution .................................................................................. 6 Pin Configuration and Function Descriptions ............................. 7 Typical Performance Characteristics ............................................. 8 Test Circuits ..................................................................................... 20 Theory of Operation ...................................................................... 28 Overview ..................................................................................... 28 Preamp ......................................................................................... 28 VGA ............................................................................................. 28 Post Amplifier ............................................................................. 29 Noise ............................................................................................ 29 Applications Information .............................................................. 30 A Low Channel Count Application Concept Using a Discrete Reference ..................................................................................... 30 A DC Connected Concept Example ........................................ 31 Evaluation Board ............................................................................ 34 Connecting and Using the AD8264-EVALZ .......................... 34 Outline Dimensions ....................................................................... 38 Ordering Guide .......................................................................... 38
REVISION HISTORY
5/09--Revision 0: Initial Version
Rev. 0 | Page 2 of 40
AD8264 SPECIFICATIONS
VS = 2.5 V, TA = 25C, f = 10 MHz, CL = 5 pF, RL = 500 per output (VGAx, VOHx, VOLx), VGAIN = (VGNHx - VGNLO) = 0 V, VVOCM = GND, VOFSx = GND, gain range = 6 dB to 30 dB, unless otherwise specified. Table 1.
Parameter GENERAL PERFORMANCE -3 dB Small Signal Bandwidth (VGAx) -3 dB Large Signal Bandwidth (VGAx) -3 dB Small Signal Bandwidth (Differential Output)1 -3 dB Large Signal Bandwidth (Differential Output)1 Slew Rate Conditions VOUT = 10 mV p-p VOUT = 1 V p-p VOUT = 100 mV p-p VOUT = 2 V p-p VGAx, VOUT = 2 V p-p VGAx, VOUT = 1 V p-p Differential output, VOUT = 2 V p-p Differential output, VOUT = 1 V p-p Pins IPPx Pins IPPx at dc; VIN/IBIAS Pins IPPx Pins IPPx at 10 MHz Min Typ 235 150 80 80 380 290 470 220 -5 4.2 2 7.9 2.3 2 9 72 45 3.5 <1 |VS| - 1.3 |VS| - 1.3 |VS| - 0.5 |<1| |<5| |<10| Max Unit MHz MHz MHz MHz V/s V/s V/s V/s A M pF k nV/Hz pA/Hz dB nV/Hz nV/Hz V V V mV mV mV
Input Bias Current Input Resistance Input Capacitance Input Impedance Input Voltage Noise Input Current Noise Noise Figure (Differential Output) Output-Referred Noise (Differential Output) Output Impedance Output Signal Range
-8
-3
Output Offset Voltage
VGAIN = 0.7 V, RS = 50 , unterminated VGAIN = 0.7 V (Gain = 30 dB) VGAIN = -0.7 V (Gain = 6 dB) VGAx, dc to 10 MHz Differential output, dc to 10 MHz Preamp VGAx, RL 500 Differential amplifier, RL 500 per side Preamp offset VGAx offset, VGAIN = 0.7 V Differential output offset, VGAIN = 0.7 V VGAx = 1 V p-p, differential output = 2 V p-p (measured at VGAx) f = 1 MHz f = 10 MHz f = 35 MHz VGAx = 1 V p-p, differential output = 2 V p-p (measured at differential output) f = 1 MHz f = 10 MHz f = 35 MHz VGAIN = -0.7 V, f = 10 MHz VGAIN = +0.7 V, f = 10 MHz
-6 -18 -38
+6 +18 +38
DYNAMIC PERFORMANCE Harmonic Distortion HD2 HD3 HD2 HD3 HD2 HD3
-73 -68 -71 -61 -60 -53
dBc dBc dBc dBc dBc dBc
HD2 HD3 HD2 HD3 HD2 HD3 Input 1 dB Compression Point
-78 -66 -71 -43 -56 -20 7 -9.6
dBc dBc dBc dBc dBc dBc dBm 2 dBm
Rev. 0 | Page 3 of 40
AD8264
Parameter Two-Tone Intermodulation Distortion (IMD3) Conditions VGAx = 1 V p-p, f1 = 10 MHz, f2 = 11 MHz VGAx = 1 V p-p, f1 = 35 MHz, f2 = 36 MHz VOUT = 2 V p-p, f1 = 10 MHz, f2 = 11 MHz VOUT = 2 V p-p, f1 = 35 MHz, f2 = 36 MHz VGAx = 1 V p-p, f = 10 MHz VGAx = 1 V p-p, f = 35 MHz VOUT = 2 V p-p, f = 10 MHz VOUT = 2 V p-p, f = 35 MHz Overload Recovery Group Delay Variation ACCURACY Absolute Gain Error 3 VGAIN = 0.7 V, VIN stepped from 0.1 V p-p to 1 V p-p 1 MHz < f < 100 MHz, full gain range -0.7 V < VGAIN < -0.6 V -0.6 V < VGAIN < -0.5 V -0.5 V < VGAIN < +0.5 V 0.5 V < VGAIN < 0.6 V 0.6 V < VGAIN < 0.7 V -0.5 V < VGAIN < +0.5 V, 2.5 V VS 5 V -0.5 V < VGAIN < +0.5 V, -40C TA +105C Single IC, -0.5 V < VGAIN < +0.5 V, -40C TA +105C Multiple ICs, -0.5 V < VGAIN < +0.5 V, -40C TA +105C -0.5 V < VGAIN < +0.5 V -40C TA +105C 0 -1.25 -1 -1.25 -3 Min Typ -68 -51 -49 -34 32 19 23 10 30 17 21 8 25 1 0.2 to 2 0.35 0.25 0.35 -0.2 to -2 0.2 0.3 0.1 to 0.25 0.25 dB 19.5 20.0 20 0.5 24 11.9 11.9 0.4 17.9 17.9 0.4 70 -0.4 -0.4 +0.2 -1.2 -1.2 +0.4 200 1.5 1.5 0.3 6 6 0.5 20.5 dB/V dB/V dB dB dB dB dB V M A A A A ns nA nA V dB dB 3 +1.25 +1 +1.25 0 Max Unit dBc dBc dBc dBc dBm dBVRMS dBm dBVRMS dBm dBVRMS dBm dBVRMS ns ns dB dB dB dB dB dB dB dB
Output Third-Order Intercept
Gain Law Conformance 4 Channel-to-Channel Matching
-0.5
+0.5
GAIN CONTROL INTERFACE Gain Scaling Factor Over Temperature Gain Range Gain Intercept to VGAx Over Temperature Gain Intercept to Differential Output Over Temperature GNHx Input Voltage Range Input Resistance GNHx Input Bias Current Over Temperature GNLO Input Bias Current Over Temperature Response Time OUTPUT BUFFER VOCM Input Bias Current Over Temperature VOCM Input Voltage Range Gain (VGAx to Differential Output) Over Temperature
11.5 -40C TA +105C 17.5 -40C TA +105C GNLO = 0 V, no gain foldover VIN/IBIAS, -0.7 V < VGAIN < +0.7 V -0.7 V < VGAIN < 0.7 V -0.7 V < VGAIN < 0.7 V, -40C TA +105C -0.7 V < VGAIN < 0.7 V -0.7 V < VGAIN < 0.7 V, -40C TA +105C 24 dB gain change -VS -0.9
12.2 18.2 +VS 0
0.3 -40C TA +105C OFSx = 0 V, VGAx = 0 V -40C TA +105C -1.4 5.75
2.5 +1.4 6.25
Rev. 0 | Page 4 of 40
AD8264
Parameter POWER SUPPLY Supply Voltage Power Consumption Quiescent Current Conditions Min 2.5 Typ Max 5 Unit V
Power Dissipation
PSRR
VS = 2.5 V VS = 2.5 V, -40C TA +105C VS = 3.3 V VS = 3.3 V, -40C TA +105C VS = 5 V VS = 5 V, -40C TA +85C 5 VS = 2.5 V VS = 3.3 V VS = 5 V From VPOS to differential output, VGAIN = 0.7 V From VNEG to differential output, VGAIN = 0.7 V
65 70 81
79 79 25 85 85 30 99 99 30 395 560 990 -15 -15
88 95 110
mA mA mA mA mA mA mW mW mW dB dB
1 2
Differential Output = (VOHx - VOLx). All dBm values are calculated with 50 reference, unless otherwise noted. 3 Conformance to theoretical gain expression (see Equation 1 in the Theory of Operation section). 4 Conformance to best-fit dB linear curve. 5 For supplies greater than 3.3 V, the operating temperature range is limited to -40C TA +85C.
Rev. 0 | Page 5 of 40
AD8264 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Voltage Supply Voltage (VPOS, VNEG) Input Voltage (INPx) Gain Voltage (GNHx, GNLO) Power Dissipation Temperature Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering, 60 sec) Package Glass Transition Temperature (TG) Rating 6 V VPOS, VNEG VPOS, VNEG 2.5 W -40C to +105C -65C to +150C 300C 150C
THERMAL RESISTANCE
JA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. The JA values in Table 3 assume a 4-layer JEDEC standard board with zero airflow. Table 3. Thermal Resistance
Package Type 40-Lead LFCSP1
1
JA 31.0
JC 2.3
Unit C/W
4-Layer JEDEC board (2S2P).
MAXIMUM POWER DISSIPATION
The maximum safe power dissipation for the AD8264 is limited by the associated rise in junction temperature (TJ) on the die. At approximately 150C, which is the glass transition temperature, the properties of the plastic change. Even temporarily exceeding this temperature limit may change the stresses that the package exerts on the die, permanently shifting the parametric performance of the amplifiers. Exceeding a temperature of 150C for an extended period can cause changes in silicon devices, potentially resulting in a loss of functionality.
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.
