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FEATURES High Speed 80 MHz Bandwidth (3 dB, G = +1) 75 MHz Bandwidth (3 dB, G = +2) 1000 V/ s Slew Rate 50 ns Settling Time to 0.1% (VO = 10 V Step) Ideal for Video Applications 30 MHz Bandwidth (0.1 dB, G = +2) 0.02% Differential Gain 0.04 Differential Phase Low Noise 2.9 nV/Hz Input Voltage Noise 13 pA/Hz Inverting Input Current Noise Low Power 8.0 mA Supply Current max 2.1 mA Supply Current (Power-Down Mode) High Performance Disable Function Turn-Off Time 100 ns Break Before Make Guaranteed Input to Output Isolation of 64 dB (OFF State) Flexible Operation Specified for 5 V and 15 V Operation 2.9 V Output Swing Into a 150 Load (VS = 5 V) APPLICATIONS Professional Video Cameras Multimedia Systems NTSC, PAL & SECAM Compatible Systems Video Line Driver ADC/DAC Buffer DC Restoration Circuits
Low Power Video Op Amp with Disable AD810
CONNECTION DIAGRAM 8-Pin Plastic Mini-DIP (N), SOIC (R) and Cerdip (Q) Packages
OFFSET NULL -IN +IN -VS 1 2 3 4 TOP VIEW
AD810
8 7 6 5
DISABLE +V S OUTPUT OFFSET NULL
PRODUCT DESCRIPTION
The AD810 is a composite and HDTV compatible, current feedback, video operational amplifier, ideal for use in systems such as multimedia, digital tape recorders and video cameras. The 0.1 dB flatness specification at bandwidth of 30 MHz (G = +2) and the differential gain and phase of 0.02% and 0.04 (NTSC) make the AD810 ideal for any broadcast quality video system. All these specifications are under load conditions of 150 (one 75 back terminated cable). The AD810 is ideal for power sensitive applications such as video cameras, offering a low power supply current of 8.0 mA max. The disable feature reduces the power supply current to only 2.1 mA, while the amplifier is not in use, to conserve power. Furthermore the AD810 is specified over a power supply range of 5 V to 15 V. The AD810 works well as an ADC or DAC buffer in video systems due to its unity gain bandwidth of 80 MHz. Because the AD810 is a transimpedance amplifier, this bandwidth can be maintained over a wide range of gains while featuring a low noise of 2.9 nV/Hz for wide dynamic range applications.
0.10 0.20 GAIN = +2 RF = 715 RL = 150 fC = 3.58MHz 100 IRE MODULATED RAMP 0.18 0.16 0.14 0.12 0.10 GAIN PHASE 0.08 0.06 0.04 0.02 0 15
0
0.09
PHASE SHIFT - Degrees
PHASE
-90 1 -135 VS = 15V -180 GAIN -1 2.5V -2 VS = 15V -3 -4 -5 1 10 100 FREQUENCY - MHz 1000 5V -270 5V -225
DIFFERENTIAL GAIN - %
-45
0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01
CLOSED-LOOP GAIN - dB
0
2.5V
0 5 6 7 8 9 10 11 12 13 14 SUPPLY VOLTAGE - Volts
Closed-Loop Gain and Phase vs. Frequency, G = +2, RL = 150, RF = 715
Differential Gain and Phase vs. Supply Voltage
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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703
DIFFERENTIAL PHASE - Degrees
GAIN = +2 RL = 150
AD810-SPECIFICATIONS (@ T = +25 C and V =
A S
15 V dc, RL = 150
Min 40 55 40 50 13 15
unless otherwise noted)
Min 40 55 40 50 13 15 AD810S1 Typ Max 50 75 80 65 22 30 16 350 1000 50 125 0.02 0.04 0.04 0.045 -61 6 7.5 1.5 4 15 0.8 2 1.0 0.2 80 72 56 50 0.4 60 0.3 3.5 1.0 100 88 64 60 0.1 72 0.05 2.9 13 1.5 2.5 12 2.5 12.5 12 30 3 13 2.9 12.9 150 60 15 2.5 10 40 2 6 15 Units MHz MHz MHz MHz MHz MHz MHz V/s V/s ns ns % % Degrees Degrees dBc mV mV V/C A A M M dB dB dB dB A/V dB A/V nV/Hz pA/Hz pA/Hz V V V V V mA mA M pF dB
Parameter DYNAMIC PERFORMANCE 3 dB Bandwidth
Conditions (G = +2) RFB = 715 (G = +2) RFB = 715 (G = +1) RFB = 1000 (G = +10) RFB = 270 (G = +2) RFB = 715 (G = +2) RFB = 715 VO = 20 V p-p, RL = 400 RL = 150 RL = 400 10 V Step, G = -1 10 V Step, G = -1 f = 3.58 MHz f - 3.58 MHz f = 3.58 MHz f = 3.58 MHz f = 10 MHz, VO = 2 V p-p RL = 400 , G = +2 TMIN-TMAX
VS 5 V 15 V 15 V 15 V 5 V 15 V 15 V 5 V 15 V 15 V 15 V 15 V 5 V 15 V 5 V 15 V 5 V, 15 V 5 V, 15 V
AD810A Typ Max 50 75 80 65 22 30 16 350 1000 50 125 0.02 0.04 0.04 0.045 -61 1.5 2 7 0.7 2
