Precision, Very Low Noise, Low Input Bias Current, Wide Bandwidth JFET Operational Amplifier AD8610/AD8620 FEATURES Low Noise 6 nV/√Hz Low Offset Voltage: 100 V Max Low Input Bias Current 10 pA Max Fast Settling: 600 ns to 0.01% Low Distortion Unity Gain Stable No Phase Reversal Dual-Supply Operation: ⴞ5 V to ⴞ13 V APPLICATIONS Photodiode Amplifier ATE Instrumentation Sensors and Controls High Performance Filters Fast Precision Integrators High Performance Audio GENERAL DESCRIPTION The AD8610/AD8620 is a very high precision JFET input amplifier featuring ultralow offset voltage and drift, very low input voltage and current noise, very low input bias current, and wide bandwidth. Unlike many JFET amplifiers, the AD8610/AD8620 input bias current is low over the entire operating temperature range. The AD8610/AD8620 is stable with capacitive loads of over 1000 pF in noninverting unity gain; much larger capacitive loads can be driven easily at higher noise gains. The AD8610/AD8620 swings to within 1.2 V of the supplies even with a 1 kΩ load, maximizing dynamic range even with limited supply voltages. Outputs slew at 50 V/µs in either inverting or noninverting gain configurations, and settle to 0.01% accuracy in less than 600 ns. Combined with the high input impedance, great precision, and very high output drive, the FUNCTIONAL BLOCK DIAGRAMS 8-Lead MSOP and SOIC (RM-8 and R-8 Suffixes) NULL ⴚIN ⴙIN Vⴚ 1 8 AD8610 4 5 NC Vⴙ OUT NULL NC = NO CONNECT 8-Lead SOIC (R-8 Suffix) OUTA ⴚINA ⴙINA Vⴚ 1 8 AD8620 4 5 Vⴙ OUTB ⴚINB ⴙINB AD8610/AD8620 is an ideal amplifier for driving high performance A/D inputs and buffering D/A converter outputs. Applications for the AD8610/AD8620 include electronic instruments; ATE amplification, buffering, and integrator circuits; CAT/MRI/ultrasound medical instrumentation; instrumentation quality photodiode amplification; fast precision filters (including PLL filters); and high quality audio. The AD8610/AD8620 is fully specified over the extended industrial (–40°C to +125°C) temperature range. The AD8610 is available in the narrow 8-lead SOIC and the tiny MSOP8 surface-mount packages. The AD8620 is available in the narrow 8-lead SOIC package. MSOP8 packaged devices are available only in tape and reel. REV. D 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. 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: 781/326-8703 © 2004 Analog Devices, Inc. All rights reserved. AD8610/AD8620–SPECIFICATIONS (@ V = ⴞ5.0 V, V S Parameter Symbol INPUT CHARACTERISTICS Offset Voltage (AD8610B) VOS CM = 0 V, TA = 25ⴗC, unless otherwise noted.) Conditions Min –40°C < TA < +125°C Offset Voltage (AD8620B) VOS Offset Voltage (AD8610A/AD8620A) VOS –40°C < TA < +125°C +25°C < TA < 125°C –40°C < TA < +125°C Input Bias Current IB –40°C < TA < +85°C –40°C < TA < +125°C Input Offset Current IOS –40°C < TA < +85°C –40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift (AD8610B) Offset Voltage Drift (AD8620B) Offset Voltage Drift (AD8610A/AD8620A) –10 –250 –2.5 –10 –75 –150 –2 90 100 CMRR AVO ∆VOS/∆T ∆VOS/∆T ∆VOS/∆T VCM = –2.5 V to +1.5 V RL = 1 kΩ, VO = –3 V to +3 V –40°C < TA < +125°C –40°C < TA < +125°C –40°C < TA < +125°C OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current VOH VOL IOUT RL = 1 kΩ, –40°C < TA < +125°C RL = 1 kΩ, –40°C < TA < +125°C VOUT > ± 2 V 3.8 POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier PSRR ISY VS = ± 5 V to ± 13 V VO = 0 V –40°C < TA < +125°C 100 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Settling Time SR GBP tS RL = 2 kΩ 40 en p-p en in CIN NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Input Capacitance Differential Common-Mode Channel Separation f = 10 kHz f = 300 kHz Typ Max Unit 45 80 45 80 85 90 150 +2 +130 +1.5 +1 +20 +40 100 200 150 300 250 350 850 +10 +250 +2.5 +10 +75 +150 +3 µV µV µV µV µV µV µV pA pA nA pA pA pA V dB V/mV µV/°C µV/°C µV/°C 95 180 0.5 0.5 0.8 4 –4 ± 30 110 2.5 3.0 1 1.5 3.5 –3.8 3.0 3.5 V V mA dB mA mA AV = +1, 4 V Step, to 0.01% 50 25 350 V/µs MHz ns 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.8 6 5 µV p-p nV/√Hz fA/√Hz 8 15 pF pF 137 120 dB dB CS Specifications subject to change without notice. –2– REV. D AD8610/AD8620 ELECTRICAL SPECIFICATIONS (@ V = ⴞ13 V, V S Parameter