ESD CAUTION
Rev. 0 | Page 6 of 40
AD8264 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
IPP1 COMM GNH1 GNH2 GNLO VPOS VNEG OFS1 OFS2 VGA1
40 39 38 37 36 35 34 33 32 31 IPN1 OPP1 OPP2 IPN2 IPP2 IPP3 IPN3 OPP3 OPP4 IPN4 1 2 3 4 5 6 7 8 9 10
PIN1 INDICATOR
AD8264
TOP VIEW (Not to Scale)
30 29 28 27 26 25 24 23 22 21
VOL1 VOH1 VOH2 VOL2 VGA2 VGA3 VOL3 VOH3 VOH4 VOL4
11 12 13 14 15 16 17 18 19 20
VOCM VPOS VNEG OFS4 OFS3 IPP4 COMM GNH4 GNH3 VGA4
Figure 2. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. 0 (EP), 12, 39 1, 4, 7, 10 2, 3, 8, 9 5, 6, 11, 40 13, 14, 37, 38 15 16, 35 17, 34 18, 19, 32, 33 20, 25, 26, 31 21, 24, 27, 30 22, 23, 28, 29 36 Mnemonic COMM IPN1, IPN2, IPN3, IPN4 OPP1, OPP2, OPP3, OPP4 IPP1, IPP2, IPP3, IPP4 GNH1, GNH2, GNH3, GNH4 VOCM VPOS VNEG OFS1, OFS2, OFS3, OFS4 VGA4, VGA3 VGA2, VGA1 VOL1, VOL2 VOL3, VOL4 VOH1, VOH2, VOH3, VOH4 GNLO Description Ground. Exposed paddle (EP, Pin 0) needs an electrical connection to ground. For proper RF grounding and increased reliability, the pad must be connected to the ground plane. Negative Preamp Inputs for Channel 1 Through Channel 4. Normally, no external connection is needed. Preamp Output for Channel 1 Through Channel 4. This pin is internally connected to the attenuator (VGA) input, and normally, no external connection is needed. Positive Preamp Input for Channel 1 Through Channel 4. High impedance. Positive Gain Control Voltage Input for Channel 1 Through Channel 4. This pin is referenced to GNLO (Pin 36). This pin sets the differential output amplifier (VOHx and VOLx) common-mode voltage. Positive Supply (Internally Tied Together). Negative Supply (Internally Tied Together). Voltage sets the differential output offset for Channel 1 through Channel 4. This is the noninverting input to the differential amplifier, and it has the same bandwidth as the inverting input (VGAx). VGA Output for Channel 1 Through Channel 4. Negative Differential Amplifier Output for Channel 1 Through Channel 4. Positive Differential Amplifier Output for Channel 1 Through Channel 4. Negative Gain Control Input (Reference for GNHx Pins).
Rev. 0 | Page 7 of 40
07736-003
NOTES 1. EXPOSED PADDLE (PIN 0) NEEDS AN ELECTRICAL CONNECTION TO GROUND. FOR PROPER RF GROUNDING AND INCREASED RELIABILITY, THE PAD MUST BE CONNECTED TO THE GROUND PLANE.
AD8264 TYPICAL PERFORMANCE CHARACTERISTICS
VS = 2.5 V, TA = 25C, f = 10 MHz, CL = 5 pF, RL = 500 per output (VGAx, VOHx, VOLx), VGAIN = (VGNHx - VGNLO) = 0 V, VVOCM = GND, VOFSx = GND, gain range = 6 dB to 30 dB, unless otherwise specified.
36 30 24
GAIN (dB)
-40C -40C +25C +25C +85C +85C +105C +105C
140 120
DIFFERENTIAL OUTPUT
VGAIN = 0V
MEAN: -0.1dB SD: 0.05dB
100 80
12 6 0 -6 -0.7
VGA
HITS
18
60 40 20 0 -0.6
07736-004
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
-0.4
-0.2
0
0.2
0.4
VGAIN (V)
GAIN ERROR (dB)
Figure 3. Gain vs. VGAIN vs. Temperature
2.0 1.5 1.0 TA = +105C TA = +25C TA = -40C MAX MIN
Figure 6. VGA Absolute Gain Error Histogram
180 150 120
MEAN: 20.1dB SD: 0.09dB
GAIN ERROR (dB)
0.5 0 -0.5
HITS
90 60
-1.0 -1.5 -2.0 -0.7
30 0 19.0
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
07736-005
19.5
20.0 GAIN SCALING (dB/V)
20.5
21.0
VGAIN (V)
Figure 4. Gain Error vs. VGAIN vs. Temperature
2
Figure 7. Gain Scale Factor Histogram (-0.4 V < VGAIN < +0.4 V)
1
1MHz 10MHz 70MHz 100MHz 150MHz
MEAN: 11.9dB SD: 0.08dB 80
GAIN ERROR (dB)
0
HITS
60
-1
40
-2
20
-3
0 11.7
-0.5
-0.3
-0.1 0.1 VGAIN (V)
0.3
0.5
0.7
07736-006
11.8
11.9
12.0
12.1
GAIN INTERCEPT (dB)
Figure 5. Gain Error vs. VGAIN at Various Frequencies to VGAx
Figure 8. VGA Gain Intercept Histogram
Rev. 0 | Page 8 of 40
07736-009
-4 -0.7
07736-008
07736-007
AD8264
700 600 500 400 CH 1 TO CH 2 CH 1 TO CH 3 CH 1 TO CH 4
30
VGAIN = 0V
VOUT = 0.1V p-p
20 10
GAIN (dB)
0 -10 -20 -30 -40 100k CL = 0pF CL = 10pF CL = 22pF 1M 10M FREQUENCY (Hz) 100M 500M
07736-012 07736-014
07736-013
HITS
300 200 100 0 -0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
GAIN ERROR MATCHING (dB)
Figure 9. Channel-to-Channel Gain Match Histogram
30 24 18 12 GAIN (dB)
GAIN (dB)
07736-028
Figure 12. Frequency Response to Differential Output for Various Capacitive Loads
30 VOUT = 0.1V p-p 20 10 0 -10 -20 -30 -40 100k
PIN = -28dBm
6 0 -6 -12 -18 100k
VGAIN = +0.7V VGAIN = +0.5V VGAIN = +0.2V VGAIN = 0V VGAIN = -0.2V VGAIN = -0.5V VGAIN = -0.7V 1M 10M FREQUENCY (Hz) 100M
07736-010
CL = 0pF CL = 10pF CL = 22pF 1M 10M FREQUENCY (Hz) 100M
Figure 10. Frequency Response vs. Gain to VGAx for Various Values of VGAIN
40 30 20 10
GAIN (dB)
Figure 13. Frequency Response to Differential Output for Various Capacitive Loads with Series R = 10
20
VOUT = 0.1V p-p
PIN = -44dBm
10
0 -10 -20 -30 -40 100k
GAIN (dB)
VGAIN = +0.7V VGAIN = +0.5V VGAIN = +0.2V VGAIN = 0V VGAIN = -0.2V VGAIN = -0.5V VGAIN = -0.7V 1M 10M
FREQUENCY (Hz)
0
-10
-20
100M
07736-011
-30 100k
CL = 0pF CL = 10pF CL = 22pF CL = 47pF 1M 10M 100M 500M
FREQUENCY (Hz)
Figure 11. Frequency Response vs. Gain to Differential Output for Various Values of VGAIN
Figure 14. Small Signal Frequency Response to VGAx for Various Capacitive Loads
Rev. 0 | Page 9 of 40
AD8264
20 PIN = -10dBm
24 30 VOUT = 0.1V p-p VGAIN = +0.7V
10
18 VGAIN = 0V
GAIN (dB)
GAIN (dB)
0
12 6 0 -6
-10
VGAIN = -0.7V
-20
1M
10M FREQUENCY (Hz)
100M
500M
07736-015
1M
10M FREQUENCY (Hz)
100M
500M
Figure 15. Large Signal Frequency Response to VGAx for Various Capacitive Loads
20 PIN = -28dBm
Figure 18. Small Signal Frequency Response vs. Gain to VGAx for Various Supply Voltages
40 30 VOUT = 0.1V p-p
VGAIN = +0.7V VGAIN = 0V VGAIN = -0.7V
10
20
GAIN (dB)
GAIN (dB)
0
10 0 -10 -20
-10
-20
07736-016
1M
10M FREQUENCY (Hz)
100M
500M
1M
10M FREQUENCY (Hz)
100M
500M
Figure 16. Small Signal Frequency Response to VGAx for Various Capacitive Loads with Series R = 10
20 PIN = -8dBm 10
Figure 19. Small Signal Frequency Response vs. Gain to Differential Output for Various Supply Voltages
36 30 24
VOUT = 0.1V p-p VGAIN = 0.7V
DIFFERENTIAL OUTPUT VGA
GAIN (dB)
GAIN (dB)
0
18 12 6
-10
-20
1M
10M FREQUENCY (Hz)
100M
500M
FREQUENCY (Hz)
Figure 17. Large Signal Frequency Response to VGAx for Various Capacitive Loads with Series R = 10
Figure 20. Large Signal Frequency Response to VGAx and Differential Output for Various Supply Voltages
Rev. 0 | Page 10 of 40
07736-020
1M
10M
100M
500M
07736-017
-30 100k
CL = 47pF CL = 22pF CL = 10pF CL = 0pF
0 -6 100k
VS = 5V VS = 3.3V VS = 2.5V VS = 5V VS = 3.3V VS = 2.5V
07736-019
-30 100k
CL = 47pF CL = 22pF CL = 10pF CL = 0pF
-30 -40 100k
VS = 5V VS = 3.3V VS = 2.5V
07736-018
-30 100k
CL = 47pF CL = 22pF CL = 9pF CL = 0pF
-12 -18 100k
VS = 5V VS = 3.3V VS = 2.5V
AD8264
1
5
PIN = -16dBm
4
0
DELAY (ns)
GAIN (dB)
3 VGAIN = -0.7V 2 VGAIN = +0.7V VGAIN = 0V
-1
-2
07736-021
1M
10M
FREQUENCY (Hz)
100M
10M FREQUENCY (Hz)
100M