0.1 dB Bandwidth Full Power Bandwidth Slew Rate2 Settling Time to 0.1% Settling Time to 0.01% Differential Gain Differential Phase Total Harmonic Distortion INPUT OFFSET VOLTAGE Offset Voltage Drift INPUT BIAS CURRENT -Input +Input OPEN-LOOP TRANSRESISTANCE OPEN-LOOP DC VOLTAGE GAIN COMMON-MODE REJECTION VOS Input Current POWER SUPPLY REJECTION VOS Input Current INPUT VOLTAGE NOISE INPUT CURRENT NOISE INPUT COMMON-MODE VOLTAGE RANGE OUTPUT CHARACTERISTICS Output Voltage Swing3
0.05 0.07 0.07 0.08
0.05 0.07 0.07 0.08
TMIN-TMAX TMIN-TMAX TMIN-TMAX VO = 10 V, RL = 400 VO = 2.5 V, RL = 100 TMIN-TMAX VO = 10 V, RL = 400 VO = 2.5 V, RL = 100 TMIN-TMAX VCM = 12 V VCM = 2.5 V TMIN-TMAX TMIN-TMAX TMIN-TMAX f = 1 kHz -IIN, f = 1 kHz +IIN, f = 1 kHz
5 V, 15 V 5 V, 15 V 15 V 5 V 15 V 5 V 15 V 5 V 5 V, 15 V 4.5 V to 18 V 65 5 V, 15 V 5 V, 15 V 5 V, 15 V 5 V 15 V 2.5 12 2.5 12.5 12 40 1.0 0.3 86 76 56 52
5 7.5
5 10
3.5 1.2 100 88 64 60 0.1 72 0.05 2.9 13 1.5 3.0 13 2.9 12.9 150 60 15
0.4
0.3
RL = 150 , TMIN-TMAX RL = 400 RL = 400 , TMIN-TMAX TMIN-TMAX Open Loop (5 MHz) +Input -Input +Input f = 5 MHz, See Figure 43 See Figure 43
Short-Circuit Current Output Current OUTPUT RESISTANCE INPUT CHARACTERISTICS Input Resistance Input Capacitance DISABLE CHARACTERISTICS4 OFF Isolation OFF Output Impedance
5 V 15 V 15 V 15 V 5 V, 15 V
15 V 15 V 15 V
2.5
10 40 2
64 (RF + RG) 13 pF
64 (RF+ RG) 13 pF
-2-
REV. A
AD810
Parameter Turn On Time Turn Off Time Disable Pin Current Min Disable Pin Current to Disable POWER SUPPLY Operating Range Quiescent Current TMIN-TMAX Power-Down Current
5
Conditions ZOUT = Low, See Figure 54 ZOUT = High Disable Pin = 0 V
VS
Min
AD810A Typ Max 170 100 50 290 30
Min
AD810S1 Typ Max 170 100 50 290 30
Units ns ns A A A
5 V 15 V 5 V, 15 V 2.5 3.0
75 400
75 400
TMIN-TMAX +25C to TMAX TMIN
5 V 15 V 5 V, 15 V 5 V 15 V
6.7 6.8 8.3 1.8 2.1
18 18 7.5 8.0 10.0 2.3 2.8
2.5 3.5 6.7 6.8 9 1.8 2.1
18 18 7.5 8.0 11.0 2.3 2.8
V V mA mA mA mA mA
NOTES 1 See Analog Devices Military Data Sheet for 883B Specifications. 2 Slew rate measurement is based on 10% to 90% rise time with the amplifier configured for a gain of -10. 3 Voltage Swing is defined as useful operating range, not the saturation range. 4 Disable guaranteed break before make. 5 Turn On Time is defined with 5 V supplies using complementary output CMOS to drive the disable pin. Specifications subject to change without notice.
TOTAL POWER DISSIPATION - Watts
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 V Internal Power Dissipation2 . . . . . . . Observe Derating Curves Output Short Circuit Duration . . . . Observe Derating Curves Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . . . VS Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . 6 V Storage Temperature Range Plastic DIP . . . . . . . . . . . . . . . . . . . . . . . . -65C to +125C Cerdip . . . . . . . . . . . . . . . . . . . . . . . . . . . -65C to +150C Small Outline IC . . . . . . . . . . . . . . . . . . . -65C to +125C Operating Temperature Range AD810A . . . . . . . . . . . . . . . . . . . . . . . . . . . -40C to +85C AD810S . . . . . . . . . . . . . . . . . . . . . . . . . . -55C to +125C Lead Temperature Range (Soldering 60 sec) . . . . . . . +300C
NOTES 1 Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and 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 raring conditions for extended periods may affect device reliability. 2 8-Pin Plastic Package: JA = 90C/Watt; 8-Pin Cerdip Package: JA = 110C/Watt; 8-Pin SOIC Package: JA = 150C/Watt.
ABSOLUTE MAXIMUM RATINGS 1
MAXIMUM POWER DISSIPATION
The maximum power that can be safely dissipated by the AD810 is limited by the associated rise in junction temperature. For the plastic packages, the maximum safe junction temperature is 145C. For the cerdip package, the maximum junction temperature is 175C. If these maximums are exceeded momentarily, proper circuit operation will be restored as soon as the die temperature is reduced. Leaving the device in the "overheated" condition for an extended period can result in device burnout. To ensure proper operation, it is important to observe the derating curves.
