a Low Power Video Op Amp with Disable AD810 FEATURES High Speed 80 MHz Bandwidth (3 dB, G = +1) 75 MHz Bandwidth (3 dB, G = +2) 1000 V/ms 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 0.048 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 65 V and 615 V Operation 62.9 V Output Swing Into a 150 V Load (VS = 65 V) APPLICATIONS Professional Video Cameras Multimedia Systems NTSC, PAL & SECAM Compatible Systems Video Line Driver ADC/DAC Buffer DC Restoration Circuits CONNECTION DIAGRAM 8-Pin Plastic Mini-DIP (N), SOIC (R) and Cerdip (Q) Packages OFFSET NULL 1 8 DISABLE -IN 2 7 +V S +IN 3 6 OUTPUT -VS 4 5 OFFSET NULL AD810 TOP VIEW 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. 0.20 -45 -90 CLOSED-LOOP GAIN - dB 1 -135 VS = 15V 0 -180 GAIN 5V -225 -1 2.5V -270 -2 DIFFERENTIAL GAIN - % PHASE PHASE SHIFT - Degrees GAIN = +2 RL = 150 0.09 GAIN = +2 RF = 715 RL = 150 fC = 3.58MHz 100 IRE MODULATED RAMP 0.08 0.07 0.14 0.10 0.05 GAIN 0.04 0.08 PHASE 0.03 0.06 0.02 0.04 0.01 0.02 5V -4 0.16 0.12 0.06 VS = 15V -3 0.18 DIFFERENTIAL PHASE - Degrees 0.10 0 2.5V -5 0 1 10 100 FREQUENCY - MHz 1000 Closed-Loop Gain and Phase vs. Frequency, G = +2, RL = 150, RF = 715 5 6 7 8 9 10 11 12 13 14 0 15 SUPPLY VOLTAGE - Volts 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 AD810-SPECIFICATIONS (@ T = +258C and V = 615 V dc, R = 150 V unless otherwise noted) A Parameter DYNAMIC PERFORMANCE 3 dB Bandwidth 0.1 dB Bandwidth Full Power Bandwidth S L Conditions VS Min (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 5 V 15 V 15 V 15 V 5 V 15 V 40 55 40 50 13 15 AD810A Typ Max 50 75 80 65 22 30 Min 40 55 40 50 13 15 AD810S1 Typ Max Units 50 75 80 65 22 30 MHz MHz MHz MHz MHz MHz 16 350 1000 50 125 0.02 0.04 0.04 0.045 MHz V/s V/s ns ns % % Degrees Degrees 15 V 5 V 15 V 15 V 15 V 15 V 5 V 15 V 5 V 16 350 1000 50 125 0.02 0.04 0.04 0.045 15 V -61 TMIN-TMAX 5 V, 15 V 5 V, 15 V 1.5 2 7 6 7.5 1.5 4 15 6 15 mV mV V/C TMIN-TMAX TMIN-TMAX 5 V, 15 V 5 V, 15 V 0.7 2 5 7.5 0.8 2 5 10 A A OPEN-LOOP TRANSRESISTANCE TMIN-TMAX VO = 10 V, RL = 400 VO = 2.5 V, RL = 100 15 V 5 V 1.0 0.3 3.5 1.2 1.0 0.2 3.5 1.0 M M OPEN-LOOP DC VOLTAGE GAIN TMIN-TMAX VO = 10 V, RL = 400 VO = 2.5 V, RL = 100 15 V 5 V 86 76 100 88 80 72 100 88 dB dB COMMON-MODE REJECTION VOS TMIN-TMAX VCM = 12 V VCM = 2.5 V TMIN-TMAX 15 V 5 V 5 V, 15 V 56 52 64 60 0.1 56 50 0.4 64 60 0.1 0.4 dB dB A/V 72 0.05 0.3 72 0.05 0.3 dB A/V 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 Input Current 0.05 0.07 0.07 0.08 0.05 0.07 0.07 0.08 -61 dBc 4.5 V to 18 V POWER SUPPLY REJECTION VOS Input Current TMIN-TMAX TMIN-TMAX INPUT VOLTAGE NOISE f = 1 kHz 5 V, 15 V 2.9 2.9 nV/Hz INPUT CURRENT NOISE -IIN, f = 1 kHz +IIN, f = 1 kHz 5 V, 15 