Figure 21. Frequency Response from VOCM to VOHx and VOLx for Various Supplies
9 VOUT = 0.1V p-p 3
Figure 24. Group Delay vs. Frequency to VGAx
8
7
VGAIN = -0.7V
6
DELAY (ns)
GAIN (dB)
-3
5
VGAIN = +0.7V
VGAIN = 0V
-9
4
-15 VS = 5V VS = 3.3V VS = 2.5V 1M 10M FREQUENCY (Hz) 100M 500M
07736-022
3
FREQUENCY (Hz)
Figure 22. Frequency Response from OFSx to Differential Output for Various Supply Voltages
12 PIN = -22dBm
10 15
Figure 25. Group Delay vs. Frequency to Differential Output
TA = +105C TA = +25C TA = -40C MAX MIN
6
OFFSET VOLTAGE RTO (mV)
GAIN (dB)
5
0
0
-6 VS = 2.5V VS = 3.3V VS = 5V
07736-023
-5
1M
10M FREQUENCY (Hz)
100M
1G
VGAIN (V)
Figure 23. Preamp Frequency Response to OPPx
Figure 26. Differential Output Offset Voltage vs. VGAIN vs. Temperature
Rev. 0 | Page 11 of 40
07736-026
-12 100k
-10 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
07736-025
-21 100k
2 1M
10M
100M
07736-024
-3 100k
VS = 2.5V, VOHx VS = 3.3V, VOHx VS = 5V, VOHx VS = 2.5V, VOLx VS = 3.3V, VOLx VS = 5V, VOLx
1
0 1M
AD8264
10 TA = +105C TA = +25C TA = -40C MAX MIN
100
OFFSET VOLTAGE RTO (mV)
OUTPUT RESISTANCE ()
5
10
VS = 2.5V
0
1
VS = 5V
-5
VGAIN (V)
07736-027
1
10 FREQUENCY (MHz)
100
Figure 27. VGAx Output Offset Voltage vs. VGAIN vs. Temperature
3000
Figure 30. Output Resistance (VOHx, VOLx) vs.Frequency
10
2500
VGAIN = -0.4V VGAIN = 0V VGAIN = +0.4V
OUTPUT RESISTANCE ()
2000
HITS
VS = 5V VS = 2.5V
1500
1000
500
1
10
FREQUENCY (MHz)
100
OUTPUT OFFSET VOLTAGE (mV)
Figure 28. Output Offset Histogram to VGAx
800 700 600 500
HITS
100
Figure 31. Output Resistance (VGAx) vs. Frequency
VGAIN = -0.4V VGAIN = 0V VGAIN = +0.4V
OUTPUT NOISE (nV/Hz)
80
60 DIFFERENTIAL OUTPUT 40
400 300 200 100 0 -30
20 VGAx 0 -0.7
OUTPUT OFFSET VOLTAGE (mV)
VGAIN (V)
Figure 29. Output Offset Histogram to Differential Output
Figure 32. Output Referred Noise to VGAx and Differential Output vs. VGAIN
Rev. 0 | Page 12 of 40
07736-032
-20
-10
0
10
20
30
07736-095
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
07736-031
-20
-10
0
10
20
30
07736-029
0 -30
1 0.1
07736-030
-10 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
0.1 0.1
AD8264
100
35
INPUT REFERRED NOISE (nV/Hz)
30
DIFFERENTIAL OUTPUT (TERMINATED)
NOISE FIGURE (dB)
25 VGAx (TERMINATED) 20 VGAx (UNTERMINATED) DIFFERENTIAL OUTPUT (UNTERMINATED)
DIFFERENTIAL OUTPUT 10
15
VGAx
10
VGAIN (V)
VGAIN (V)
Figure 33. Input Referred Noise from VGAx and Differential Output vs. VGAIN
100
Figure 36. Noise Figure vs. VGAIN
-10
INPUT REFERRED NOISE (nV/Hz)
-20
-30 CMRR (dB)
10
-40
-50
DIFFERENTIAL OUTPUT VGAx
07736-034
-60
1
10 FREQUENCY (MHz)
100
FREQUENCY (Hz)
Figure 34. Input Referred Noise vs. Frequency at Maximum Gain
100
Figure 37. VOCM Common-Mode Rejection Ratio vs. Frequency
-30
INPUT REFERRED NOISE (nV/Hz)
-40
HD2, HD3, HD2, HD3,
VS = 2.5V VS = 2.5V VS = 5V VS = 5V
-50
10
HD (dBc)
-60
-70 DIFFERENTIAL OUTPUT VGAx
07736-035
-80
1
RSOURCE ()
RLOAD ()
Figure 35. Input Referred Noise vs. RSOURCE
Figure 38. Harmonic Distortion to VGAx vs. RLOAD and Various Supplies
Rev. 0 | Page 13 of 40
07736-038
1
10
100
1k
10k
-90
0
400
800
1200
1600
2000
07736-037
1
1
100
1k
10k
100k
1M
10M
100M
-70 0.1
07736-036
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
07736-033
1 -0.7
5 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
AD8264
-30 HD2, HD3, HD2, HD3, VS = 2.5V VS = 2.5V VS = 5V VS = 5V -30
-40
-40
-50
-50
-60
HD2 (dBc)
HD (dBc)
-60
-70
-70
-80
-80
-90
07736-039
CLOAD (pF)
VGAIN (V)
Figure 39. Harmonic Distortion to VGAx vs. CLOAD
-30 -20 -30 -40 -50
Figure 42. HD2 vs. VGAIN vs. Frequency to VGAx
-40
HD2, HD3, HD2, HD3,
VS = 2.5V VS = 2.5V VS = 5V VS = 5V
HD3 (dBc)
HD (dBc)
-50 -60 -70 -80 -90 -0.7 1MHz 10MHz 35MHz 100MHz
07736-043 07736-044
-60
-70
-80
-90
07736-040
0
400
800
1200
1600
2000
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
RLOAD ()
VGAIN (V)
Figure 40. Harmonic Distortion to Differential Output vs. RLOAD and Various Supplies
-30 HD2, VS = 2.5V HD3, VS = 2.5V -40 -40 -30
Figure 43. HD3 vs. VGAIN vs. Frequency to VGAx
VGAx = 0.5Vp-p VGAx = 1Vp-p VGAx = 2Vp-p
-50
-50
HD2 (dBc)
HD (dBc)
INPUT LIMITED -60
-60
-70
-70
-80
-80
-90
07736-041
0
10
20
30
40
50
-90 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
CLOAD (pF)
VGAIN (V)
Figure 41. Harmonic Distortion to Differential Output vs. CLOAD
Figure 44. HD2 vs. Amplitude to VGAx
Rev. 0 | Page 14 of 40
07736-042
0
10
20
30
40
50
-90 -0.7
1MHz 10MHz 35MHz 100MHz -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7
AD8264
-30 VGAx = 0.5V p-p VGAx = 1V p-p VGAx = 2V p-p INPUT LIMITED
-30
-40
-40
VOUT = 0.5V p-p VOUT = 1V p-p VOUT = 2V p-p
-50
-50
HD2 (dBc) -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7
HD3 (dBc)
-60
-60
-70
-70
-80
-80
07736-045
VGAIN (V)
VGAIN (V)
Figure 45. HD3 vs. Amplitude to VGAx
-30
Figure 48. HD2 vs. Amplitude to Differential Output
-30
-40
1MHz 10MHz 35MHz
-40
-50
-50
HD2 (dBc)
-60
HD3 (dBc)
-60
-70
-70
-80
-80
07736-046
VGAIN (V)
VGAIN (V)
Figure 46. HD2 vs. VGAIN vs. Frequency to Differential Output
0
Figure 49. HD3 vs. Amplitude to Differential Output
0 VOUT = 1V p-p -20
-15
1MHz 10MHz 35MHz
-30 IMD3 (dBc)
HD3 (dBc)
-40
-45
-60
-60
-75
-80 LOW TONE, f - 50kHz HIGH TONE, f + 50kHz
07736-047
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
10M FREQUENCY (Hz)
100M
VGAIN (V)
Figure 47. HD3 vs. VGAIN vs. Frequency to Differential Output
Figure 50. IMD3 vs. Frequency to VGAx
Rev. 0 | Page 15 of 40
07736-050
-90 -0.7
-100 1M
07736-049
-90 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
-90 -0.7
VOUT = 0.5V p-p VOUT = 1V p-p VOUT = 2V p-p -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7
07736-048
-90 -0.7
-90 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
AD8264
50 f = 1MHz, OIP3L f = 1MHz, OIP3H f = 10MHz, OIP3L f = 10MHz, OIP3H f = 35MHz, OIP3L f = 35MHz, OIP3H f = 100MHz, OIP3L f = 100MHz, OIP3H
INPUT-REFERRED P1dB (dBm)
20 15 10 5 0 -5 -10
VGAx (VS = 5V) DIFF OUT (VS = 5V) VGAx (VS = 3.3V) DIFF OUT (VS = 3.3V) VGAx (VS = 2.5V) DIFF OUT (VS = 2.5V)
07736-054
07736-056 07736-055
40
OIP3 (dBm)
30
20
10
07736-051
0 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
-15 -0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
VGAIN (V)
VGAIN (V)
Figure 51. OIP3 vs. VGAIN vs. Frequency to VGAx
0
0.10
Figure 54. Input P1dB vs. VGAIN
VOUT = 1V p-p
VGAIN = 0.7V
-20
0.05
IMD3 (dBc)
-40
VOLTAGE (V)
0
-60 LOW TONE, f - 50kHz
-0.05
-80 HIGH TONE, f + 50kHz
07736-052
-100 1M
10M FREQUENCY (Hz)
100M
-0.10 -40
-20
0
20
40
60
80
100
TIME (ns)
Figure 52. IMD3 vs. Frequency to Differential Output
50
0.15
Figure 55. Small Signal Pulse Response to VGAx
VGAIN = 0.7V
40
0.10
0.05
OIP3 (dBm)
30
VOLTAGE (V) f = 1MHz, OIP3L f = 1MHz, OIP3H f = 10MHz, OIP3L f = 10MHz, OIP3H f = 35MHz, OIP3L f = 35MHz, OIP3H -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7
07736-053
0
20