Symbol INPUT CHARACTERISTICS Offset Voltage (AD8610B) VOS CM = 0 V, TA = 25ⴗC, unless otherwise noted.) Conditions Min –40°C < TA < +125°C Offset Voltage (AD8620B) VOS Offset Voltage (AD8610A/AD8620A) VOS –40°C < TA < +125°C +25°C < TA < 125°C –40°C < TA < +125°C Input Bias Current IB –40°C < TA < +85°C –40°C < TA < +125°C Input Offset Current IOS –40°C < TA < +85°C –40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift (AD8610B) Offset Voltage Drift (AD8620B) Offset Voltage Drift (AD8610A/AD8620A) –10 –250 –3.5 –10 –75 –150 –10.5 90 100 Typ Max Unit 45 80 45 80 85 90 150 +3 +130 100 200 150 300 250 350 850 +10 +250 +3.5 +10 +75 +150 +10.5 µV µV µV µV µV µV µV pA pA nA pA pA pA V dB V/mV µV/°C µV/°C µV/°C +1.5 +20 +40 CMRR AVO ∆VOS/∆T ∆VOS/∆T ∆VOS/∆T VCM = –10 V to +10 V RL = 1 kΩ, VO = –10 V to +10 V –40°C < TA < +125°C –40°C < TA < +125°C –40°C < TA < +125°C OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Short Circuit Current VOH VOL IOUT ISC RL = 1 kΩ, –40°C < TA < +125°C RL = 1 kΩ, –40°C < TA < +125°C VOUT > 10 V +11.75 +11.84 V –11.84 –11.75 V ± 45 mA ± 65 mA POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier PSRR ISY VS = ± 5 V to ± 13 V VO = 0 V –40°C < TA < +125°C 100 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Settling Time SR GBP tS RL = 2 kΩ 40 en p-p en in CIN NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Input Capacitance Differential Common-Mode Channel Separation f = 10 kHz f = 300 kHz 110 3.0 3.5 1 1.5 3.5 3.5 4.0 dB mA mA AV = 1, 10 V Step, to 0.01% 60 25 600 V/µs MHz ns 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.8 6 5 µV p-p nV/√Hz fA/√Hz 8 15 pF pF 137 120 dB dB CS Specifications subject to change without notice. REV. D 110 200 0.5 0.5 0.8 –3– AD8610/AD8620 ABSOLUTE MAXIMUM RATINGS* Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 V Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VS–– to VS+ Differential Input Voltage . . . . . . . . . . . . . . . ± Supply Voltage Output Short-Circuit Duration to GND . . . . . . . . . . Indefinite Storage Temperature Range R, RM Packages . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C Operating Temperature Range AD8610/AD8620 . . . . . . . . . . . . . . . . . . . . –40°C to +125°C Junction Temperature Range R, RM Packages . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C Lead Temperature Range (Soldering, 10 sec) . . . . . . . . 300°C Package Type JA* JC Unit 8-Lead MSOP (RM) 8-Lead SOIC (RN) 190 158 44 43 °C/W °C/W *θJA is specified for worst-case conditions; i.e., θJA is specified for a device soldered in circuit board for surface-mount packages. *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 listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ORDERING GUIDE Model Temperature Range Package Description Package Option AD8610AR AD8610AR-REEL AD8610AR-REEL7 AD8610ARM-REEL AD8610ARM-R2 AD8610ARZ* AD8610ARZ-REEL* AD8610ARZ-REEL7* AD8610BR AD8610BR-REEL AD8610BR-REEL7 AD8610BRZ* AD8610BRZ-REEL* AD8610BRZ-REEL7* AD8620AR AD8620AR-REEL AD8620AR-REEL7 AD8620BR AD8620BR-REEL AD8620BR-REEL7 –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC RN-8 RN-8 RN-8 RM-8 RM-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 RN-8 Branding B0A B0A *Pb-free part CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD8610/AD8620 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. –4– REV. D Typical Performance Characteristics–AD8610/AD8620 600 14 18 VS = ⴞ13V 10 8 6 4 2 0 200 0 ⴚ200 ⴚ400 ⴚ150 50 150 ⴚ50 INPUT OFFSET VOLTAGE – V ⴚ250 ⴚ40 250 25 85 TEMPERATURE – ⴗC 12 10 8 6 4 VS = ⴞ13V 3.4 0 –200 –400 INPUT BIAS CURRENT – pA NUMBER OF AMPLIFIERS 400 10 8 6 4 2 –40 25 85 TEMPERATURE – ⴗC TPC 4. Input Offset Voltage vs. Temperature at ±5 V (300 Amplifiers) 3.2 3.0 2.8 2.6 2.4 2.2 2.0 0 125 0 0.2 0.6 1.0 1.4 1.8 2.2 2.6 TPC 5. Input Offset Voltage Drift 0 5 10 ⴚ5 COMMON-MODE VOLTAGE – V TPC 6. Input Bias Current vs. Common-Mode Voltage 3.05 2.65 VS = ⴞ13V VS = ⴞ5V 2.60 2.0 1.5 1.0 0.5 2.95 SUPPLY CURRENT – mA SUPPLY CURRENT – mA 2.5 0 ⴚ10 TCVOS – V/ⴗC 3.0 250 3.6 VS = ⴞ5V OR ⴞ13V 12 200 ⴚ150 50 150 ⴚ50 INPUT OFFSET VOLTAGE – V TPC 3. Input Offset Voltage at ± 5 V 14 VS = ⴞ5V –600 0 ⴚ250 125 TPC 2. Input Offset Voltage vs. Temperature at ± 13 V (300 Amplifiers) 600 