V 5 V, 15 V 13 1.5 13 1.5 pA/Hz pA/Hz INPUT COMMON-MODE VOLTAGE RANGE OUTPUT CHARACTERISTICS Output Voltage Swing3 Short-Circuit Current Output Current OUTPUT RESISTANCE INPUT CHARACTERISTICS Input Resistance Input Capacitance DISABLE CHARACTERISTICS4 OFF Isolation OFF Output Impedance RL = 150 , TMIN-TMAX RL = 400 RL = 400 , TMIN-TMAX TMIN-TMAX 65 5 V 15 V 2.5 12 3.0 13 2.5 12 3 13 V V 5 V 15 V 15 V 15 V 5 V, 15 V 2.5 12.5 12 2.9 12.9 2.5 12.5 12 2.9 12.9 150 60 V V V mA mA 15 10 40 2 M pF 64 (RF+ RG)i13 pF dB 40 Open Loop (5 MHz) +Input -Input +Input 60 150 60 30 15 15 V 15 V 15 V f = 5 MHz, See Figure 43 See Figure 43 2.5 10 40 2 64 (RF + RG)i13 pF -2- 2.5 REV. A AD810 Parameter Conditions 5 VS Turn On Time Turn Off Time Disable Pin Current ZOUT = Low, See Figure 54 ZOUT = High Disable Pin = 0 V Min Disable Pin Current to Disable TMIN-TMAX POWER SUPPLY Operating Range +25C to TMAX TMIN 5 V 15 V 170 100 50 290 5 V, 15 V 30 2.5 3.0 5 V 15 V 5 V, 15 V 5 V 15 V Quiescent Current TMIN-TMAX Power-Down Current AD810A Typ Max Min 6.7 6.8 8.3 1.8 2.1 Min AD810S1 Typ Max 170 100 50 290 75 400 75 400 2.5 3.5 6.7 6.8 9 1.8 2.1 ns ns A A A 30 18 18 7.5 8.0 10.0 2.3 2.8 Units 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. 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 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 TOTAL POWER DISSIPATION - Watts ABSOLUTE MAXIMUM RATINGS 1 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. 8-PIN MINI-DIP 2.0 1.8 1.6 1.4 1.2 8-PIN CERDIP 0.8 0.6 0.4 -60 8-PIN SOIC -40 -20 0 20 40 60 80 100 120 140 AMBIENT TEMPERATURE - C ESD SUSCEPTIBILITY 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. 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. SEE TEXT +VS 0.1F 10k 7 2 ORDERING GUIDE 1 AD810 Model Temperature Range Package Description Package Option AD810AN AD810AR AD810AR-REEL 5962-9313201MPA -40C to +85C -40C to +85C -40C to +85C -55C to +125C 8-Pin Plastic DIP 8-Pin Plastic SOIC 8-Pin Plastic SOIC 8-Pin Cerdip N-8 R-8 R-8 Q-8 REV. A 8-PIN MINI-DIP 1.0 3 4 5 6 0.1F -VS Offset Null Configuration -3- 20 MAGNITUDE OF THE OUTPUT VOLTAGE - Volts MAGNITUDE OF THE OUTPUT VOLTAGE - Volts AD810 -Typical Characteristics 20 15 NO LOAD 10 RL = 150 5 15 NO LOAD 10 RL = 150 5 0 0 0 5 10 15 SUPPLY VOLTAGE - Volts 0 20 Figure 1. Input Common-Mode Voltage Range vs. Supply Voltage 20 10 30 9 15V SUPPLY SUPPLY CURRENT - mA OUTPUT VOLTAGE - Volts p-p 10 15 SUPPLY VOLTAGE - Volts Figure 2. Output Voltage Swing vs. Supply 35 25 20 15 10 VS = 15V 8 VS = 5V 7 6 5V SUPPLY 5 5 0 10 100 1k LOAD RESISTANCE - Ohms 4 -60 10k -20 0 20 40 60 80 100 120 140 Figure 4. Supply Current vs. Junction Temperature 10 10 8 INPUT OFFSET VOLTAGE - mV 8 6 NONINVERTING