-0.05
10
-0.10
0 -0.7
-0.15 -40
-20
0
20
40
60
80
100
VGAIN (V)
TIME (ns)
Figure 53. OIP3 vs. Frequency to Differential Output
Figure 56. Small Signal Pulse Response to Differential Output
Rev. 0 | Page 16 of 40
AD8264
1.5 VGAIN = 0.7V 1.0
1.5
1.0
0.5
0.5
VOLTAGE (V)
VOLTAGE (V)
0 1V p-p
0 1V p-p -0.5 2V p-p
-0.5
-1.0
2V p-p
-1.0
-20
0
20
40
60
80
100
TIME (ns)
TIME (ns)
Figure 57. Large Signal Pulse Response to VGAx
1.5 VGAIN = 0.7V 1.0
Figure 60. OFSx Large Signal Pulse Response
1.0 VGAIN = 0.7V CL = 0pF CL = 10pF CL = 22pF
0.5
0.5
VOLTAGE (V)
0 1V p-p
VOLTAGE (V)
0
-0.5
-1.0
2V p-p
-0.5
-20
0
20
40
60
80
100
TIME (ns)
TIME (ns)
Figure 58. Large Signal Pulse Response to Differential Output
1.5
Figure 61. Large Signal Pulse Response to VGAx for Various Capacitive Loads
2.0 1.5 1.0 CL = 0pF CL = 10pF CL = 22pF
1.0
2V p-p (VOL) 2V p-p (VOH) 1V p-p (VOL) 1V p-p (VOH)
0.5
VOLTAGE (V)
0
VOLTAGE (V)
0.5 0 -0.5 -1.0
-0.5
-1.0
-1.5
-20
0
20
40
60
80
100
TIME (ns)
TIME (ns)
Figure 59. VOCM Large Signal Pulse Response
Figure 62. Large Signal Pulse Response to Differential Output for Various Capacitive Loads
Rev. 0 | Page 17 of 40
07736-062
0
20
40
60
80
100
120
140
160
07736-059
-1.5
-2.0 -40
07736-061
-20
0
20
40
60
80
100
07736-058
-1.5 -40
-1.0 -40
07736-060
-20
0
20
40
60
80
100
07736-057
-1.5 -40
-1.5 -40
AD8264
-2.0 -1.5 -1.0 VGAIN = 0.7V CL = 0pF CL = 10pF CL = 22pF 1.5
1.0
0 -0.5 -1.0 -1.5
07736-096
VOTLAGE (V)
-20 0 20 40 60 80 100
VOLTAGE (V)
-0.5
0.5
0
-0.5
-1.0
0
200
400
600 TIME (ns)
800
1000
1200
TIME (ns)
Figure 63. Large Signal Pulse Response to Differential Output for Various Capacitive Loads with Series R = 10
1.5 1.5
Figure 66. Preamp Overdrive Recovery
1.0 VGAIN PULSE 0.5
1.0
0.5 GAIN RESPONSE
VOTLAGE (V)
0
VOTLAGE (V)
0
-0.5
-0.5
-1.0
-1.0
0
200
400
600 TIME (ns)
800
1000
1200
TIME (ns)
Figure 64. VGAx Response to Change in VGAIN
1.5 0
Figure 67. VGA Overdrive Recovery
1.0
-10
VGAx (VGAIN = +0.7V) DIFF OUT (VGAIN = +0.7V) VGAx (VGAIN = -0.7V) DIFF OUT (VGAIN = -0.7V)
0.5
-20
VOTLAGE (V)
PSRR (dB)
GAIN RESPONSE 0
-30
-0.5
VGAIN PULSE
-40
-1.0
-50
0
400
800
1200
1600
2000
07736-065
1M FREQUENCY (Hz)
10M
100M
TIME (ns)
Figure 65. Differential Output Response to Change in VGAIN
Figure 68. Power Supply Rejection vs. Frequency (VPOS)
Rev. 0 | Page 18 of 40
07736-068
-1.5
-60 100k
07736-067
0
400
800
1200
1600
2000
07736-064
-1.5
-1.5
07736-066
-2.0 -40
-1.5
AD8264
5 VGAx (VGAIN = +0.7V) DIFF OUT (VGAIN = +0.7V) VGAx (VGAIN = -0.7V) DIFF OUT (VGAIN = -0.7V) 135 125 115 105 95 85 75 65 -55 100k 55 -40
-5
5V
-15
-25
SUPPLY CURRENT (mA)
PSRR (dB)
3.3V
2.5V
-35
-45
-15
10
35
60
85
110
FREQUENCY (Hz)
TEMPERATURE (C)
Figure 69. Power Supply Rejection vs. Frequency (VNEG)
Figure 70. Quiescent Supply Current vs. Temperature
Rev. 0 | Page 19 of 40
07736-070
1M
10M
100M
07736-069
AD8264 TEST CIRCUITS
VS = 2.5 V, TA = 25C, f = 10 MHz, CL = 5 pF, RL = 500 per output (VGAx, VOHx, VOLx), VGAIN = (VGNHx - VGNLO) = 0 V, VVOCM = GND, VOFSx = GND, gain range = 6 dB to 30 dB, unless otherwise specified.
DC METER
AD8264
+ - PrA 6dB
VGAx
500
IPPx 50 IPNx
+ 6dB -
VOLx
500 DC METER
VOHx
500
GNHx VGAIN
GNLO
VOCM
OFSx
07736-119
OVEN
Figure 71. Gain vs. VGAIN vs. Temperature (See Figure 3 and Figure 4)
OSCILLOSCOPE SIGNAL GENERATOR CH1 50 50 CH2
NETWORK ANALYZER
OUT 50
CH1 50 50
CH2
DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
AD8264
VGAx IPPx 50 IPNx - +
500
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOLx
500
PrA 6dB
+ 6dB -
VOLx
VOHx
VOHx
500
GNHx
VGAIN
GNLO
VOCM
OFSx
07736-100
GNHx
VGAIN
GNLO
VOCM
OFSx
07736-101
Figure 72. Gain Error vs. VGAIN at Various Frequencies to VGAx (See Figure 5)
NETWORK ANALYZER
Figure 74. Frequency Response vs. Gain to Differential Output for Various Values of VGAIN (See Figure 11)
CH1 50 50
CH2
NETWORK ANALYZER
DIFFERENTIAL PROBE
CH1 50 50
CH2
AD8264
VGAx IPPx
DIFFERENTIAL PROBE
+ -
500
50 IPNx
PrA 6dB
+ 6dB -
VOLx
IPPx + - 50 IPNx PrA 6dB
AD8264
VGAx + 6dB - VOLx 500 VOHx CL 500 CL
VOHx
GNHx VGAIN
GNLO
VOCM
OFSx
07736-072
GNHx
GNLO
VOCM
OFSx
Figure 73. Frequency Response vs. Gain to VGAx for Various Values of VGAIN, VGAIN = GNHx - GNLO (See Figure 10)
Figure 75. Frequency Response to Differential Output for Various Capacitive Loads (See Figure 12)
Rev. 0 | Page 20 of 40
07736-102
AD8264
NETWORK ANALYZER
NETWORK ANALYZER
CH1 50 50
CH2
CH1 50 50
CH2
DIFFERENTIAL PROBE
AD8264
DIFFERENTIAL PROBE
VGAx IPPx
AD8264 VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VOLx 10 500 CL 10 500 CL
+ -
50 IPNx
PrA 6dB
+ 6dB -
VOLx
VOHx
GNHx
07736-103
GNLO
VOCM
OFSx
VS VSUPPLY
07736-078
GNHx
GNLO
VOCM
OFSx
VGAIN
Figure 76. Frequency Response to Differential Output for Various Capacitive Loads with Series R = 10 (See Figure 13)
NETWORK ANALYZER
Figure 79. Frequency Response vs. Gain to VGAx for Various Supply Voltages (See Figure 18)
NETWORK ANALYZER
CH1 50 50
CH2
CH1 50 50
CH2
DIFFERENTIAL PROBE
AD8264
VGAx IPPx 50 IPNx
DIFFERENTIAL PROBE
500 CL
AD8264
VGAx IPPx 50 IPNx + - PrA 6dB + 6dB - VOLx
500
+ -
PrA 6dB
+ 6dB -
VOLx
VOHx
VOHx
500
GNHx VGAIN
GNLO
VOCM
OFSx
07736-076
GNHx
VGAIN
GNLO
VOCM
OFSx
VS VSUPPLY
07736-104
Figure 77. Frequency Response to VGAx for Various Capacitive Loads (See Figure 14)
NETWORK ANALYZER
Figure 80. Frequency Response vs. Gain to Differential Output for Various Supply Voltages (See Figure 19)
NETWORK ANALYZER
CH1 50 50
CH2
CH1 50
DIFFERENTIAL PROBE
CH2 50
AD8264
VGAx IPPx
10 500 CL
DIFFERENTIAL PROBE
AD8264
VGAx IPPx IPNx + - PrA 6dB + 6dB - VOLx 500 VOHx 500
07736-077
+ -
50 IPNx
PrA 6dB
+ 6dB -
VOLx
VOHx
GNHx VGAIN
GNLO
VOCM
OFSx
GNHx
GNLO
VOCM 50
OFSx
VS
07736-105
VSUPPLY
Figure 78. Frequency Response to VGAx for Various Capacitive Loads with Series R =10 (See Figure 16)
Figure 81. VOCM Frequency Response to Differential Output (See Figure 21)
Rev. 0 | Page 21 of 40
AD8264
NETWORK ANALYZER
CH1 50 50
CH2 DIFFERENTIAL PROBE
SPECTRUM ANALYZER CH1 CH2 50 50
AD8264
VGAx IPPx IPNx + - PrA 6dB + 6dB - VOLx
AD8264
VGAx IPPx IPNx
AD8129
10x
500
VOHx
+ -
PrA 6dB
+ 6dB -
VOLx
500
GNHx GNLO VOCM OFSx 50 VS
07736-106
VOHx
AD8129
10x
VGAIN
Figure 82. OFSx Frequency Response to Differential Output (See Figure 22)
Figure 85. Output Referred Noise vs. VGAIN (See Figure 32)
SPECTRUM ANALYZER CH1 CH2 220 50
AD8264
IPPx IPNx + - PrA 6dB
VGAx
500
50
50
+ 6dB -
VOLx
500 DC METER
AD8264
VGAx IPPx IPNx + - PrA 6dB + 6dB - VOHx VOLx
AD8129
10x
VOHx
500
GNHx
GNLO
VOCM
OFSx OVEN
AD8129
10x
VGAIN
07736-110
Figure 83. Output Offset Voltage vs. VGAIN vs. Temperature (See Figure 26 and Figure 27)
NETWORK ANALYZER CH1 CH2 50 50
Figure 86. Input Referred Noise vs. Frequency (See Figure 34)
NOISE METER
NOISE SOURCE
50
AD8264
VGAx
AD8264
VGAx IPPx
IPPx 50 IPNx
+ -
PrA 6dB
+ 6dB -
VOLx
+ -
50 IPNx
PrA 6dB
+ 6dB -
VOLx
VOHx
VOHx
GNHx
VGAIN
GNLO
VOCM
OFSx
07736-115
GNHx