INPUT OFFSET VOLTAGE – V 14 2 ⴚ600 TPC 1. Input Offset Voltage at ± 13 V SUPPLY CURRENT – mA VS = ⴞ5V 16 400 NUMBER OF AMPLIFIERS INPUT OFFSET VOLTAGE – V NUMBER OF AMPLIFIERS 12 VS = ⴞ13V 2.85 2.75 2.65 2.55 2.50 2.45 2.40 2.35 0 1 2 3 4 5 6 7 8 9 10 11 12 13 SUPPLY VOLTAGE – ⴞV TPC 7. Supply Current vs. Supply Voltage REV. D 2.55 ⴚ40 25 85 TEMPERATURE – ⴗC 125 TPC 8. Supply Current vs. Temperature at ± 13 V –5– 2.30 ⴚ40 25 85 TEMPERATURE – ⴗC 125 TPC 9. Supply Current vs. Temperature at ± 5 V AD8610/AD8620 1.2 1.0 0.8 0.6 0.4 4.10 4.05 4.00 10k 100k 1M 10M RESISTANCE LOAD – ⍀ 3.95 100M 12.05 OUTPUT VOLTAGE LOW – V 11.90 11.85 25 85 TEMPERATURE – ⴗC TPC 13. Output Voltage High vs. Temperature at ± 13 V 60 ⴚ4.20 120 80 ⴚ11.90 ⴚ11.95 ⴚ12.00 ⴚ40 125 270 225 180 135 90 20 45 0 0 ⴚ20 ⴚ45 ⴚ40 ⴚ90 ⴚ60 ⴚ135 125 10 FREQUENCY – MHz 1 100 ⴚ180 200 TPC 15. Open-Loop Gain and Phase vs. Frequency TPC 14. Output Voltage Low vs. Temperature at ± 13 V 190 260 VS = ⴞ13V VO = ⴞ10V RL = 1k⍀ 240 VS = ⴞ5V VO = ⴞ3V RL = 1k⍀ 180 170 220 G = 100 25 85 TEMPERATURE – ⴗC 40 ⴚ80 25 85 TEMPERATURE – ⴗC ⴚ40 VS = ⴞ13V RL = 1k⍀ MARKER AT 27MHz M = 69.5 CL = 20pF 100 60 VS = ⴞ13V RL = 2k⍀ CL = 20pF 40 ⴚ4.15 TPC 12. Output Voltage Low vs. Temperature at ± 5 V ⴚ11.85 ⴚ12.05 125 ⴚ4.10 ⴚ4.30 125 VS = ⴞ13V RL = 1k⍀ 11.95 ⴚ40 25 85 TEMPERATURE – ⴗC ⴚ11.80 12.00 11.80 ⴚ40 TPC 11. Output Voltage High vs. Temperature at ± 5 V VS = ⴞ13V RL = 1k⍀ ⴚ4.05 ⴚ4.25 GAIN – dB 1k TPC 10. Output Voltage to Supply Rail vs. Load AVO – V/mV 160 20 G = 10 0 G=1 200 AVO – V/mV OUTPUT VOLTAGE HIGH – V ⴚ4.00 4.15 0.2 0 100 CLOSED-LOOP GAIN – dB 4.20 VS = ⴞ5V RL = 1k⍀ 180 160 ⴚ20 110 100 1k 10k 100k 1M 10M FREQUENCY – Hz 100M TPC 16. Closed-Loop Gain vs. Frequency 140 120 120 ⴚ40 150 130 140 ⴚ40 25 85 TEMPERATURE – ⴗC 125 TPC 17. AVO vs. Temperature at ± 13 V –6– PHASE – Degrees 1.4 ⴚ3.95 VS = ⴞ5V RL = 1k⍀ OUTPUT VOLTAGE LOW – V 4.25 VS = ⴞ13V 1.6 OUTPUT VOLTAGE HIGH – V OUTPUT VOLTAGE TO SUPPLY RAIL– V 1.8 100 ⴚ40 25 85 TEMPERATURE – ⴗC 125 TPC 18. AVO vs. Temperature at ± 5 V REV. D AD8610/AD8620 160 160 VS = ⴞ13V 140 100 100 +PSRR 80 –PSRR 40 PSRR – dB 120 80 PSRR – dB PSRR – dB 121 120 120 60 122 VS = ⴞ5V 140 +PSRR 60 –PSRR 40 20 20 0 0 –20 –20 119 118 117 –40 100 1k 10k 100k 1M FREQUENCY – Hz –40 100 10M 60M TPC 19. PSRR vs. Frequency at ± 13 V 1k 10k 100k 1M FREQUENCY – Hz 10M 60M TPC 20. PSRR vs. Frequency at ± 5 V 116 ⴚ40 25 85 TEMPERATURE – ⴗC TPC 21. PSRR vs. Temperature 140 VS = ⴞ13V VOLTAGE – 300mV/DIV CMRR – dB 100 80 60 40 VOLTAGE – 300mV/DIV VS = ⴞ13V VIN = ⴚ300mV p-p AV = ⴚ100 RL = 10k⍀ 120 0V VIN VOUT CH2 = 5V/DIV 125 VS = ⴞ13V VIN = 300mV p-p AV = ⴚ100 RL = 10k⍀ CL = 0pF VIN 0V 0V VOUT 20 0 10 CH2 = 5V/DIV 0V 100 1k 10k 100k 1M FREQUENCY – Hz 10M 60M TPC 22. CMRR vs. Frequency TIME – 4s/DIV TIME – 4s/DIV TPC 23. Positive Overvoltage Recovery 100 VSY = ⴞ13V Hz 80 70 100 REV. D GAIN = 1 50 40 30 GAIN = 100 GAIN = 10 20 10 1 10 100 1k 10k 100k FREQUENCY – Hz TPC 25. 0.1 Hz to 10 Hz Input Voltage Noise 60 10 1 TIME – 1s/DIV VS = ⴞ13V 90 ZOUT – ⍀ VOLTAGE NOISE DENSITY – nV/ P-P VOLTAGE NOISE – 1V/DIV 1,000 VS = ⴞ13V VIN p-p = 1.8V TPC 24. Negative Overvoltage Recovery TPC 26. Input Voltage Noise vs. Frequency –7– 1M 0 1k 10k 100k 1M 10M FREQUENCY – Hz 100M TPC 27. ZOUT vs. Frequency AD8610/AD8620 2500 80 70 2000 60 IB – pA GAIN = 1 50 1500 40 1000 GAIN = 10 30 GAIN = 100 20 500 10 0 1k 0 10k 100k 1M FREQUENCY – Hz 10M 100M 25 20 15 +OS 30 25 20 5 1 125 15 +OS VIN ⴚOS VOUT 10 0 10 10 100 1k CAPACITANCE – pF 10k TPC 30. Small Signal Overshoot vs. Load Capacitance 5 1 ⴚOS 10 VS = ⴞ13V VIN = ⴞ14V AV = +1 FREQ = 0.5kHz VS = ⴞ5V RL = 2k⍀ VIN = 100mV 35 85 25 TEMPERATURE – ⴗC VOLTAGE – 5V/DIV SMALL SIGNAL OVERSHOOT – % 40 30 0 0 TPC 29. Input Bias Current vs. Temperature TPC 28. ZOUT vs. Frequency VS = ⴞ13V RL = 2k⍀ VIN = 100mV p-p 35 VOLTAGE – 5V/DIV ZOUT – ⍀ 40 3000 VS = ⴞ5V 90 SMALL SIGNAL OVERSHOOT – % 100 100 1k TIME – 400s/DIV 10k VS = ⴞ13V VIN p-p = 20V AV = +1 RL = 2k⍀ CL = 20pF TIME – 1s/DIV CAPACITANCE – pF TIME – 400ns/DIV TPC 34. +SR at G = +1 TPC 33. Large Signal Response at G = +1 VOLTAGE – 5V/DIV VS = ⴞ13V VIN p-p = 20V AV = +1 RL = 2k⍀ CL = 20pF TPC 32. No Phase Reversal VOLTAGE – 5V/DIV VOLTAGE – 5V/DIV TPC 31. Small