INPUT 4 VS = 5V, 15V 2 0 -2 INVERTING INPUT VS = 5V, 15V -4 -6 6 4 VS = 5V 2 0 VS = 15V -2 -4 -6 -8 -8 -10 -60 -40 JUNCTION TEMPERATURE - C Figure 3. Output Voltage Swing vs. Load Resistance INPUT BIAS CURRENT - A 5 -40 -20 0 20 40 60 80 100 120 -10 -60 140 -40 -20 0 20 40 60 80 100 120 140 JUNCTION TEMPERATURE - C JUNCTION TEMPERATURE - C Figure 6. Input Offset Voltage vs. Junction Temperature Figure 5. Input Bias Current vs. Temperature -4- REV. A Typical Characteristics- AD810 120 100 200 VS = 15V OUTPUT CURRENT - mA SHORT CIRCUIT CURRENT - mA 250 VS = 15V 150 100 80 60 VS = 5V 40 VS = 5V 50 -60 -40 -20 0 +20 +40 +60 +80 +100 +120 20 -60 +140 -40 -20 +20 +40 +60 +80 +100 +120 +140 Figure 8. Linear Output Current vs. Temperature Figure 7. Short Circuit Current vs. Temperature 1M 10.0 GAIN = 2 VS = 5V OUTPUT RESISTANCE - CLOSED-LOOP OUTPUT RESISTANCE - 0 JUNCTION TEMPERATURE - C JUNCTION TEMPERATURE - C RF = 715 1.0 VS = 15V 0.1 0.01 10k 100k 1M FREQUENCY - Hz 10M 100k 10k 1k 100 100k 100M 1M 10M 100M FREQUENCY - Hz Figure 10. Output Resistance vs. Frequency, Disabled State Figure 9. Closed-Loop Output Resistance vs. Frequency 100 100 30 VS = 15V VS = 5V TO 15V 20 OUTPUT LEVEL FOR 3% THD RL = 400 15 10 VS = 5V INVERTING INPUT CURRENT NOISE 10 10 VOLTAGE NOISE NONINVERTING INPUT CURRENT NOISE 5 0 100k 1M 10M FREQUENCY - Hz 1 10 100M 100 1k FREQUENCY - Hz 10k 1 100k Figure 12. Input Voltage and Current Noise vs. Frequency Figure 11. Large Signal Frequency Response REV. A CURRENT NOISE - pA/ Hz VOLTAGE NOISE - nV/ Hz OUTPUT VOLTAGE - Volts p-p 25 -5- AD810 -Typical Characteristics 90 70 POWER SUPPLY REJECTION - dB 80 COMMON-MODE REJECTION - dB 100 80 70 60 50 40 RF = 715 AV = +2 60 VS = 15V 50 VS = 5V 40 30 CURVES ARE FOR WORST CASE CONDITION WHERE ONE SUPPLY IS VARIED WHILE THE OTHER IS HELD CONSTANT 20 10 30 20 10k 100k 1M FREQUENCY - Hz 10M 100M 10k Figure 13. Common-Mode Rejection vs. Frequency 100k 1M FREQUENCY - Hz 10M 100M Figure 14. Power Supply Rejection vs. Frequency -40 -40 -60 HARMONIC DISTORTION - dBc HARMONIC DISTORTION - dBc VO = 2V p-p RL = 100 GAIN = +2 VS = 5V 2nd HARMONIC -80 3rd HARMONIC VS = 15V -100 2nd -120 RL = 400 -80 VOUT = 20V p-p -100 2nd HARMONIC 3rd HARMONIC VOUT = 2V p-p -120 2nd 3rd 100 15V SUPPLIES GAIN = +2 -60 3rd 1k 10k 100k FREQUENCY - Hz 1M -140 100 10M 1k 10k 100k 1M 10M FREQUENCY - Hz Figure 15. Harmonic Distortion vs. Frequency (RL = 100 ) Figure 16. Harmonic Distortion vs. Frequency (RL = 400 ) 1200 10 6 1000 0.01% 4 0.1% SLEW RATE - V/s OUTPUT SWING FROM V TO 0V 8 2 RF = RG = 1k 0 RL = 400 -2 -4 0.1% 0.01% RL = 400 800 GAIN = -10 GAIN = +10 600 GAIN = +2 400 -6 -8 -10 0 200 20 40 60 80 100 120 140 SETTLING TIME - ns 160 180 200 Figure 