GNLO
VOCM
OFSx
VS
VSUPPLY
07736-111
Figure 84. Output Resistance vs. Frequency (See Figure 30 and Figure 31)
Figure 87. Noise Figure vs. VGAIN (See Figure 36)
Rev. 0 | Page 22 of 40
07736-113
GNHx
GNLO
VOCM
OFSx
07736-112
VSUPPLY
GNHx
GNLO
VOCM
OFSx
AD8264
SPECTRUM ANALYZER CH1 CH2 50 50 50 220
AD8264
VGAx IPPx RS IPNx + - PrA 6dB + 6dB - VOHx VOLx
50 0.1F AD8129 10x
50 0.1F 50 0.1F 1k
AD8129
10x
Figure 88. Input Referred Noise vs. RSOURCE (See Figure 35)
NETWORK ANALYZER
SPECTRUM ANALYZER OUT SIGNAL GENERATOR 50
07736-114
GNHx
GNLO
VOCM
OFSx
1k
CH1
CH1 50 50
CH2
50
DIFFERENTIAL PROBE
LPF
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOLx 500 VOHx 500
07736-116
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VOLx
10 CL
GNHx
GNLO
VOCM
OFSx
Figure 89. VOCM Common-Mode Rejection vs. Frequency (See Figure 37)
SPECTRUM ANALYZER OUT 50 SIGNAL GENERATOR 50
OUT
Figure 91. Harmonic Distortion to VGAx vs. CLOAD (Figure 39)
CH1
SIGNAL GENERATOR SPECTRUM ANALYZER
500 LPF
50 50
CH1
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VOLx
IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VS RL
VSUPPLY
LPF
450
AD8264
VGAx VOLx
AD8130
1x
GNHx
GNLO
VOCM
OFSx
VS
07736-117
GNHx
GNLO
VOCM
OFSx
RL
07736-128
VSUPPLY
Figure 90. Test Circuit Harmonic Distortion to VGAx vs. RLOAD and Various Supplies (See Figure 38)
Figure 92. Harmonic Distortion to Differential Output vs. RLOAD and Various Supplies (See Figure 40)
Rev. 0 | Page 23 of 40
07736-118
GNHx
GNLO
VOCM
OFSx
AD8264
OUT SIGNAL GENERATOR SPECTRUM ANALYZER
OUT 50
SIGNAL GENERATOR
SPECTRUM ANALYZER
CH1 50
50 50
CH1
LPF
450
LPF
350
AD8264
VGAx IPPx + -
AD8264
VGAx IPPx + - PrA 6dB VOLx 6dB - VOHx
VS
07736-131
50 IPNx
PrA 6dB
+ 6dB -
VOLx
50
10
+
AD8130
1x
IPNx
AD8130
1x
VOHx
10 CL
07736-129
GNHx
GNLO
VOCM
OFSx
CL
GNHx
VGAIN
GNLO
VOCM
OFSx
Figure 93. Harmonic Distortion to Differential Output vs. CLOAD (See Figure 41)
SIGNAL GENERATOR SPECTRUM ANALYZER
Figure 95. HD2 and HD3 to Differential Output (See Figure 46 through Figure 49)
SPECTRUM ANALYZER
OUT 50
CH1 50 450
OUT SIGNAL GENERATOR 50 50
CH1
450 50 IPPx + - 50 IPNx PrA 6dB
LPF
AD8264
VGAx + 6dB - VOHx VOLx
AD8264
VGAx IPPx + - PrA 6dB VOLx 6dB
SIGNAL GENERATOR
OUT
50 IPNx
+ -
50 GNHx
VGAIN
GNHx
VGAIN
GNLO
VOCM
OFSx
07736-130
Figure 94. HD2 and HD3 to VGAx (See Figure 42 Through Figure 45)
Figure 96. IMD3 and OIP3 to VGAx (See Figure 50 and Figure 51)
SPECTRUM ANALYZER
CH1 50
OUT SIGNAL GENERATOR 50
450 50 IPPx + - 50 IPNx PrA 6dB
AD8264
VGAx 10 + 6dB - VOHx VOLx 10
SIGNAL GENERATOR 50
OUT
AD8130
1x
GNHx
GNLO
VOCM
OFSx
Figure 97. IMD3 and OIP3 to Differential Output (See Figure 52 and Figure 53)
Rev. 0 | Page 24 of 40
07736-133
500
500
07736-132
VOHx
GNLO
VOCM
OFSx
AD8264
NETWORK ANALYZER CH2 CH1 50 50 50
500
OSCILLOSCOPE
CH3
CH1 50 DIFFERENTIAL PROBE
AD8264
DIFFERENTIAL PROBE
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOLx 500 VOHx 500 GNHx PULSE GENERATOR OUT 50
07736-120
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOLx 500 VOHx
GNLO
VOCM
OFSx
50
500 GNHx
VGAIN
GNLO
VOCM
OFSx
07736-134
Figure 98. Input P1dB vs. VGAIN (See Figure 54)
OSCILLOSCOPE PULSE GENERATOR CH1 50 50 CH2
Figure 101. VOCM Pulse Response (See Figure 59)
OSCILLOSCOPE
OUT 50
CH1 50 DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
AD8264
VGAx IPPx + - PrA 6dB VOLx 6dB - VOHx
AD8264
VGAx IPPx 50 IPNx - + 500 PrA 6dB + 6dB - VOHx VOLx
50 IPNx
+
GNHx PULSE GENERATOR OUT
GNLO
VOCM
OFSx
GNHx
GNLO
VOCM
OFSx
07736-135
50
50
Figure 99. Pulse Response to VGAx, VGAIN = 0.7 V (See Figure 55 and Figure 57)
OSCILLOSCOPE PULSE GENERATOR CH1 50 50 CH2
Figure 102. OFSx Pulse Response (See Figure 60)
OSCILLOSCOPE OUT 50 PULSE GENERATOR 50
OUT 50
CH1
DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOLx 500 VOHx 500
07736-136
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VOLx CL 500
Figure 100. Pulse Response to Differential Outputs, VGAIN = 0.7 V (See Figure 56 and Figure 58)
Figure 103. Pulse Response to VGAx for Various Capacitive Loads, VGAIN = 0.7 V (See Figure 61)
Rev. 0 | Page 25 of 40
07736-122
GNHx
GNLO
VOCM
OFSx
GNHx
GNLO
VOCM
OFSx
07736-121
AD8264
OSCILLOSCOPE
OSCILLOSCOPE OUT 50 PULSE GENERATOR 50
OUT
CH1
SIGNAL GENERATOR 50
CH1 DIFFERENTIAL PROBE
50 OPPx
DIFFERENTIAL PROBE
AD8264
VGAx IPPx 50 IPNx
CL CL
07736-123
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOLx 500 VOHx 500 GNHx GNLO VOCM OFSx
+ -
PrA 6dB
+ 6dB -
VOLx
VOHx
Figure 104. Pulse Response to Differential Output for Various Capacitive Loads, VGAIN = 0.7 V (See Figure 62)
Figure 107. Preamp Overdrive Recovery (See Figure 66)
OSCILLOSCOPE
OSCILLOSCOPE OUT 50 PULSE GENERATOR 50
OUT
CH1
SIGNAL GENERATOR 50
CH1
50
DIFFERENTIAL PROBE
DIFFERENTIAL PROBE
AD8264
VGAx IPPx + - PrA 6dB VOLx 6dB -
CL
07736-127
07736-124
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VOLx 10 500 CL 10 500 GNHx GNLO VOCM OFSx
50 IPNx
+
VOHx
GNHx
GNLO
VOCM
OFSx
Figure 105. Pulse Response to Differential Output for Various Capacitive Loads with Series R = 10 , VGAIN = 0.7 V (See Figure 63)
Figure 108. VGA Overdrive Recovery, VGAIN = 0.7 V (See Figure 67)
OSCILLOSCOPE SIGNAL GENERATOR 50 50 CH1 CH2 DIFFERENTIAL PROBE
OUT 50
AD8264
VGAx IPPx 50 IPNx - + PrA 6dB + 6dB - VOHx VOLx
500
500
500 GNHx PULSE GENERATOR OUT
07736-125
GNLO
VOCM
OFSx
50
Figure 106. Gain Response to VGAx or Differential Output (See Figure 64 and Figure 65)
Rev. 0 | Page 26 of 40
07736-126
GNHx
GNLO
VOCM
OFSx
AD8264
OSCILLOSCOPE CH2 CH1 50 50 50 CH3
DIFFERENTIAL PROBE
DMM (+1) VPOS
DMM (-1) VNEG
AD8264
IPPx 50 IPNx - + PrA 6dB
VGAx 500 + 6dB - VOLx
500
AD8264
IPPx 50 IPNx
500
VGAx
+ -
PrA 6dB
+ 6dB -
VOLx
VOHx
VS
07736-108
VOHx
GNHx
VGAIN
GNLO
VOCM
OFSx
Figure 109. PSRR (See Figure 68 and Figure 69)
Figure 110. Quiescent Supply Current (See Figure 70)
Rev. 0 | Page 27 of 40
07736-109
VSUPPLY
GNHx
GNLO
VOCM
OFSx
AD8264 THEORY OF OPERATION
OVERVIEW
The AD8264 is a dc-coupled quad channel VGA with a fixed gain-of-2 (6 dB) preamplifier and a single-ended-to-differential output amplifier with level shift capability that can be used as an ADC driver. Figure 111 shows a representative block diagram of a single channel; all four channels are identical. The supply can operate from 2.5 V to 5 V. The primary application is as a pulse processor for medical positron emission tomography (PET) imaging; however, the part is useful for any dc-coupled application that can benefit from variable gain. The signal chain consists of three fundamental stages: the preamplifier, the variable gain amplifier, and the differential output buffer amplifier. The preamplifier has an internally fixed gain-of-2 (6 dB). The VGA comprises an attenuator that provides 0 dB to 24 dB of attenuation, followed by a fixed gain 18 dB (8x) amplifier. The single-ended VGA output is connected directly to the noninverting input of the differential output (post) amplifier, which has a differential fixed gain-of-2 (6 dB). The gain range from the preamp input to the VGA output is 0 dB to 24 dB. The aggregate gain range from preamp input to the differential postamplifier output is 6 dB to 30 dB. The ideal gain equation for the gain from the single-ended input to the output is VGAIN = VGNHx - VGNLO (1)