Signal Overshoot vs. Load Capacitance VS = ⴞ13V VIN p-p = 20V AV = +1 RL = 2k⍀ CL = 20pF TIME – 400ns/DIV TPC 35. –SR at G = +1 –8– VS = ⴞ13V VIN p-p = 20V AV = ⴚ1 RL = 2k⍀ CL = 20pF TIME – 1s/DIV TPC 36. Large Signal Response at G = –1 REV. D VS = ⴞ13V VIN p-p = 20V AV = ⴚ1 RL = 2k⍀ SR = 50V/s CL = 20pF VOLTAGE – 5V/DIV VOLTAGE – 5V/DIV AD8610/AD8620 VS = ⴞ13V VIN p-p = 20V AV = ⴚ1 RL = 2k⍀ SR = 55V/s CL = 20pF TIME – 400ns/DIV TIME – 400ns/DIV TPC 37. +SR at G = –1 CS(dB) = 20 log (VOUT / 10 ⴛ VIN) 2 V– + – 0 136 20k⍀ R2 R4 2k⍀ V– 6 5 V+ 7 2k⍀ U2 134 2k⍀ 0 132 0 –13V 0 0 130 CS – dB VIN 20V p-p U1 V+ 138 R1 +13V 3 TPC 38. –SR at G = –1 Figure 1. Channel Separation Test Circuit 126 FUNCTIONAL DESCRIPTION The AD8610/AD8620 is manufactured on Analog Devices, Inc.’s proprietary XFCB (eXtra Fast Complementary Bipolar) process. XFCB is fully dielectrically isolated (DI) and used in conjunction with N-channel JFET technology and trimmable thin-film resistors to create the world’s most precise JFET input amplifier. Dielectrically isolated NPN and PNP transistors fabricated on XFCB have FT greater than 3 GHz. Low TC thin film resistors enable very accurate offset voltage and offset voltage tempco trimming. These process breakthroughs allowed Analog Devices’ world class IC designers to create an amplifier with faster slew rate and more than 50% higher bandwidth at half of the current consumed by its closest competition. The AD8610 is unconditionally stable in all gains, even with capacitive loads well in excess of 1 nF. The AD8610B achieves less than 100 µV of offset and 1 µV/°C of offset drift, numbers usually associated with very high precision bipolar input amplifiers. The AD8610 is offered in the tiny 8-lead MSOP as well as narrow 8-lead SOIC surfacemount packages and is fully specified with supply voltages from ± 5 V to ± 13 V. The very wide specified temperature range, up to 125°C, guarantees superior operation in systems with little or no active cooling. 124 122 120 0 50 100 150 200 FREQUENCY – kHz 250 300 350 Figure 2. AD8620 Channel Separation Graph Power Consumption A major advantage of the AD8610/AD8620 in new designs is the saving of power. Lower power consumption of the AD8610 makes it much more attractive for portable instrumentation and for high-density systems, simplifying thermal management, and reducing power supply performance requirements. Compare the power consumption of the AD8610/AD8620 versus the OPA627 in Figure 3. 8 SUPPLY CURRENT – mA 7 The unique input architecture of the AD8610 features extremely low input bias currents and very low input offset voltage. Low power consumption minimizes the die temperature and maintains the very low input bias current. Unlike many competitive JFET amplifiers, the AD8610/AD8620 input bias currents are low even at elevated temperatures. Typical bias currents are less than 200 pA at 85°C. The gate current of a JFET doubles every 10°C resulting in a similar increase in input bias current over temperature. Special care should be given to the PC board layout to minimize leakage currents between PCB traces. Improper layout and board handling generates leakage current that exceeds the bias current of the AD8610/AD8620. REV. D 128 OPA627 6 5 4 3 AD8610 2 –75 –50 –25 0 25 50 75 100 125 TEMPERATURE – ⴗC Figure 3. Supply Current vs. Temperature –9– AD8610/AD8620 +5V Driving Large Capacitive Loads 3 The AD8610 has excellent capacitive load driving capability and can safely drive up to 10 nF when operating with ± 5 V supply. Figures 4 and 5 compare the AD8610/AD8620 against the OPA627 in the noninverting gain configuration driving a 10 kΩ resistor and 10,000 pF capacitor placed in parallel on its output, with a square wave input set to a frequency of 200 kHz. The AD8610 has much less ringing than the OPA627 with heavy capacitive loads. VIN = 50mV 7 2 4 –5V 2k⍀ 2F 2k⍀ Figure 6. Capacitive Load Drive Test Circuit VS = ⴞ5V RL = 10k⍀ CL = 10,000pF VOLTAGE – 20mV/DIV VOLTAGE – 50mV/DIV VS = ⴞ5V RL = 10k⍀ CL = 2F TIME – 2s/DIV TIME – 20s/DIV Figure 4. OPA627 Driving CL = 10,000 pF Figure 7. OPA627 Capacitive Load Drive, AV = +2 VS = ⴞ5V RL = 10k⍀ CL = 10,000pF VOLTAGE – 50mV/DIV VOLTAGE – 20mV/DIV VS = ⴞ5V RL = 10k⍀ CL = 2F TIME – 2s/DIV TIME – 