17. Output Swing and Error vs. Settling Time 2 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18 Figure 18. Slew Rate vs. Supply Voltage -6- REV. A Typical Characteristics, Noninverting Connection-AD810 1V RF 20nS 100 +VS RG VIN 90 0.1F VO TO TEKTRONIX P6201 FET PROBE 7 2 3 VO RL 0.1F 10 50 0% -VS 1V Figure 19. Noninverting Amplifier Connection Figure 20. Small Signal Pulse Response, Gain = +1, RF = 1 k, RL = 150 , VS = 15 V 0 -45 CLOSED-LOOP GAIN - dB -90 1 -135 VS = 15V 0 -180 5V -1 -225 GAIN 2.5V -270 -2 -3 VS = 15V -4 5V 2.5V 10 100 FREQUENCY - MHz 1 VS = 15V -135 5V -180 -1 -270 VS = 15V -3 5V -4 2.5V 10 100 FREQUENCY - MHz 1000 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 200 G = +1 RL = 150 VO = 250mV p-p 180 PEAKING 1dB 160 -3dB BANDWIDTH - MHz -3dB BANDWIDTH - MHz -225 GAIN 1 80 RF = 750 70 60 PEAKING 0.1 dB 50 RF = 1k 40 G = +1 RL = 1k VO = 250mV p-p PEAKING 1dB 140 120 100 PEAKING 0.1dB RF = 750 80 60 RF = 1k 40 30 RF = 1.5k 20 RF = 1.5k 20 2 4 6 8 10 12 14 16 18 2 SUPPLY VOLTAGE - Volts 4 6 8 10 12 14 16 18 SUPPLY VOLTAGE - Volts Figure 23. Bandwidth vs. Supply Voltage, Gain = +1, RL = 150 REV. A 2.5V -2 110 90 -90 0 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 100 -45 -5 -5 1 GAIN = +1 RL = 1k PHASE CLOSED-LOOP GAIN - dB PHASE 0 PHASE SHIFT - Degrees GAIN = +1 RL = 150 PHASE SHIFT - Degrees HP8130 PULSE GENERATOR 4 VO 6 AD810 VIN Figure 24. -3 dB Bandwidth vs. Supply Voltage G = +1, RL = 1 k -7- AD810-Typical Characteristics, Noninverting Connection 100mV 100 90 100 VIN 90 VO VO 10 10 0% 0% 10V 1V Figure 26. Large Signal Pulse Response, Gain = +10, RF = 442 , RL = 400 , VS = 15 V Figure 25. Small Signal Pulse Response, Gain = +10, RF = 442 , RL = 150 , VS = 15 V GAIN = +10 RF = 270 0 21 -135 20 -180 VS = 15V 19 18 -225 5V GAIN VS = 15V 17 5V 16 2.5V PHASE -270 2.5V 10 100 FREQUENCY - MHz 5V 16 2.5V -3dB BANDWIDTH - MHz -3dB BANDWIDTH - MHz VS = 15V 17 1 RL = 150 VO = 250mV p-p 70 PEAKING 0.5dB RF = 232 40 RF = 442 -270 2.5V 1000 10 100 FREQUENCY - MHz Figure 28. Closed-Loop Gain and Phase vs. Frequency, G = +10, RL = 1 k G = +10 50 -225 5V 18 100 60 -180 VS = 15V GAIN 100 80 -90 19 1000 Figure 27. Closed-Loop Gain and Phase vs. Frequency, G = +10, RL = 150 90 -45 -135 20 15 1 RF = 270 RL = 1k 21 CLOSED-LOOP GAIN - dB CLOSED-LOOP GAIN - dB -90 0 GAIN = +10 PHASE SHIFT - Degrees -45 RL = 150 PHASE 15 50nS 1V PHASE SHIFT- Degrees VIN 20nS PEAKING 0.1dB 90 G = +10 RL = 1k VO = 250m V p-p 80 PEAKING 0.5dB 70 RF = 232 60 50 40 RF = 442 PEAKING 0.1dB 30 30 RF = 1k 20 2 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 20 16 18 RF = 1k 2 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18 Figure 30. -3 dB Bandwidth vs. Supply Voltage, Gain = +10, RL = 1 k Figure 29. -3 dB Bandwidth vs. Supply Voltage, Gain = +10, RL = 150 -8- REV. A Typical Characteristics, Inverting Connection- AD810 1V 20nS RF 100 +VS RG VIN 90 0.1F VO TO TEKTRONIX P6201 FET PROBE 7 2 VIN HP8130 PULSE GENERATOR 3 4 VO VO 6 AD810 RL 0.1F 10 0% 1V -VS Figure 31. Inverting Amplifier Connection Figure 32. Small Signal Pulse Response, Gain = -1, RF = 681 , RL = 150 , VS = 5 V 45 CLOSED-LOOP GAIN - dB 0 -1 GAIN -2 0 -45 -90 VS = 15V 5V -4 2.5V 10 100 FREQUENCY - MHz -3dB BANDWIDTH - MHz 90 GAIN VS = 15V -3 5V -4 2.5V 180 VO = 250mV p-p 160 PEAKING 1.0dB RF = 500 60 RF = 681 PEAKING 0.1dB 40 30 140 RL = 1k VO = 250mV p-p 120 PEAKING 1.0dB 100 RF = 500 80 PEAKING 0.1dB 60 RF = 649 40 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 2 18 Figure 35. -3 dB Bandwidth vs. Supply Voltage, Gain = -1, RL = 150 REV. A RF = 1k 20 4 1000 10 100 FREQUENCY - MHz RF = 1k 20 2 -90 G = -1 80 50 1 -45 2.5V -2 G = -1 RL = 150 70 0 VS = 15V 5V 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 -3dB BANDWIDTH - MHz 100 0 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 45 -1 -5 1 90 1 2.5V -3 -5 VS = 15V 5V 135 RL = 1k PHASE SHIFT - Degrees 90 1 GAIN = -1 PHASE CLOSED-LOOP GAIN - dB 135 RL = 150 PHASE 180 PHASE SHIFT - Degrees 180 GAIN = -1 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18 Figure 36. -3 dB Bandwidth vs. Supply Voltage, Gain = -1, RL = 1 k -9- AD810 -Typical Characteristics, Inverting Connection 100mV 1V 20nS 100 100 VIN 50nS VIN 90 90 VO VO 10 10 0% 0% 10V 1V Figure 38. Large Signal Pulse Response, Gain = -10, RF = 442 , RL = 400 , VS = 15 V Figure 37. Small Signal Pulse Response, Gain = -10, RF = 442 , RL = 150 , VS = 15 V 90 RL = 150 CLOSED-LOOP GAIN - dB 135 21 45 20 0 VS = 15V 19 5V GAIN 18 17 5V 2.5V 16 1 10 100 FREQUENCY - MHz 80 0 5V GAIN 2.5V 18 5V 16 2.5V 1 10 100 FREQUENCY - MHz G = -10 70 60 RF = 249 RF = 442 40 30 90 RF = 750 4 1000 80 NO PEAKING RL = 1k VO = 250mV p- p 70 60 RF = 249 50 40 RF = 442 30 2 -90 VS = 15V 17 NO PEAKING RL = 150 VO = 250mV p- p 20 -45 100 G = -10 50 VS = 15V 19 Figure 40. Closed-Loop Gain and Phase vs. Frequency, G = -10, RL = 1 k -3dB BANDWIDTH - MHz -3dB BANDWIDTH - MHz 90 45 20 1000 Figure 39. Closed-Loop Gain and Phase vs. Frequency, G = -10, RL = 150 100 21 15 15 135 90 RL = 1k -90 2.5V VS = 15V -45 RF = 249 PHASE CLOSED-LOOP GAIN - dB RF = 249 PHASE SHIFT - Degrees PHASE GAIN = -10 PHASE SHIFT - Degrees 180 180 GAIN = -10 6 8 10 12 14 SUPPLY VOLTAGE - Volts RF = 750 20 16 2 18 Figure 41. -3 dB Bandwidth vs. Supply Voltage, G = -10, RL = 150 4 6 8 10 12 14 SUPPLY VOLTAGE - Volts 16 18 Figure 42. -3 dB Bandwidth vs. Supply Voltage, G = -10, R L = 1 k -10- REV. A 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. 