2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 -60 8-PIN SOIC -40 -20 0 20 40 60 80 8-PIN MINI-DIP
8-PIN CERDIP 8-PIN MINI-DIP
100
120
140
ESD SUSCEPTIBILITY
AMBIENT TEMPERATURE - C
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 volts, which readily accumulate on the human body and on test equipment, can discharge without detection. Although the AD810 features ESD protection circuitry, permanent damage may still occur on these devices if they are subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid any performance degradation or loss of functionality.
ORDERING GUIDE
Model AD810AN AD810AR AD810AR-REEL 5962-9313201MPA Temperature Range -40C to +85C -40C to +85C -40C to +85C -55C to +125C Package Description 8-Pin Plastic DIP 8-Pin Plastic SOIC 8-Pin Plastic SOIC 8-Pin Cerdip Package Option N-8 R-8 R-8 Q-8
Maximum Power Dissipation vs. Temperature
While the AD810 is internally short circuit protected, this may not be sufficient to guarantee that the maximum junction temperature is not exceeded under all conditions.
0.1F +VS 7 2 3 SEE TEXT 10k 1 5 6 0.1F
AD810
4 -VS
Offset Null Configuration
REV. A
-3-
AD810 -Typical Characteristics
MAGNITUDE OF THE OUTPUT VOLTAGE - Volts
20
MAGNITUDE OF THE OUTPUT VOLTAGE - Volts
20
15 NO LOAD 10
15 NO LOAD 10
RL = 150 5
RL = 150 5
0 0 5 10 15 SUPPLY VOLTAGE - Volts 20
0 0 5 10 15 SUPPLY VOLTAGE - Volts 20
Figure 1. Input Common-Mode Voltage Range vs. Supply Voltage
35
Figure 2. Output Voltage Swing vs. Supply
10
OUTPUT VOLTAGE - Volts p-p
30 15V SUPPLY
9
SUPPLY CURRENT - mA
25 20 15 10 5V SUPPLY 5
VS = 15V 8 VS = 5V 7
6
5
0 10
100 1k LOAD RESISTANCE - Ohms
10k
4 -60
-40
-20
0
20
40
60
80
100
120
140
JUNCTION TEMPERATURE - C
Figure 3. Output Voltage Swing vs. Load Resistance
Figure 4. Supply Current vs. Junction Temperature
10 8
10 8
INPUT BIAS CURRENT - A
6 NONINVERTING INPUT 4 2 0 -2 -4 -6 -8 -10 -60 -40 -20 20 40 60 80 100 120 140 INVERTING INPUT VS = 5V, 15V VS = 5V, 15V
INPUT OFFSET VOLTAGE - mV
6 4 VS = 5V 2 0 -2 -4 -6 -8 -10 -60 -40 -20 0 20 40 60 80 100 120 140 VS = 15V
0
JUNCTION TEMPERATURE - C
JUNCTION TEMPERATURE - C
Figure 5. Input Bias Current vs. Temperature
Figure 6. Input Offset Voltage vs. Junction Temperature
-4-
REV. A
Typical Characteristics- AD810
250
120
SHORT CIRCUIT CURRENT - mA
100
VS = 15V 150
OUTPUT CURRENT - mA
200
VS = 15V
80
60 VS = 5V 40
100
VS = 5V 50 -60 -40 -20 0 +20 +40 +60 +80 +100 +120 +140
20 -60 -40 -20 0 +20 +40 +60 +80 +100 +120 +140
JUNCTION TEMPERATURE - C
JUNCTION TEMPERATURE - C
Figure 7. Short Circuit Current vs. Temperature
Figure 8. Linear Output Current vs. Temperature
10.0
1M
CLOSED-LOOP OUTPUT RESISTANCE -
OUTPUT RESISTANCE -
GAIN = 2 1.0 RF = 715
VS = 5V
100k
10k
VS = 15V 0.1
1k
0.01 10k
100k
1M FREQUENCY - Hz
10M
100M
100 100k
1M FREQUENCY - Hz
10M
100M
Figure 9. Closed-Loop Output Resistance vs. Frequency
Figure 10. Output Resistance vs. Frequency, Disabled State
100 100 VS = 5V TO 15V
30 VS = 15V
OUTPUT VOLTAGE - Volts p-p
25
20
OUTPUT LEVEL FOR 3% THD RL = 400
INVERTING INPUT CURRENT NOISE 10 10
15
10 VS = 5V 5
VOLTAGE NOISE
NONINVERTING INPUT CURRENT NOISE 1 10 1 100k
0 100k
1M 10M FREQUENCY - Hz
100M
100
1k FREQUENCY - Hz
10k
Figure 11. Large Signal Frequency Response
Figure 12. Input Voltage and Current Noise vs. Frequency
REV. A
-5-
CURRENT NOISE - pA/ Hz
VOLTAGE NOISE - nV/ Hz
AD810 -Typical Characteristics
100 90 80 70 60 50 40 30 20 10k
80 70 RF = 715 AV = +2
COMMON-MODE REJECTION - dB
POWER SUPPLY REJECTION - dB
60 50 40 30 20 10 CURVES ARE FOR WORST CASE CONDITION WHERE ONE SUPPLY IS VARIED WHILE THE OTHER IS HELD CONSTANT 100k 1M FREQUENCY - Hz 10M 100M VS = 15V
VS = 5V
100k
1M FREQUENCY - Hz
10M
100M
10k
Figure 13. Common-Mode Rejection vs. Frequency