20s/DIV Figure 5. AD8610/AD8620 Driving CL = 10,000 pF Figure 8. AD8610/AD8620 Capacitive Load Drive, AV = +2 The AD8610/AD8620 can drive much larger capacitances without any external compensation. Although the AD8610/AD8620 is stable with very large capacitive loads, remember that this capacitive loading will limit the bandwidth of the amplifier. Heavy capacitive loads will also increase the amount of overshoot and ringing at the output. Figures 7 and 8 show the AD8610/AD8620 and the OPA627 in a noninverting gain of +2 driving 2 µF of capacitance load. The ringing on the OPA627 is much larger in magnitude and continues more than 10 times longer than the AD8610. Slew Rate (Unity Gain Inverting vs. Noninverting) Amplifiers generally have a faster slew rate in an inverting unity gain configuration due to the absence of the differential input capacitance. Figures 9 through 12 show the performance of the AD8610 configured in a gain of –1 compared to the OPA627. The AD8610 slew rate is more symmetrical, and both the positive and negative transitions are much cleaner than in the OPA627. –10– REV. D AD8610/AD8620 VS = ⴞ13V RL = 2k⍀ G = –1 VOLTAGE – 5V/DIV VOLTAGE – 5V/DIV VS = ⴞ13V RL = 2k⍀ G = –1 SR = 54V/s TIME – 400ns/DIV TIME – 400ns/DIV Figure 12. (–SR) of OPA627 in Unity Gain of –1 Figure 9. (+SR) of AD8610/AD8620 in Unity Gain of –1 VS = ⴞ13V RL = 2k⍀ G = –1 VOLTAGE – 5V/DIV SR = 56V/s SR = 42.1V/s TIME – 400ns/DIV Figure 10. (+SR) of OPA627 in Unity Gain of –1 The AD8610 has a very fast slew rate of 60 V/µs even when configured in a noninverting gain of +1. This is the toughest condition to impose on any amplifier since the input common-mode capacitance of the amplifier generally makes its SR appear worse. The slew rate of an amplifier varies according to the voltage difference between its two inputs. To observe the maximum SR as specified in the AD8610 data sheet, a difference voltage of about 2 V between the inputs must be ensured. This will be required for virtually any JFET op amp so that one side of the op amp input circuit is completely off, maximizing the current available to charge and discharge the internal compensation capacitance. Lower differential drive voltages will produce lower slew rate readings. A JFETinput op amp with a slew rate of 60 V/µs at unity gain with VIN = 10 V might slew at 20 V/µs if it is operated at a gain of +100 with VIN = 100 mV. The slew rate of the AD8610/AD8620 is double that of the OPA627 when configured in a unity gain of +1 (see Figures 13 and 14). VS = ⴞ13V RL = 2k⍀ G = +1 VOLTAGE – 5V/DIV VOLTAGE – 5V/DIV VS = ⴞ13V RL = 2k⍀ G = –1 SR = 54V/s SR = 85V/s TIME – 400ns/DIV TIME – 400ns/DIV Figure 11. (–SR) of AD8610/AD8620 in Unity Gain of –1 Figure 13. (+SR) of AD8610/AD8620 in Unity Gain of +1 REV. D –11– AD8610/AD8620 diodes greatly interfere with many application circuits such as precision rectifiers and comparators. The AD8610 is free from these limitations. VS = ⴞ13V RL = 2k⍀ G = +1 VOLTAGE – 5V/DIV +13V 3 V1 SR = 23V/s 7 6 2 4 AD8610 14V 0 –13V Figure 16. Unity Gain Follower No Phase Reversal TIME – 400ns/DIV Figure 14. (+SR) of OPA627 in Unity Gain of +1 The slew rate of an amplifier determines the maximum frequency at which it can respond to a large signal input. This frequency (known as full-power bandwidth, or FPBW) can be calculated from the equation: SR FPBW = (2π ×VPEAK ) Many amplifiers misbehave when one or both of the inputs are forced beyond the input common-mode voltage range. Phase reversal is typified by the transfer function of the amplifier, effectively reversing its transfer polarity. In some cases, this can cause lockup and even equipment damage in servo systems, and may cause permanent damage or nonrecoverable parameter shifts to the amplifier itself. Many amplifiers feature compensation circuitry to combat these effects, but some are only effective for the inverting input. The AD8610/AD8620 is designed to prevent phase reversal when one or both inputs are forced beyond their input common-mode voltage range. for a given distortion (e.g., 1%). VIN VOLTAGE – 5V/DIV CH1 = 20.8Vp-p VOLTAGE – 10V/DIV 0V CH2 = 19.4Vp-p VOUT 0V 0 TIME – 400s/DIV Figure 17. No Phase Reversal TIME – 400ns/DIV THD Readings vs. Common-Mode Voltage