VGA
The VGA has a voltage feedback architecture and uses analog control to vary the gain. Its low gain range helps to maintain low offset and is intended for gain trim applications. The offset of the preamp and the VGA are trimmed; therefore, the maximum input referred offset is <0.5 mV over temperature (see Figure 26). Keeping the gain of each stage relatively low also allows the bandwidth to stay high. The gain of the VGA is adjusted using the fully differential control inputs, GNHx and GNLO. The GNLO pin is internally connected to all four channels and must be biased externally. Under typical conditions, the GNLO pin is grounded. The gain high control pins (GNHx) are independent for each channel. The gain slope is nominally 20 dB/V. With GNLO connected to ground, each GNHx input can have a voltage applied from VNEG to VPOS without gain foldover. To make use of the full gain range of the VGA, the nominal gain control voltage needed at GNHx is 0.65 V relative to the voltage applied to GNLO. At the lowest supply voltage of 2.5 V, the pin GNLO should always be grounded. With increasing supply, the common-mode range of the gain control interface increases. This means that GNLO can be anywhere within 1.2 V at 3.3 V supplies and 2.8 V at 5 V supplies.
Table 5. Gain Control Input Range
Supply Voltage (V) 5 3.3 2.5 GNLO Voltage Range (V) 2.8 1.2 0 VGAIN Range (V) 0.65 0.65 0.65
dB Gain = 20 x VGAIN + ICPT V
(2)
The ideal value for ICPT, or the intercept, is defined at VGAIN = 0 V. The ICPT for the VGA output and differential amplifier outputs equals 12.1 dB and 18.1 dB, respectively. The actual intercept varies with any additional gain or loss along the signal path. The measured values are both approximately 0.2 dB low.
PREAMP
The preamplifier is a current feedback amplifier, designed to drive the internal 100 gain setting resistors and the resistive attenuator, which together result in a nominal load to the preamplifier of about 113 . Normally, the negative preamp input, IPNx, is not connected externally. The positive input IPPx is the high impedance input of the current feedback amp. Note that, at the largest supply voltage of 5 V, the input signal can become so large that the preamplifier output cannot deliver the required current to drive the 113 load and, therefore, limits at 6 V p-p. This means that the input limits at 3 V p-p. The short-circuit input referred noise at maximum VGA gain is about 2.3 nV/Hz, and this accounts for all of the amplifiers and gain setting resistors. When measuring the input referred noise from the VGA output, the number is slightly lower at 2.1 nV/Hz because the noise of the postamplifier is not included in the noise calculation.
For example, at 3.3 V supplies, the outputs of a single-supply unipolar DAC, such as the 10-bit, 4-channel AD5314, can be used to drive the GNHx pins directly, in conjunction with using the ADR318 1.8 V reference to bias the GNLO pin at VREF/2 = 0.9. Because the GNLO pin sources only about 1.2 A for the four channels (~300 nA per channel, the same as for the GNHx pins), a simple resistive divider is generally adequate to set the voltage at the GNLO input.
Rev. 0 | Page 28 of 40
AD8264
COMPOSITE GAIN IS +6dB TO +30dB OPPx NONINVERTING AMPLIFIER INPUT IPPx 1 IPNx INVERTING AMPLIFIER INPUT (NOT USED) POWER SUPPLIES VPOS VNEG BIAS 1k PREAMP 6dB (2x) + ATTENUATOR - -24dB TO 0dB GAIN INTERFACE PREAMP OUTPUT (NOT USED) FIXED GAIN VGA AMPLIFIER 18dB (8x) VGAx SINGLE-ENDED HS VGA OUTPUT 3 DIFFERENTIAL OUTPUT AMPLIFIER 6dB (2x) 1k 747 107 2k 2k
VOLx
100 100
2 INTERPOLATOR
VOHx
DIFFERENTIAL VGA OUTPUT
COMM
GNHx
GNLO
VOCM
OFSx
DIFFERENTIAL GAIN CONTROL INPUTS 1 1.2V p-p MAX @ 2.5V 2V p-p MAX @ 3.5V TO 3.3V 3V p-p MAX@ 5V (PREAMP DRIVE LIMITED) 2.3nV/Hz 2 DIFFERENTIAL OUTPUT NEVER LIMITS BECAUSE VGA LIMITS FIRST. DIFFERENTIAL OUTPUT SWING = 2x VGA OUT 5.2V p-p MAX @ 2.5V 8V p-p MAX @ 3.5V TO 3.3V 15V p-p MAX @ 5V 73nV/Hz
OUTPUT COMMON-MODE VOLTAGE ADJUSTMENT
OFFSET ADJUST
3 2.6V p-p MAX @ 2.5V 4V p-p MAX @ 3.5V TO 3.3V 7.5V p-p MAX @ 5V 34nV/Hz
07736-081
Figure 111. Single-Channel Block Diagram
POST AMPLIFIER
From the preamp input to the VGA output (VGAx), the gain is noninverting. As can be seen in Figure 111, the VGAx pins drive the positive input of the differential amplifier. The gain is inverting from the input of the preamp to the output pin at VOLx, and the gain is noninverting to the output VOHx. Other than the input from VGAx, each differential amplifier has two additional inputs: VOCM and OFSx. A common VOCM pin is shared among all four postamplifiers, while separate OFSx pins are provided for each channel.
If dc offset is not desired, then the OFSx pins should be connected to ground. However, the OFSx pins can also be used as separate inputs if the user wants this function.
NOISE
At maximum gain, the preamplifier is the primary contributor of noise and results in a differential output referred noise of roughly 73 nV/Hz. The noise at the VGAx outputs is 34 nV/Hz, and because of the gain-of-2, the VGA output noise is amplified by 6 dB to 68 nV/Hz. The differential amplifier, including the gain setting resistors, contributes another 26 nV/Hz, and the rms sum results in a total noise of 73 nV/Hz. At the lowest gain, the noise at the VGA output is approximately 19 nV/Hz, and when multiplied by two, it results in 38 nV/Hz at the differential output; again, rms summing this with the 26 nV/Hz of the differential amplifier causes the total output referred noise to be approximately 46 nV/Hz. The input referred noise to the preamplifier at maximum gain is 2.3 nV/Hz and increases with decreasing gain. Note that all noise numbers include the necessary gain setting resistors.
VOCM Pin
The VOCM pin sets the common-mode voltage of the differential output and must be biased by an external voltage. When driving a dc-coupled ADC, the voltage typically comes from the ADC reference, as shown in the Applications Information section. If dc level shift is not necessary, the VOCM pin is connected to ground.
OFSx Pins
The OFSx pins are the inverting inputs of the differential post amplifiers and can be used to prebias a differential dc offset at the output. This is very useful when the input is a unipolar pulse because the user can set up the gain and the offset in such a way as to optimally map a unipolar pulse into the full-scale input of an ADC, while dc coupling throughout.