Figure 14. Power Supply Rejection vs. Frequency
-40
-40
HARMONIC DISTORTION - dBc
VO = 2V p-p
HARMONIC DISTORTION - dBc
-60
RL = 100 GAIN = +2 2nd HARMONIC
-60
15V SUPPLIES GAIN = +2 RL = 400
VS = 5V
-80 VOUT = 20V p-p -100 2nd HARMONIC 3rd HARMONIC -120 2nd 3rd VOUT = 2V p-p
-80 3rd HARMONIC VS = 15V 2nd -120 100 3rd
-100
1k
10k 100k FREQUENCY - Hz
1M
10M
-140 100
1k
10k
100k
1M
10M
FREQUENCY - Hz
Figure 15. Harmonic Distortion vs. Frequency (RL = 100 )
Figure 16. Harmonic Distortion vs. Frequency (RL = 400 )
10 8
1200 RL = 400
OUTPUT SWING FROM V TO 0V
6 4 2 0 -2 -4 -6 -8 0.1% 0.01% 0.1%
0.01%
1000
SLEW RATE - V/s
800 GAIN = -10 GAIN = +10
RF = RG = 1k RL = 400
600
GAIN = +2 400
-10 0 20 40 60 80 100 120 140 SETTLING TIME - ns 160 180 200
200
2
4
6 8 10 12 14 SUPPLY VOLTAGE - Volts
16
18
Figure 17. Output Swing and Error vs. Settling Time
Figure 18. Slew Rate vs. Supply Voltage
-6-
REV. A
Typical Characteristics, Noninverting Connection-AD810
RF
100
1V
20nS
+VS
0.1F
VIN 90
RG 2
7
VO TO TEKTRONIX P6201 FET PROBE 6 VO RL
10 0%
AD810
VIN HP8130 PULSE GENERATOR 50 -VS 3 4 0.1F
VO
1V
Figure 19. Noninverting Amplifier Connection
Figure 20. Small Signal Pulse Response, Gain = +1, RF = 1 k, RL = 150 , VS = 15 V
0
PHASE SHIFT - Degrees
-45 -90
PHASE
PHASE 1
GAIN = +1 RL = 1k
-45 -90
CLOSED-LOOP GAIN - dB
1 VS = 15V 0 5V -1 -2 -3 -4 -5 1 10 100 FREQUENCY - MHz VS = 15V 5V 2.5V GAIN
-135 -180 -225
CLOSED-LOOP GAIN - dB
VS = 15V 5V 2.5V GAIN
-135 -180 -225 -270
0 -1 -2 -3 -4 -5 VS = 15V 5V 2.5V 1 10 100 FREQUENCY - MHz
2.5V -270
1000
1000
Figure 21. Closed-Loop Gain and Phase vs. Frequency, G= +1. RF = 1 k for 15 V, 910 for 5 V and 2.5 V
Figure 22. Closed-Loop Gain and Phase vs. Frequency, G= +1, RF = 1 k for 15 V, 910 for 5 V and 2.5 V
110 100 90 G = +1 RL = 150 VO = 250mV p-p RF = 750
200 180
PEAKING 1dB
160
G = +1 RL = 1k VO = 250mV p-p
-3dB BANDWIDTH - MHz
80 70 60 50 40 30 20 RF = 1.5k RF = 1k
-3dB BANDWIDTH - MHz
PEAKING 1dB
140 120 100 RF = 750 80 60 40 20 RF = 1.5k RF = 1k PEAKING 0.1dB
PEAKING 0.1 dB
2
4
6
8
10
12
14
16
18
2
4
6
8
10
12
14
16
18
SUPPLY VOLTAGE - Volts
SUPPLY VOLTAGE - Volts
Figure 23. Bandwidth vs. Supply Voltage, Gain = +1, RL = 150
Figure 24. -3 dB Bandwidth vs. Supply Voltage G = +1, RL = 1 k
REV. A
-7-
PHASE SHIFT - Degrees
GAIN = +1 RL = 150
0
AD810-Typical Characteristics, Noninverting Connection
100mV
100 90
20nS
100
1V
50nS
VIN
VIN 90
VO
10 0%
VO
10 0%
1V
10V
Figure 25. Small Signal Pulse Response, Gain = +10, RF = 442 , RL = 150 , VS = 15 V
Figure 26. Large Signal Pulse Response, Gain = +10, RF = 442 , RL = 400 , VS = 15 V
PHASE SHIFT - Degrees
PHASE
RL = 150
-45 -90
PHASE
RF = 270 RL = 1k
-45 -90 -135
CLOSED-LOOP GAIN - dB
CLOSED-LOOP GAIN - dB
21 20 19 GAIN 18 17 16 15 1 VS = 15V 5V 2.5V VS = 15V 5V 2.5V
-135 -180 -225 -270
21 20 19 GAIN 18 17 16 15 1 VS = 15V 5V 2.5V 10 100 FREQUENCY - MHz 5V 2.5V VS = 15V
-180 -225 -270
10 100 FREQUENCY - MHz
1000
1000
Figure 27. Closed-Loop Gain and Phase vs. Frequency, G = +10, RL = 150
Figure 28. Closed-Loop Gain and Phase vs. Frequency, G = +10, RL = 1 k
100
100
-3dB BANDWIDTH - MHz
G = +10 RL = 150 VO = 250mV p-p
G = +10 RL = 1k VO = 250m V p-p
-3dB BANDWIDTH - MHz
90 80 70 60 50 40 30 20
90 80 70 60 50 40 30
PEAKING 0.5dB RF = 232
PEAKING 0.5dB RF = 232 RF = 442 RF = 1k PEAKING 0.1dB
RF = 442
PEAKING 0.1dB
20
16 18
RF = 1k 2 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18
2
4
6 8 10 12 14 SUPPLY VOLTAGE - Volts
Figure 29. -3 dB Bandwidth vs. Supply Voltage, Gain = +10, RL = 150
Figure 30. -3 dB Bandwidth vs. Supply Voltage, Gain = +10, RL = 1 k
-8-
REV. A
PHASE SHIFT- Degrees
GAIN = +10 RF = 270
0
GAIN = +10
0
Typical Characteristics, Inverting Connection- AD810
1V
RF
100
20nS
+VS
VIN 90