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. 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 V) VS = 615 V Closed-Loop Gain RFB RG -3 dB BW (MHz) +1 +2 +10 -1 -10 1 k 715 270 681 249 715 30 681 24.9 80 75 65 70 65 VS = 65 V Closed-Loop Gain RFB RG -3 dB BW (MHz) +1 +2 +10 -1 -10 910 715 270 620 249 715 30 620 24.9 50 50 50 55 50 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 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. REV. A QUALITY OF COAX CABLE 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. POWER SUPPLY OPERATING RANGE 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 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. -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. VS = 5V 100 VS = 15V GAIN = +2 RL = 1k 10 1 Figures 44 to 46 illustrate the outstanding performance that can be achieved when driving a 1000 pF capacitor. 1k 0 2k 3k 4k FEEDBACK RESISTOR - RF Figure 45. Max Load Capacitance for Less than 1 dB of Peaking vs. Feedback Resistor 0.1F +VS 1000 1.0F RG 5V 7 2 RS (OPTIONAL) 6 AD810 3 VIN 4 RT 1.0F VIN 100 VO CL 100nS 90 RL 0.1F -VS VOUT Figure 43. Circuit Options for Driving a Large Capacitive Load 0% CLOSED-LOOP GAIN - dB 5V G = +2 VS = 15V RL= 10k CL = 1000pF 9 6 Figure 46. AD810 Driving a 1000 pF Load, Gain = +2, RF = 750 , RS = 11 , RL = 10 k 3 0 RF = 4.5k RS = 0 -3 DISABLE MODE RF = 750 RS = 11 -6 -9 1 10 FREQUENCY - MHz 100 Figure 44. Performance Comparison of Two Methods for Driving a Large Capacitive Load 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 -12- REV. A AD810 DIFFERENTIAL GAIN - % 0.09 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. 75 3 VIN 4 75 0.12 0.10 0.05 GAIN 0.04 0.08 PHASE 0.03 0.06 0.02 0.04 0.01 0.02 6 7 8 9 10 11 12 13 0 15 14 +0.1 RL = 150 15V NORMALIZED GAIN - dB 0 -0.1 5V 2.5 +0.1 RL= 1k 0 15V -0.1 75 CABLE 5V VOUT 6 AD810 0.14 SUPPLY VOLTAGE - Volts 0.1F 2 75 CABLE 0.06 5 715 7 0.07 0.16 0 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). +VS 0.18 GAIN = +2 RF = 715 RL = 150 fC = 3.58MHz 100 IRE MODULATED RAMP 0.08 Figure 49. Differential Gain and Phase vs. Supply Voltage OPERATION AS A VIDEO LINE DRIVER 715 0.20 0.10 2.5 75 0.1F 1M 100k -VS 10M FREQUENCY - Hz 100M Figure 50. Fine-Scale Gain (Normalized) vs. Frequency for Various Supply Voltages, Gain = +2, RF = 715 Figure 47. A Video Line Driver Operating at a Gain of +2 110 100 CLOSED-LOOP GAIN - dB -90 1 -135 VS = 15V 0 -180 GAIN 5V -225 -1 90 -3dB BANDWIDTH - MHz -45 PHASE SHIFT - Degrees 0 GAIN = +2 RL = 150 PHASE 2.5V -270 -2 VS = 15V -3 G = +2 PEAKING 1.0dB RL = 150 VO = 250mV p-p RF = 500 80 70 60 PEAKING 0.1dB RF = 750 50 40 RF = 1k 30 5V -4 20 2.5V -5 1 10 100 FREQUENCY - MHz 2 1000 4 6 8 10 12 14 16 18 SUPPLY VOLTAGE - Volts Figure 48. Closed-Loop Gain and Phase vs. Frequency, G = +2, RL = 150, RF = 715 REV. A 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. Figure 51. -3 dB Bandwidth vs. Supply Voltage, Gain = +2, RL = 150 -13- AD810 2:1 VIDEO MULTIPLEXER 500mV 750 750 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. +5V 0.1F 2 7 AD810 VINA 3 6 0.1F 4 8 75 75 75 CABLE VOUT -5V 75 750 750 +5V 2 500nS 7 AD810 VINB 100 0.1F 3 90 75 4 6 0.1F 8 -5V VSW 10 74HC04 0% 5V Figure 54. A Fast Switching 2:1 Video Mux Figure 52. Channel Switching Time for the 2:1 Mux 0 -45 CLOSED-LOOP GAIN - dB FEEDTHROUGH - dB -90 0.5 -50 -60 -70 -80 0 -135 -180 -0.5 GAIN -225 -1.0 PHASE SHIFT - Degrees PHASE -40 -270 -1.5 VS = 5V -2.0 -2.5 -3.0 1 10 FREQUENCY - MHz 100 -90 1 10 FREQUENCY - MHz 100 Figure 55. 2:1 Mux ON Channel Gain and Phase vs. Frequency Figure 53. 2:1 Mux OFF Channel Feedthrough vs. Frequency -14- REV. A AD810 N:1 MULTIPLEXER 1k 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 -45 CLOSED-LOOP GAIN - dB 0.5 -90 0 -135 -180 -0.5 GAIN -1.0 RL = 10k -2.0 CL = 10pF 2 VIN, A 75 3 33 6 8 4 SELECT A 0.1F -VS 1k +VS 0.1F 3 75 7 33 AD810 VIN, B 6 8 4 SELECT B 0.1F -VS VOUT 1k +VS RL 0.1F 2 -2.5 3 -3.0 10 FREQUENCY - MHz 100 75 CL 7 33 AD810 VIN, C 1 7 AD810 -225 VS = 15V -1.5 0.1F 2 PHASE SHIFT - Degrees 0 +VS 6 8 4 SELECT C 0.1F -VS Figure 56. 4:1 Mux ON Channel Gain and Phase vs. Frequency 1k +VS 0.1F -30 FEEDTHROUGH - dB 2 3 75 6 8 4 SELECT D 0.1F -50 -VS Figure 58. A 4:1 Multiplexer Driving a High Impedance -60 -70 1 10 FREQUENCY - MHz 100 Figure 57. 4:1 Mux OFF Channel Feedthrough vs. Frequency REV. A 33 AD810 VIN, D -40 7 -15- AD810 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). Plastic Mini-DIP (N) Package 8 0.25 (6.35) PIN 1 1 C1737-24-10/92 5 0.31 (7.87) 4 0.30 (7.62) REF 0.39 (9.91) MAX 0.035 0.01 (0.89 0.25) 0.165 0.01 (4.19 0.25) 0.011 0.003 (0.28 0.08) 0.18 0.03 (4.57 0.76) 0.125 (3.18) MIN 0.018 0.003 (0.46 0.08) 0.10 (2.54) BSC 0.033 (0.84) NOM 15 0 SEATING PLANE Cerdip (Q) Package 0.055 (1.40) MAX 0.005 (0.13) MIN 8 5 0.310 (7.87) 0.220 (5.59) PIN 1 1 4 0.320 (8.13) 0.290 (7.37) 0.405 (10.29) MAX 0.060 (1.52) 0.015 (0.38) 0.200 (5.08) MAX 0.150 (3.81) MIN 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 0.015 (0.38) 0.008 (0.20) 15 0 SEATING PLANE 8-Pin SOIC (R) Package 0.150 (3.81) 8 5 0.244 (6.20) 0.228 (5.79) 4 1 0.197 (5.01) 0.189 (4.80) 0.102 (2.59) 0.094 (2.39) 0.010 (0.25) 0.004 (0.10) 0.050 (1.27) BSC 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 0.090 (2.29) 10 0 0.098 (0.2482) 0.075 (0.1905) PRINTED IN U.S.A. PIN 1 0.157 (3.99) 0.150 (3.81) 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