Rev. 0 | Page 29 of 40
AD8264 APPLICATIONS INFORMATION
A LOW CHANNEL COUNT APPLICATION CONCEPT USING A DISCRETE REFERENCE
The AD8264 is particularly well suited for use in the analog front end of medical PET imaging systems. Figure 112 shows how the AD8264 may be used with the AD5314 (a 4-channel, 10-bit DAC) and the AD9222/AD9228 (an octal or quad, 12-bit ADC, respectively). The DAC sets the gain of the AD8264. Note that the full gain span of 24 dB is achieved with this setup because the gain control input range of the AD8264 is very close to 1.25 V. The GNLO pin must offset by 1.25/2 = 625 mV because the gain control input is bipolar around the voltage applied at GNLO. This is done with two 1 k, 1% resistors. The approximately 1 A of bias current flowing from the GNLO pin does not contribute a significant error because the basic gain error of the AD8264 is the limiting factor. The ADR127 1.25 V precision reference with an input of 3.3 V can supply -2 mA to +5 mA from -40C to +125C, which is sufficient to drive both the resistive divider and the REFIN pin of the AD5314. The AD5314 is based on the string DAC concept, which means that the REFIN pin looks like a resistor that is nominally 45 k; this results in a current draw of 1.25V/45 k = 28 A. Even at the lowest specified resistance of 37 k, this is still only a current of 34 A. Therefore, the total current draw from the ADR127 is the 625 A of the resistive divider plus ~30 A, which equals ~655 A, well below the 5 mA maximum current.
ADR127
1 NC +3.3V 2 GND 3 VIN NC 6 NC 5 1.25V V xD VOUT = REFIN 2N +3.3V REFIN VDD VOUT RANGE = 0V TO 1.25V EACH VOUTA VOUTB VOUTC VOUTD
Figure 112 also includes the DAC output equation, which indicates that the output can vary between 0 V and VREF = 1.25 V. The output of the AD8264 is ideal to drive an ADC like the 1.8 V quad-channel AD9228. If eight channels are needed, two AD8264s with the octal AD9222 ADC achieve the same thing. The same resistive divider can be used for two AD8264s because the bias current flowing is now ~2 A, but this still only introduces an error of 1 mV with ideally matched resistors. With 20 dB/V gain scaling, this is a gain error of only 0.02 dB, which is much smaller than the fundamental gain error of the AD8264 (typically ~0.2 dB). The single-ended-to-differential amplifier of the AD8264 amplifies the VGA output signal by 6 dB and can provide the required dc bias of the AD9222/AD9228, as shown in Figure 112. The ADC is connected with the default internal reference because the SENSE pin is grounded. With this connection, the AD9222/ AD9228 VREF pin is an output that provides 1 V; this is then connected to the VOCM input of the AD8264, which sets the output common-mode voltage of the VOHx and VOLx pins to 1 V. This voltage is very close to the recommended optimal value of VDD/2 = 0.9 V. With this configuration, the ADC inputs are set to a full-scale (FS) of 2 V p-p. Note that the ADC VREF should not drive many loads; therefore, for multiple AD8264s, the VREF should be buffered.
0.1F 10F
625A
VOUT 4
1F
625mV
1k 1% 1k 1% 0.1F
DAC AD5314
GND
+3.3V RS RTERM VPOS IPPx
~1A
GNLO
~250nA EACH GNH1 GNH2 GNH3 GNH4 VGAx VGA OUTPUTS TO OTHER SIGNAL PROCESSING RFILT FS = 2V p-p VIN - x VDD ADC AD9222/ AD9228 GND +1.8V
AD8264
VNEG VOCM OFSx VOHx VOLx -3.3V 10F 0.1F
CFILT RFILT
VIN + x VREF SENSE
07736-082
OUTPUT COMMON-MODE VOLTAGE = 1V VOHx = 1V, VOLx = 1V; VOFS = 0V
SENSE GROUNDED: VREF = 1V
Figure 112. Application Concept of the AD8264 with the AD5314 10-Bit DAC and the AD9222/AD9228 12-Bit ADC
Rev. 0 | Page 30 of 40
AD8264
A DC CONNECTED CONCEPT EXAMPLE
The dc connected concept example in Figure 113 is an application with the 40-channel AD5381, 3 V, 12-bit DAC. The main difference between this example and Figure 112 is that, for the same ADR127 1.25 V reference, the full-scale output of the DAC is from 0 V to 2 x VREFIN = 2.5 V. Two options for gain control include the following:
*
Figure 113 shows how the AD8264 is connected in a PET application. The PMT generates a negative-going current pulse that results in a voltage pulse at the preamplifier input and a differential output pulse on VOLx and VOHx. To fully appreciate the advantages of the AD8264, note the common-mode and polarity conversion afforded. The AD9228, as with most modern ADCs, is a low voltage, single-polarity device. Recall that the PMT is a high voltage device that yields a negative pulse. To map the pulse to the input range of the ADC, the pulse must be inverted, shifted, and amplified to the full input range of the ADC. This is done by using the gain control, signal offset, and common-mode features of the AD8264. The full-scale input of the converter is 0 V to 2 V, with a commonmode of 1 V. Match the VOCM voltage of the AD8264 to the ADC common mode (VREF = 1 V), and the two devices can be connected directly using an appropriate level of the antialiasing filter. The PMT signal is 0 V to -0.1 V. With a gain of 20x (26 dB), the AD8264 output signal range is 2 V p-p. Prebias the signal negative by -0.5 V using the AD8264 OFSx inputs, which sets VOHx = 1.5 V and VOLx = 0.5 V for VOCM = 1 V. The output is perfectly matched to the input of the ADC. Note that, by connecting VOLx to the positive ADC input and VOHx to the negative ADC input, the negative input pulse is inverted automatically. The VGAx output is still a negative pulse, amplified by 20 dB for this example.
*
Use the same circuit as in Figure 112 but use only half the DAC output voltage from 0 V to 1.25 V. This is the simplest solution, requiring the fewest extra components. Note that the overall gain resolution increases by one bit to 11 bits over the 10-bit AD5314. Ground GNLO and scale the DAC output so that the GNHx inputs vary from -0.652 V to +0.625 V. Figure 113 shows a possible circuit implementation using a divider between the DAC output and a -1.25 V reference.
GNLO cannot simply be increased to 1.25 V because, for a given supply voltage, GNLO has a limited voltage range to achieve the full gain span (see Table 5). However, a third possibility is to use another voltage that is between 1.2 V and 625 mV on GNLO, such as 1 V. In this case, the DAC must vary from 0.375 V to 1.625 V to achieve the fully specified gain range. Note the gain limits when the differential gain control exceeds 0.625 V, either to 6 dB or to 30 dB. If the differential gain control input voltage is exceeded, no gain foldover occurs.
ADR127
1 NC +3.3V 2 GND NC 6 NC 5 VREF = 1.25V 1F +3.3V 10F REFIN VDD
0.1F
3 VIN VOUT 4
VOUT =
2 x VREFIN x D 2N VOLTAGE FROM DAC AD5381 = 0 TO 2.5V VOUT0 VOUT39 VARIES FROM 12.5 TO 32.5A 49.9k GNH4 ~250nA 1% -625mV TO 49.9k +625mV 1% 49.9k 1% -1.25V +3.3V 49.9k 1% GNH1 0.1F 49.9k 1% 0.1F
VOUT RANGE = 0V TO 1.25V EACH VOUT0 VOUT1 VOUT2 VOUT4
DAC AD5381
EXAMPLE 0V SCALE CIRCUIT -0.1V 100 PMT
GND VOUT39 +3.3V VPOS IPPx GNLO ~250nA EACH GNH1 GNH2 GNH3 GNH4 VGAx VNEG VOCM OFSx VOHx VOLx RFILT -3.3V CFILT SCALE CIRCUIT SCALE CIRCUIT SCALE CIRCUIT SCALE CIRCUIT VGA OUTPUTS TO OTHER SIGNAL PROCESSING FS = 2V p-p VIN + x
TO 9 OTHER AD8264s
VREF = 1.25V 49.9k 1%
SCALE CIRCUIT 10F 0.1F
AD8264
+1.8V
AD8663
-3.3V
ADC VDD AD9222/ AD9228 GND
VOFS = -0.5V
RFILT 10F 0.1F
VIN - x VREF SENSE
07736-083
OUTPUT COMMON-MODE VOLTAGE = 1V VOHx = 1.5V, VOLx = 0.5V; VOFx = -0.5V
SENSE GROUNDED: VREF = 1V
Figure 113. Concept Application of AD8264 with 40-Channel AD5381 12-Bit, 3 V DAC and AD9222/AD9228 12-Bit ADC
Rev. 0 | Page 31 of 40
AD8264
+3.3V +3.3V
DVDD AVDDx
VOUT RANGE = 0V TO 1.25V EACH VOUT0 VOUT1 VOUT3 VOUT4 VOUT39
TO 9 OTHER AD8264s
+3.3V
-3.3V VNEG VOHx VOLx
VGA OUTPUTS TO OTHER SIGNAL PROCESSING
TO SWITCHING POWER SUPPLY
PARALLEL INTERFACE TO PC CONTROL
EVAL BOARD +2.5V DGND AGNDx
AD5381
DAC
GNH1 VPOS GNH2 GNH3 GNH4
-INx +INx
VPOS
AD8264 VGA
EVAL BOARD IPPx GNLO VGAx OFSx VOCM
EVAL KIT
AD9228
ADC
+1.0V
VREF
USB 2.0 TO PC ADI VISUAL ANALOG ANALYSIS SOFTWARE
REFIN (ON BOARD)
INPUT EXAMPLES
0V -0.1V PULSE GENERATOR INx GNLO = 625mV OFSx = -0.5V VOCM = 1.0V
VOLTAGE (V)
0
50
100 150 200 SAMPLES
250
300
Figure 114. Evaluation Setup for DC-Coupled Analog Front-End Pulse Processing Application Using the AD8264
Figure 115. AD5381 Evaluation Software
A convenient method of verifying and customizing the signal chains shown in Figure 112 or Figure 113 is by ordering the corresponding evaluation boards available on www.analog.com. The AD8264-EVALZ is a platform through which the user can quickly become familiar with the features and performance capabilities of the AD8264. See the Evaluation Board section for more information. The EVAL-AD5381EB (40-channel DAC) includes a parallel PC interface and software evaluation program to control the DAC. The AD5381evaluation software allows the user to configure
and program such DAC parameters as input codes, offset level, and output range based on a 2.5 V or 1.25 V reference. For example, as shown in Figure 114, the reference can be set to 1.25 V, with a 0 V to 1.25 V output range to drive the GNHx inputs. The ADC evaluation kit includes the AD9228-65EBZ board and HSC-ADC-FIFO5 board to decode the ADC output. It also leverages the capabilities of VisualAnalog(R), powerful simulation and data analysis software that enables the user to run FFTs and to do real-time capture of the output levels.