Input Overvoltage Protection When the input of an amplifier is driven below VEE or above VCC by more than one VBE, large currents will flow from the substrate through the negative supply (V–) or the positive supply (V+), respectively, to the input pins, which can destroy the device. If the input source can deliver larger currents than the maximum forward current of the diode (>5 mA), a series resistor can be added to protect the inputs. With its very low input bias and offset current, a large series resistor can be placed in front of the AD8610 inputs to limit current to below damaging levels. Series resistance of 10 kΩ will generate less than 25 µV of offset. This 10 kΩ will allow input voltages more than 5 V beyond either power supply. Thermal noise generated by the resistor will add 7.5 nV/√Hz to the noise of the AD8610. For the AD8610/AD8620, differential voltages equal to the supply voltage will not cause any problem (see Figure 15). In this context, it should also be noted that the high breakdown voltage of the input FETs eliminates the need to include clamp diodes between the inputs of the amplifier, a practice that is mandatory on many precision op amps. Unfortunately, clamp Total harmonic distortion of the AD8610/AD8620 is well below 0.0006% with any load down to 600 Ω. The AD8610/AD8620 outperforms the OPA627 for distortion, especially at frequencies above 20 kHz. 0.1 VSY = ⴞ13V VIN = 5V rms BW = 80kHz 0.01 THD+N – % Figure 15. AD8610 FPBW OPA627 0.001 AD8610 0.0001 10 100 1k FREQUENCY – Hz 10k 80k Figure 18. AD8610 vs. OPA627 THD + Noise @ VCM = 0 V –12– REV. D AD8610/AD8620 0.1 1.2k VSY = ⴞ13V RL = 600⍀ SETTLING TIME – ns THD + N – % 1.0k 2V rms 0.01 4V rms 800 600 400 6V rms OPA627 200 0.001 10 100 1k FREQUENCY – Hz 10k 0 0.001 20k 0.01 0.1 ERROR BAND – % 1 10 Figure 21. OPA627 Settling Time vs. Error Band Figure 19. THD + Noise vs. Frequency The AD8610/AD8620 maintains this fast settling when loaded with large capacitive loads as shown in Figure 22. Noise vs. Common-Mode Voltage AD8610 noise density varies only 10% over the input range as shown in Table I. 3.0 ERROR BAND ⴞ0.01% Table I. Noise vs. Common-Mode Voltage 2.5 Noise Reading (nV/√Hz) –10 –5 0 +5 +10 7.21 6.89 6.73 6.41 7.21 SETTLING TIME – s VCM at F = 1 kHz (V) Settling Time 2.0 1.5 1.0 0.5 The AD8610 has a very fast settling time, even to a very tight error band, as can be seen from Figure 20. The AD8610 is configured in an inverting gain of +1 with 2 kΩ input and feedback resistors. The output is monitored with a 10 ×, 10 M, 11.2 pF scope probe. 0.0 0 500 1000 CL – pF 1500 2000 Figure 22. AD8610 Settling Time vs. Load Capacitance 1.2k 3.0 ERROR BAND ⴞ0.01% 2.5 800 SETTLING TIME – s SETTLING TIME – ns 1.0k 600 400 200 2.0 1.5 1.0 0.5 0 0.001 0.01 0.1 ERROR BAND – % 1 10 0.0 Figure 20. AD8610 Settling Time vs. Error Band 0 500 1000 CL – pF 1500 2000 Figure 23. OPA627 Settling Time vs. Load Capacitance Output Current Capability The AD8610 can drive very heavy loads due to its high output current. It is capable of sourcing or sinking 45 mA at ±10 V output. The short circuit current is quite high and the part is capable of sinking about 95 mA and sourcing over 60 mA while operating with REV. D –13– AD8610/AD8620 supplies of ± 5 V. Figures 24 and 25 compare the load current versus output voltage of AD8610/AD8620 and OPA627. Programmable Gain Amplifier (PGA) The combination of low noise, low input bias current, low input offset voltage, and low temperature drift make the AD8610 a perfect solution for programmable gain amplifiers. PGAs are often used immediately after sensors to increase the dynamic range of the measurement circuit. Historically, the large ON resistance of switches, combined with the large IB currents of amplifiers, created a large dc offset in PGAs. Recent and improved monolithic switches and amplifiers completely remove these problems. A PGA discrete circuit is shown in Figure 27. In Figure 27, when the 10 pA bias current of the AD8610 is dropped across the (<5 Ω) RON of the switch, it results in a negligible offset error. DELTA FROM RESPECTIVE RAIL – V 10 1 VEE VCC When high precision resistors are used, as in the circuit of Figure 27, the error introduced by the PGA is within the 1/2 LSB requirement for a 16-bit system. 