0.1F VO TO TEKTRONIX P6201 FET PROBE 6 0.1F RL VO
RG VIN HP8130 PULSE GENERATOR 2
7
AD810
3 4
VO
10 0%
-VS
1V
Figure 31. Inverting Amplifier Connection
Figure 32. Small Signal Pulse Response, Gain = -1, RF = 681 , RL = 150 , VS = 5 V
PHASE
RL = 150
PHASE
90 1 45 VS = 15V 5V GAIN -2 -3 -4 -5 1 VS = 15V 5V 2.5V 2.5V -90 0 -45
RL = 1k
90 45
1
CLOSED-LOOP GAIN - dB
CLOSED-LOOP GAIN - dB
0 -1
0 -1 GAIN -2 -3 -4 -5 VS = 15V 5V 2.5V
VS = 15V 5V 2.5V
0 -45 -90
10 100 FREQUENCY - MHz
1000
1
10 100 FREQUENCY - MHz
1000
Figure 33. Closed-Loop Gain and Phase vs. Frequency G = -1, RL = 150 , RF = 681 for 15 V, 620 for 5 V and 2.5 V
Figure 34. Closed-Loop Gain and Phase vs. Frequency, G = -1, RL = 1 k, RF = 681 for VS = 15 V, 620 for 5 V and 2.5 V
100 90
G = -1 RL = 150 VO = 250mV p-p
180 G = -1 160 RL = 1k VO = 250mV p-p
-3dB BANDWIDTH - MHz
-3dB BANDWIDTH - MHz
80 70 60 50 40 30 RF = 1k 20 2 4 RF = 681 RF = 500
PEAKING 1.0dB
140 120 100 80 60 40 20
PEAKING 1.0dB RF = 500 PEAKING 0.1dB RF = 649 RF = 1k 2 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18
PEAKING 0.1dB
6 8 10 12 14 SUPPLY VOLTAGE - Volts
16
18
Figure 35. -3 dB Bandwidth vs. Supply Voltage, Gain = -1, RL = 150
Figure 36. -3 dB Bandwidth vs. Supply Voltage, Gain = -1, RL = 1 k
REV. A
-9-
PHASE SHIFT - Degrees
GAIN = -1
PHASE SHIFT - Degrees
180 135
180 GAIN = -1 135
AD810 -Typical Characteristics, Inverting Connection
100mV
100
20nS
100
1V
50nS
VIN
90
VIN
90
VO
10 0%
VO
10 0%
1V
10V
Figure 37. Small Signal Pulse Response, Gain = -10, RF = 442 , RL = 150 , VS = 15 V
Figure 38. Large Signal Pulse Response, Gain = -10, RF = 442 , RL = 400 , VS = 15 V
180 GAIN = -10 PHASE RF = 249 RL = 150 21
180
PHASE SHIFT - Degrees
135 90 45 0
PHASE
RF = 249 RL = 1k
135 90 45 0
CLOSED-LOOP GAIN - dB
CLOSED-LOOP GAIN - dB
21 20 19 GAIN 18 17 16 15 1 VS = 15V 5V 2.5V 10 100 FREQUENCY - MHz VS = 15V 5V 2.5V
20 19 GAIN 18 17 16 15 1 10 100 FREQUENCY - MHz VS = 15V 5V 2.5V VS = 15V 5V 2.5V
-45 -90
-45 -90
1000
1000
Figure 39. Closed-Loop Gain and Phase vs. Frequency, G = -10, RL = 150
Figure 40. Closed-Loop Gain and Phase vs. Frequency, G = -10, RL = 1 k
100
G = -10 RL = 150 VO = 250mV p- p
100 NO PEAKING G = -10 NO PEAKING
-3dB BANDWIDTH - MHz
-3dB BANDWIDTH - MHz
90 80 70 60 50 40 30 20
90 80 70 60 50 40 30
RL = 1k VO = 250mV p- p
RF = 249
RF = 249 RF = 442
RF = 442 RF = 750
RF = 750 2 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18
20 2 4
6 8 10 12 14 SUPPLY VOLTAGE - Volts
16
18
Figure 41. -3 dB Bandwidth vs. Supply Voltage, G = -10, RL = 150
Figure 42. -3 dB Bandwidth vs. Supply Voltage, G = -10, RL = 1 k
-10-
REV. A
PHASE SHIFT - Degrees
GAIN = -10
Applications- AD810
GENERAL DESIGN CONSIDERATIONS PRINTED CIRCUIT BOARD LAYOUT
The AD810 is a current feedback amplifier optimized for use in high performance video and data acquisition systems. Since it uses a current feedback architecture, its closed-loop bandwidth depends on the value of the feedback resistor. Table I below contains recommended resistor values for some useful closedloop gains and supply voltages. As you can see in the table, the closed-loop bandwidth is not a strong function of gain, as it would be for a voltage feedback amp. The recommended resistor values will result in maximum bandwidths with less than 0.1 dB of peaking in the gain vs. frequency response. The -3 dB bandwidth is also somewhat dependent on the power supply voltage. Lowering the supplies increases the values of internal capacitances, reducing the bandwidth. To compensate for this, smaller values of feedback resistor are sometimes used at lower supply voltages. The characteristic curves illustrate that bandwidths of over 100 MHz on 30 V total and over 50 MHz on 5 V total supplies can be achieved.