Rev. 0 | Page 32 of 40
07736-085
07736-084
1.0 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0
AD8264
+3.3V +3.3V
DVDD AVDDx
VOUT RANGE = 0V TO 1.25V EACH VOUT0 VOUT1 VOUT3 VOUT4 VOUT39
+3.3V
-3.3V VNEG VOHx VOLx
VGA OUTPUTS TO OTHER SIGNAL PROCESSING
TO SWITCHING POWER SUPPLY
PARALLEL INTERFACE TO PC CONTROL
EVAL BOARD +2.5V DGND AGNDx
AD5381
DAC
TO 9 OTHER AD8264S
GNH1 VPOS GNH2 GNH3 GNH4
-INx +INx
VPOS
AD8264 VGA
EVAL BOARD IPPx GNLO VGAx OFSx VOCM
EVAL KIT
AD9228
ADC
+1.0V
VREF
USB 2.0 TO PC ADI VISUAL ANALOG ANALYSIS SOFTWARE
REFIN (ON BOARD)
0 -15 -30 -45 -60 -75 -90 -105 -120 -135 -150
INPUT EXAMPLES
GNLO = 625mV INx AC SOURCE
VOCM = 1.0V
+ 2
3
4
07736-086
1.5M 3.0M 4.5M 6.0M 7.5M 9.0M 10.5M
Figure 116. Evaluation Setup for AC Signal Processing Application Using the AD8264
Rev. 0 | Page 33 of 40
AD8264 EVALUATION BOARD
Analog Devices, Inc. provides evaluation boards to customers as a support service so that the circuit designer can become familiar with the device in the most efficient way possible. The AD8264 evaluation board provides a fast, easy, and convenient means to assess the performance of the AD8264 before going through the hassle and expense of design and layout of a custom board. The board is shipped fully assembled and tested, and it provides basic functionality as shipped. Standard connectors enable the user to attach standard lab test equipment without having to wait for the rest of the design to be completed. Figure 117 shows a digital image of the top view, and Figure 118 shows the schematic diagram of the AD8264 evaluation board. The printed circuit board (PCB) artwork for all conductor and silkscreen layers is shown in Figure 119 to Figure 124. A description of a typical test setup can be found in the Applications Information section. The PCB artwork can be used as a guide for circuit layout and placement of parts. This is particularly useful for multiple function circuits with many pins, requiring multiple passive components.
CONNECTING AND USING THE AD8264-EVALZ
The AD8264 operates with bipolar power supplies from 2.5 V dc to 5 V dc. Make sure the current capacity is 400 mA. Connect a ground reference from the supplies to any of the black test loops, the positive supply to the red test loop (+V), and the negative supply to the blue test loop (-V). Notice that the board is shipped with jumpers installed on the 2-pin headers marked GN1_2, GN3_4, OFS_12, OFS_34, and VOCM. If these jumpers are missing, the offset and commonmode functions float high, substantially increasing the quiescent current of the board. Apply input signals to any of the preamps at the SMA connectors, IN1 through IN4. These connectors are terminated with 50 to accommodate typical signal generator analyzer voltage source impedances. The gain of the AD8264 preamps is fixed at 6 dB (2x) and can be monitored at the SMA connectors, OP1_2 and OP3_4, if desired. Note that there are output selector switches for each pair of preamps and 453 resistors in series with the preamp outputs.
Figure 117. Digital Image of the AD8264-EVALZ (Top View)
Rev. 0 | Page 34 of 40
07736-087
AD8264
GN12 GND1 GND2 GND3 GND4 GND5 GND6 +V +V -V -V +
OFS12
C34 10F R10 DNI GN1_2 IN_1
IN1
R32 DNI GNLO
L1 FB C20 0.1F
L2 FB C19 0.1F
C33 + 10F R9 DNI OFS_12
R51 0 R11 49.9 OPP12 R24 DNI
1 40
C24 0.1F R49 R86 0 0 39 38 37 IPP1 COMM GNH1 GNH2 R47 R48 0 0 34 33 32 OFS1 OFS2 VNEG VGA1 31 VGA1 R55 0 R56 0 R58 0 R57 0 VOUT_2 R69 453 R67 453 VGA3 VOUT_3
VGA2
R1 453
VGA1
36 GNLO
35 VPOS
OP1_2
R7 OP12 453
IPN1 OPP1 OPP2 IPN2
PIN 0 EXPOSED PADDLE
R31 DNI IN_2 R73 0 R45 49.9
VOL1 VOH1 VOH2 VOL2 VGA2 VGA3 VOL3 VOH3 VOH4 COMM VOCM VNEG VPOS GNH4 GNH3 VGA4 OFS4 OFS3 VOL4
30 29 28
2 3
VOUT_1
IN2
R23 R22 DNI DNI
4
27
IN_3
IN3
R78 0
R46 49.9 R25 DNI R20 DNI
5 IPP2 6 IPP3 7 IPN3 8
26 VGA2 25 VGA3 24 23
22 21
PIN 0: EXPOSED PADDLE
R66 0 R65 0 R63 0 R64 0 R8 453
OP3_4
R6 453
OP34 R19 DNI OPP34
R29 DNI
OPP3
9 OPP4 10
IPN4 IPP4
VOUT_4
IN_4 IN4 R17 49.9 R72 0 R12 DNI GN3_4
11
12
13 R80 0
14
15
16
17
R79 0
C23 0.1F C22 0.1F
18 R70 0
19 R71 0
20
VGA4
VGA4 R16 DNI OFS_34
R28 DNI VOCM
C21 0.1F
L3 FB VOCM +V -V
L4 FB OFS34
07736-088
GN34
Figure 118. AD8264-EVALZ Schematic
The SMA connectors, VGA1 through VGA4, enable signal monitoring at these nodes, with 453 resistors for protecting the device. These resistors can be shorted at the discretion of the user if wide bandwidth is desired. The differential outputs are provided with 0.1" spacing 2-pin headers, which fit the low capacitance Tektronix differential scope probe P6045 model. Note that the gain control input of the AD8264 is differential. Each channel has its own gain control pin (GNHx); however, pairs of pins are connected together on the evaluation board and connected to a test loop. The 2-pin headers are provided for jumpers to connect the gain pins to ground, preventing the
quiescent gain control voltage at the GNHx pins from floating high. The low sides of the gain controls for each channel are internally connected in the AD8264, and a 2-pin header with jumper is provided to connect this pin (GNLO) to ground as well. A similar arrangement of 2-pin headers is provided for the output offset voltage. As shipped, the offset pins are connected to ground, preventing the pins from floating high. For connecting to an ADC, remove the jumpers at the OF1_2 and OF3_4 headers and connect the appropriate offset voltage at the test loops, OF12 and OF34. If the VOCM pin is buffered, it can be connected to the reference of the ADC.
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AD8264
07736-089
Figure 119. Component Side Assembly
Figure 121. Component Side Silk Screen
07736-091
07736-090
Figure 120. Component Side Copper
Figure 122. Secondary Side Copper
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07736-092
AD8264
07736-093
Figure 123. Ground Plane
Figure 124. Power Plane
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07736-094
AD8264 OUTLINE DIMENSIONS
6.00 BSC SQ 0.60 MAX 0.60 MAX
31 30 40 1
PIN 1 INDICATOR
PIN 1 INDICATOR
TOP VIEW
5.75 BSC SQ
0.50 BSC 0.50 0.40 0.30
EXPOSED PAD
(BOT TOM VIEW)
4.25 4.10 SQ 3.95
10
21 20
11
0.25 MIN 4.50 REF
12 MAX
0.80 MAX 0.65 TYP 0.05 MAX 0.02 NOM
1.00 0.85 0.80
COMPLIANT TO JEDEC STANDARDS MO-220-VJJD-2
Figure 125. 40-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 6 mm x 6 mm Body, Very Thin Quad (CP-40-1) Dimensions shown in millimeters
ORDERING GUIDE
Model AD8264ACPZ 1 AD8264ACPZ-R71 AD8264ACPZ-RL1 AD8264-EVALZ1
1
Temperature Range -40C to +85C -40C to +85C -40C to +85C
Package Description 40-Lead LFCSP_VQ 40-Lead LFCSP_VQ, 7" Tape and Reel 40-Lead LFCSP_VQ, 13" Tape and Reel Evaluation Board
Package Option CP-40-1 CP-40-1 CP-40-1
072108-A
SEATING PLANE
0.30 0.23 0.18
0.20 REF
COPLANARITY 0.08
FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET.
Branding H1V H1V H1V
Z = RoHS Compliant Part.
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AD8264 NOTES
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AD8264 NOTES
(c)2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07736-0-5/09(0)
Rev. 0 | Page 40 of 40

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