0.1 0.00001 0.0001 0.001 0.01 LOAD CURRENT – A 0.1 +5V 1 Figure 24. AD8610 Dropout from ± 13 V vs. Load Current VIN 100⍀ 10 AD8610 VOUT U10 DELTA FROM RESPECTIVE RAIL – V 5 10k⍀ VCC 5pF –5V +5V VEE 1 12 VL 1 +5V 13 VDD 0.1 0.00001 Y0 Y1 0.0001 0.001 0.01 LOAD CURRENT – A 0.1 A0 1 A1 A Y2 B Y3 74HC139 Figure 25. OPA627 Dropout from ±15 V vs. Load Current Although operating conditions imposed on the AD8610 (± 13 V) are less favorable than the OPA627 (±15 V), it can be seen that the AD8610 has much better drive capability (lower headroom to the supply) for a given load current. Input Offset Voltage Adjustment 1k⍀ D1 2 10k⍀ S2 14 D2 15 S3 11 D3 10 S4 6 D4 7 G=1 G = 10 IN2 1k⍀ G = 100 IN3 100⍀ G = 1000 IN4 VSS GND 4 11⍀ 5 –5V Figure 27. High Precision PGA 1. Room temperature error calculation due to RON and IB: ∆VOS Total Total Total Offset of AD8610 is very small and normally does not require additional offset adjustment. However, the offset adjust pins can be used as shown in Figure 26 to further reduce the dc offset. By using resistors in the range of 50 kΩ, offset trim range is ±3.3 mV. +VS 9 8 Operating with Supplies Greater than ± 13 V The AD8610 maximum operating voltage is specified at ± 13 V. When ± 13 V is not readily available, an inexpensive LDO can provide ± 12 V from a nominal ± 15 V supply. 16 3 IN1 ADG452 G S1 = I B × RON = 2 pA × 5 Ω = 10 pV Offset = AD8610 (Offset ) + ∆VOS Offset = AD8610 (Offset _ Trimmed ) + ∆VOS Offset = 5 µ V + 10 pV ≅ 5 µ V 2. Full temperature error calculation due to RON and IB: 7 ∆VOS (@ 85°C) = I B (@ 85°C) × RON (@ 85°C) = 2 6 AD8610 3 250 pA × 15 Ω = 3.75 nV VOUT 1 5 R1 4 3. Temperature coefficient of switch and AD8610/AD8620 combined is essentially the same as the TCVOS of the AD8610: ∆VOS /∆T (total ) = ∆VOS /∆T ( AD8610 ) + ∆VOS /∆T ( I B × RON ) ∆VOS /∆T (total ) = 0.5 µ V/ ° C+ 0.06 nV/ ° C ≅ 0.5 µ V/ ° C –VS Figure 26. Offset Voltage Nulling Circuit –14– REV. D AD8610/AD8620 High Speed Instrumentation Amplifier (IN AMP) The three op amp instrumentation amplifiers shown in Figure 28 can provide a range of gains from unity up to 1,000 or higher. The instrumentation amplifier configuration features high commonmode rejection, balanced differential inputs, and stable, accurately defined gain. Low input bias currents and fast settling are achieved with the JFET input AD8610/AD8620. Most instrumentation amplifiers cannot match the high frequency performance of this circuit. The circuit bandwidth is 25 MHz at a gain of 1, and close to 5 MHz at a gain of 10. Settling time for the entire circuit is 550 ns to 0.01% for a 10 V step (gain = 10). Note that the resistors around the input pins need to be small enough in value so that the RC time constant they form in combination with stray circuit capacitance does not reduce circuit bandwidth. V+ VIN1 In active filter applications using operational amplifiers, the dc accuracy of the amplifier is critical to optimal filter performance. The amplifier’s offset voltage and bias current contribute to output error. Input offset voltage is passed by the filter, and may be amplified to produce excessive output offset. For low frequency applications requiring large value input resistors, bias and offset currents flowing through these resistors will also generate an offset voltage. At higher frequencies, an amplifier’s dynamic response must be carefully considered. In this case, slew rate, bandwidth, and openloop gain play a major role in amplifier selection. The slew rate must be both fast and symmetrical to minimize distortion. The amplifier’s bandwidth, in conjunction with the filter’s gain, will dictate the frequency response of the filter. The use of a high performance amplifier such as the AD8610/AD8620 will minimize both dc and ac errors in all active filter applications. Second-Order Low-Pass Filter Figure 29 shows the AD8610 configured as a second-order Butterworth low-pass filter. With the values as shown, the corner frequency of the filter will be 1 MHz. The wide bandwidth of the AD8610/AD8620 allows a corner frequency up to tens of megaHertz. The following equations can be used for component selection: 1/2 AD8620 U1 V– C5 10pF R1 = R2 = User Selected (Typical Values: 