Table I. -3 dB Bandwidth vs. Closed-Loop Gain and Resistance Values (RL = 150 )
As with all wideband amplifiers, PC board parasitics can affect the overall closed-loop performance. Most important are stray capacitances at the output and inverting input nodes. (An added capacitance of 2 pF between the inverting input and ground will add about 0.2 dB of peaking in the gain of 2 response, and increase the bandwidth to 105 MHz.) A space (3/16" is plenty) should be left around the signal lines to minimize coupling. Also, signal lines connecting the feedback and gain resistors should be short enough so that their associated inductance does not cause high frequency gain errors. Line lengths less than 1/4" are recommended.
QUALITY OF COAX CABLE
Optimum flatness when driving a coax cable is possible only when the driven cable is terminated at each end with a resistor matching its characteristic impedance. If coax were ideal, then the resulting flatness would not be affected by the length of the cable. While outstanding results can be achieved using inexpensive cables, some variation in flatness due to varying cable lengths is to be expected.
POWER SUPPLY BYPASSING
VS = 15 V Closed-Loop Gain +1 +2 +10 -1 -10 VS = 5 V Closed-Loop Gain +1 +2 +10 -1 -10
RFB 1 k 715 270 681 249
RG 715 30 681 24.9
-3 dB BW (MHz) 80 75 65 70 65 -3 dB BW (MHz) 50 50 50 55 50
RFB 910 715 270 620 249
RG 715 30 620 24.9
Adequate power supply bypassing can be critical when optimizing the performance of a high frequency circuit. Inductance in the power supply leads can contribute to resonant circuits that produce peaking in the amplifier's response. In addition, if large current transients must be delivered to the load, then bypass capacitors (typically greater than 1 F) will be required to provide the best settling time and lowest distortion. Although the recommended 0.1 F power supply bypass capacitors will be sufficient in most applications, more elaborate bypassing (such as using two paralleled capacitors) may be required in some cases. The AD810 will operate with supplies from 18 V down to about 2.5 V. On 2.5 V the low distortion output voltage swing will be better than 1 V peak to peak. Single supply operation can be realized with excellent results by arranging for the input common-mode voltage to be biased at the supply midpoint.
OFFSET NULLING POWER SUPPLY OPERATING RANGE
ACHIEVING VERY FLAT GAIN RESPONSE AT HIGH FREQUENCY
Achieving and maintaining gain flatness of better than 0.1 dB above 10 MHz is not difficult if the recommended resistor values are used. The following issues should be considered to ensure consistently excellent results.
CHOICE OF FEEDBACK AND GAIN RESISTOR
Because the 3 dB bandwidth depends on the feedback resistor, the fine scale flatness will, to some extent, vary with feedback resistor tolerance. It is recommended that resistors with a 1% tolerance be used if it is desired to maintain exceptional flatness over a wide range of production lots.
A 10 k pot connected between Pins 1 and 5, with its wiper connected to V+, can be used to trim out the inverting input current (with about 20 A of range). For closed-loop gains above about 5, this may not be sufficient to trim the output offset voltage to zero. Tie the pot's wiper to ground through a large value resistor (50 k for 5 V supplies, 150 k for 15 V supplies) to trim the output to zero at high closed-loop gains.
REV. A
-11-
AD810
CAPACITIVE LOADS
LOAD CAPACITANCE - pF
When used with the appropriate feedback resistor, the AD810 can drive capacitive loads exceeding 1000 pF directly without oscillation. By using the curves in Figure 45 to chose the resistor value, less than 1 dB of peaking can easily be achieved without sacrificing much bandwidth. Note that the curves were generated for the case of a 10 k load resistor, for smaller load resistances, the peaking will be less than indicated by Figure 45. Another method of compensating for large load capacitances is to insert a resistor in series with the loop output as shown in Figure 43. In most cases, less than 50 is all that is needed to achieve an extremely flat gain response. Figures 44 to 46 illustrate the outstanding performance that can be achieved when driving a 1000 pF capacitor.
RF +VS 0.1F 1.0F RG 2 7 RS (OPTIONAL)
1000
VS = 5V
100
VS = 15V
10
GAIN = +2 RL = 1k
1 0 1k 2k 3k 4k FEEDBACK RESISTOR -
Figure 45. Max Load Capacitance for Less than 1 dB of Peaking vs. Feedback Resistor
5V 100nS
AD810
VIN RT -VS 3 4
6 1.0F 0.1F CL RL
VO
VIN 100
90
VOUT
Figure 43. Circuit Options for Driving a Large Capacitive Load
G = +2 VS = 15V RL= 10k CL = 1000pF
0%
5V
CLOSED-LOOP GAIN - dB
9 6 3 0 -3 -6 -9 RF = 4.5k RS = 0
Figure 46. AD810 Driving a 1000 pF Load, Gain = +2, RF = 750 , RS = 11 , RL = 10 k
DISABLE MODE
RF = 750 RS = 11
1
10 FREQUENCY - MHz
100
By pulling the voltage on Pin 8 to common (0 V), the AD810 can be put into a disabled state. In this condition, the supply current drops to less than 2.8 mA, the output becomes a high impedance, and there is a high level of isolation from input to output. In the case of a line driver for example, the output impedance will be about the same as for a 1.5 k resistor (the feedback plus gain resistors) in parallel with a 13 pF capacitor (due to the output) and the input to output isolation will be better than 65 dB at 1 MHz. Leaving the disable pin disconnected (floating) will leave the AD810 operational in the enabled state. In cases where the amplifier is driving a high impedance load, the input to output isolation will decrease significantly if the input signal is greater than about 1.2 V peak to peak. The isolation can be restored back to the 65 dB level by adding a dummy load (say 150 ) at the amplifier output. This will attenuate the feedthrough signal. (This is not an issue for multiplexer applications where the outputs of multiple AD810s are tied together as long as at least one channel is in the ON state.) The input impedance of the disable pin is about 35 k in parallel with a few pF. When grounded, about 50 A flows out
Figure 44. Performance Comparison of Two Methods for Driving a Large Capacitive Load
-12-
REV. A
AD810
DIFFERENTIAL GAIN - %
0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 5 6 7 8 9 10 11 12 13 14 SUPPLY VOLTAGE - Volts GAIN PHASE 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 15
When operated on 15 V supplies, the AD810 disable pin may be driven by open drain logic such as the 74C906. In this case, adding a 10 k pull-up resistor from the disable pin to the plus supply will decrease the enable time to about 150 ns. If there is a nonzero voltage present on the amplifier's output at the time it is switched to the disabled state, some additional decay time will be required for the output voltage to relax to zero. The total time for the output to go to zero will generally be about 250 ns and is somewhat dependent on the load impedance.
OPERATION AS A VIDEO LINE DRIVER
Figure 49. Differential Gain and Phase vs. Supply Voltage
+0.1 RL = 150 0 -0.1 5V 2.5 15V
715
715
NORMALIZED GAIN - dB
The AD810 is designed to offer outstanding performance at closed-loop gains of one or greater. At a gain of 2, the AD810 makes an excellent video line driver. The low differential gain and phase errors and wide -0.1 dB bandwidth are nearly independent of supply voltage and load (as seen in Figures 49 and 50).
+0.1 RL= 1k 0 15V -0.1 5V
+VS
0.1F
7 2 75 CABLE VIN 3 75
75 CABLE VOUT 75
AD810
4 0.1F
6
2.5 1M 10M FREQUENCY - Hz 100M
100k
75
-VS
Figure 50. Fine-Scale Gain (Normalized) vs. Frequency for Various Supply Voltages, Gain = +2, RF = 715
110
Figure 47. A Video Line Driver Operating at a Gain of +2
0
100 G = +2 RL = 150 VO = 250mV p-p RF = 500 PEAKING 1.0dB
PHASE SHIFT - Degrees
-3dB BANDWIDTH - MHz
PHASE
GAIN = +2 RL = 150
-45 -90
90 80 70 60
CLOSED-LOOP GAIN - dB
1 0 GAIN -1 2.5V -2 -3 -4 -5 1 10 100 FREQUENCY - MHz VS = 15V 5V 2.5V VS = 15V
-135 -180 5V -225 -270
RF = 750 50 40 RF = 1k 30 20 2 4 6 8 10 12
PEAKING 0.1dB
1000
14
16
18
SUPPLY VOLTAGE - Volts
Figure 48. Closed-Loop Gain and Phase vs. Frequency, G = +2, RL = 150, RF = 715
Figure 51. -3 dB Bandwidth vs. Supply Voltage, Gain = +2, RL = 150
REV. A
-13-
DIFFERENTIAL PHASE - Degrees
of the disable the disable pin for 5 V supplies. If driven by complementary output CMOS logic (such as the 74HC04), the disable time (until the output goes high impedance) is about 100 ns and the enable time (to low impedance output) is about 170 ns on 5 V supplies. The enable time can be extended to about 750 ns by using open drain logic such as the 74HC05.