10 k Ω − 100 k Ω) V+ R1 1k⍀ R4 2k⍀ C4 15pF R7 2k⍀ VOUT AD8610 R8 2k⍀ 1.414 (2π )( fCUTOFF )(R1) C2 = 0.707 2 π f ( )( CUTOFF )(R1) U2 R6 2k⍀ RG C1 = V– where C1 and C2 are in farads. R5 2k⍀ C1 22pF C3 15pF VIN2 1/2 AD8620 +13V U1 VIN R2 1k⍀ 5 R2 10k⍀ C2 10pF R1 10k⍀ AD8610 VOUT U1 C2 11pF Figure 28. High Speed Instrumentation Amplifier High Speed Filters –13V The four most popular configurations are Butterworth, Elliptical, Bessel, and Chebyshev. Each type has a response that is optimized for a given characteristic as shown in Table II. Figure 29. Second-Order Low-Pass Filter Table II. Filter Types REV. D Type Sensitivity Overshoot Butterworth Chebyshev Elliptical Bessel (Thompson) Moderate Good Best Poor Good Moderate Poor Best –15– Phase Amplitude (Pass Band) Nonlinear Max Flat Equal Ripple Equal Ripple Linear AD8610/AD8620 High Speed, Low Noise Differential Driver The AD8620 is a perfect candidate as a low noise differential driver for many popular ADCs. There are also other applications, such as balanced lines, that require differential drivers. The circuit of Figure 30 is a unique line driver widely used in industrial applications. With ±13 V supplies, the line driver can deliver a differential signal of 23 V p-p into a 1 kΩ load. The high slew rate and wide bandwidth of the AD8620 combine to yield a full power bandwidth of 145 kHz while the low noise front end produces a referred-toinput noise voltage spectral density of 6 nV/√Hz. The design is a transformerless, balanced transmission system where output common-mode rejection of noise is of paramount importance. Like the transformer-based design, either output can be shorted to ground for unbalanced line driver applications without changing the circuit gain of 1. This allows the design to be easily set to noninverting, inverting, or differential operation. –16– U2 3 R4 3 2 R8 V+ V– V+ 1k⍀ V– 1/2 OF AD8620 2 VO1 1 1k⍀ R10 50⍀ 6 AD8610 R1 1k⍀ 0 R9 R12 1k⍀ R6 10k⍀ R7 1k⍀ 1k⍀ 5 R3 R13 1k⍀ R5 1k⍀ V+ 7 1k⍀ V– 6 U3 1/2 OF AD8620 R2 1k⍀ R11 50⍀ VO2 VO2 – VO1 = V IN 0 Figure 30. Differential Driver REV. D AD8610/AD8620 OUTLINE DIMENSIONS 8-Lead Mini Small Outline Package [MSOP] (RM-8) 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) Dimensions shown in millimeters Dimensions shown in millimeters and (inches) 3.00 BSC 8 5.00 (0.1968) 4.80 (0.1890) 5 4.90 BSC 3.00 BSC 1 4.00 (0.1574) 3.80 (0.1497) 4 8 5 1 4 6.20 (0.2440) 5.80 (0.2284) PIN 1 1.27 (0.0500) BSC 0.65 BSC 0.25 (0.0098) 0.10 (0.0040) 1.10 MAX 0.15 0.00 0.38 0.22 COPLANARITY 0.10 0.23 0.08 8ⴗ 0ⴗ 0.80 0.60 0.40 COPLANARITY SEATING 0.10 PLANE SEATING PLANE 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) ⴛ 45ⴗ 0.25 (0.0099) 8ⴗ 0.25 (0.0098) 0ⴗ 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN COMPLIANT TO JEDEC STANDARDS MO-187AA REV. D 1.75 (0.0688) 1.35 (0.0532) –17– AD8610/AD8620 Revision History Location Page 2/04—Data Sheet changed from REV. C to REV. D. Changes to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Changes to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 10/02—Data Sheet changed from REV. B to REV. C. Updated ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Edits to Figure 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5/02—Data Sheet changed from REV. A to REV. B. Addition of part number AD8620 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Universal Addition of 8-Lead SOIC (R-8 Suffix) Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Changes to GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Additions to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Change to ELECTRICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Additions to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Replace TPC 29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Add Channel Separation Test Circuit Figure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Add Channel Separation Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Changes to Figure 26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Addition of High-Speed, Low Noise Differential Driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Addition of Figure 30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 –18– REV. D –19– –20– C02730–0–2/04(D)