0.10 0.09 GAIN = +2 RF = 715 RL = 150 fC = 3.58MHz 100 IRE MODULATED RAMP
0.20 0.18
AD810
2:1 VIDEO MULTIPLEXER
750 +5V 0.1F 2 VINA 3 75 7 750
The outputs of two AD810s can be wired together to form a 2:1 mux without degrading the flatness of the gain response. Figure 54 shows a recommended configuration which results in -0.1 dB bandwidth of 20 MHz and OFF channel isolation of 77 dB at 10 MHz on 5 V supplies. The time to switch between channels is about 0.75 s when the disable pins are driven by open drain output logic. Adding pull-up resistors to the logic outputs or using complementary output logic (such as the 74HC04) reduces the switching time to about 180 ns. The switching time is only slightly affected by the signal level.
500mV
100 90
AD810
4 8 -5V
6 0.1F
75
75 CABLE VOUT 75
750 +5V
750 0.1F
500nS
VINB
2
7
AD810
3 4 8 -5V
6 0.1F
75
VSW
10 0%
74HC04
5V
Figure 54. A Fast Switching 2:1 Video Mux
Figure 52. Channel Switching Time for the 2:1 Mux
-45
-50
0.5
-90 -135 -180 GAIN -225 -270 VS = 5V
CLOSED-LOOP GAIN - dB
FEEDTHROUGH - dB
0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 1 10 FREQUENCY - MHz
-60
-70
-80
100
-90 1 10 FREQUENCY - MHz 100
Figure 53. 2:1 Mux OFF Channel Feedthrough vs. Frequency
Figure 55. 2:1 Mux ON Channel Gain and Phase vs. Frequency
-14-
REV. A
PHASE SHIFT - Degrees
-40
PHASE
0
AD810
N:1 MULTIPLEXER
1k +VS 0.1F 2 VIN, A 75 7 33
A multiplexer of arbitrary size can be formed by combining the desired number of AD810s together with the appropriate selection logic. The schematic in Figure 58 shows a recommendation for a 4:1 mux which may be useful for driving a high impedance such as the input to a video A/D converter (such as the AD773). The output series resistors effectively compensate for the combined output capacitance of the OFF channels plus the input capacitance of the A/D while maintaining wide bandwidth. In the case illustrated, the -0.1 dB bandwidth is about 20 MHz with no peaking. Switching time and OFF channel isolation (for the 4:1 mux) are about 250 ns and 60 dB at 10 MHz, respectively.
PHASE SHIFT - Degrees
0 PHASE -45 0.5 -90 -135 -180 GAIN -1.0 -1.5 -2.0 -2.5 VS = 15V RL = 10k CL = 10pF -225
AD810
3 0.1F -VS 1k +VS 8 4
6
SELECT A
0.1F 2 VIN, B 3 75 0.1F -VS 1k +VS 0.1F 2 VIN, C 7 33 RL CL 7 33
AD810
8 4
6
SELECT B VOUT
CLOSED-LOOP GAIN - dB
0 -0.5
AD810
3 8 4
6
-3.0 1 10 FREQUENCY - MHz 100
75
0.1F -VS +VS 0.1F 1k
SELECT C
Figure 56. 4:1 Mux ON Channel Gain and Phase vs. Frequency
-30
2
7
FEEDTHROUGH - dB
-40
VIN, D 3 75 0.1F
AD810
8 4
33 6
SELECT D -VS
-50
-60
Figure 58. A 4:1 Multiplexer Driving a High Impedance
-70 1 10 FREQUENCY - MHz 100
Figure 57. 4:1 Mux OFF Channel Feedthrough vs. Frequency
REV. A
-15-
AD810
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Plastic Mini-DIP (N) Package
8 PIN 1 1 4 0.30 (7.62) REF 0.035 0.01 (0.89 0.25) 5 0.31 (7.87)
0.39 (9.91) MAX
0.165 0.01 (4.19 0.25) 0.125 (3.18) MIN 0.018 0.003 (0.46 0.08) 0.10 (2.54) BSC 0.033 (0.84) NOM
0.18 0.03 (4.57 0.76)
0.011 0.003 (0.28 0.08) 15 0
SEATING PLANE
Cerdip (Q) Package
0.005 (0.13) MIN 0.055 (1.40) MAX
8 PIN 1 1
5 0.310 (7.87) 0.220 (5.59) 4 0.320 (8.13) 0.290 (7.37) 0.060 (1.52) 0.015 (0.38)
0.405 (10.29) MAX 0.200 (5.08) MAX 0.200 (5.08) 0.125 (3.18) 0.023 (0.58) 0.100 0.070 (1.78) 0.014 (0.36) (2.54) 0.030 (0.76) BSC
0.150 (3.81) MIN
0.015 (0.38) 0.008 (0.20) 15 0
SEATING PLANE
8-Pin SOIC (R) Package
0.150 (3.81)
8 0.244 (6.20) 0.228 (5.79) PIN 1 1
5 0.157 (3.99) 0.150 (3.81) 4
0.197 (5.01) 0.189 (4.80) 0.010 (0.25) 0.004 (0.10) 0.050 (1.27) BSC 0.102 (2.59) 0.094 (2.39) 0.019 (0.48) 0.014 (0.36)
0.020 (0.051) x 45 CHAMF 0.190 (4.82) 0.170 (4.32) 8 0 10 0
0.090 (2.29)
0.098 (0.2482) 0.075 (0.1905)
0.030 (0.76) 0.018 (0.46)
All brand or product names mentioned are trademarks or registered trademarks of their respective holders.
-16-
REV. A
PRINTED IN U.S.A.
C1737-24-10/92
0.25 (6.35)

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