Precision, Very Low Noise, Low Input Bias Current, Wide Bandwidth JFET Operational Amplifiers AD8610/AD8620 APPLICATIONS Photodiode amplifiers ATE Instrumentation Sensors and controls High performance filters Fast precision integrators High performance audio PIN CONFIGURATIONS NULL 1 -IN 2 AD8610 8 NC 7 V+ 6 OUT TOP VIEW V- 4 (Not to Scale) 5 NULL +IN 3 NC = NO CONNECT 02730-001 Low noise: 6 nV/Hz Low offset voltage: 100 V maximum Low input bias current: 10 pA maximum Fast settling: 600 ns to 0.01% Low distortion Unity gain stable No phase reversal Dual-supply operation: 5 V to 13 V Figure 1. 8-Lead MSOP and 8-Lead SOIC_N OUTA 1 -INA 2 AD8620 8 V+ 7 OUTB 6 -INB TOP VIEW V- 4 (Not to Scale) 5 +INB +INA 3 02730-002 FEATURES Figure 2. 8-Lead SOIC_N GENERAL DESCRIPTION The AD8610/AD8620 are very high precision JFET input amplifiers 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 are 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 swing to within 1.2 V of the supplies even with a 1 k load, maximizing dynamic range even with limited supply voltages. Outputs slew at 50 V/s in either inverting or noninverting gain configurations, and settle to 0.01% accuracy in less than 600 ns. Combined with high input impedance, great precision, and very high output drive, the AD8610/AD8620 are ideal amplifiers for driving high performance ADC inputs and buffering DAC 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 are fully specified over the extended industrial temperature range (-40C to +125C). The AD8610 is available in the narrow 8-lead SOIC and the tiny 8-lead MSOP surface-mount packages. The AD8620 is available in the narrow 8-lead SOIC package. The 8-lead MSOP packaged devices are avail-able only in tape and reel. Rev. F Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2001-2008 Analog Devices, Inc. All rights reserved. AD8610/AD8620 TABLE OF CONTENTS Features .............................................................................................. 1 Absolute Maximum Ratings ............................................................5 Applications ....................................................................................... 1 ESD Caution...................................................................................5 Pin Configurations ........................................................................... 1 Typical Performance Characteristics ..............................................6 General Description ......................................................................... 1 Theory of Operation ...................................................................... 13 Revision History ............................................................................... 2 Functional Description .............................................................. 13 Specifications..................................................................................... 3 Outline Dimensions ....................................................................... 22 Electrical Specifications ............................................................... 4 Ordering Guide .......................................................................... 22 REVISION HISTORY 5/08--Rev. E to Rev. F Changes to Figure 17 ........................................................................ 8 Changes to Functional Description Section ............................... 13 Changes to THD Readings vs. Common-Mode Voltage Section .............................................................................................. 17 Changes to Output Current Capability Section ......................... 18 Changes to Figure 66 and Figure 67 ............................................. 19 Changes to Figure 68 ...................................................................... 20 Replaced Second-Order Low-Pass Filter Section ....................... 20 11/06--Rev. D to Rev. E Updated Format .................................................................. Universal Changes to Table 1 ............................................................................ 3 Changes to Table 2 ............................................................................ 4 Changes to Outline Dimensions................................................... 21 Changes to Ordering Guide .......................................................... 21 2/04--Rev. C to Rev. D. Changes to Specifications .................................................................2 Changes to Ordering Guide .............................................................4 Updated Outline Dimensions ....................................................... 17 10/02--Rev. B to Rev. C. Updated Ordering Guide .................................................................4 Edits to Figure 15 ............................................................................ 12 Updated Outline Dimensions ....................................................... 16 5/02--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 Rev. F | Page 2 of 24 AD8610/AD8620 SPECIFICATIONS @ VS = 5.0 V, VCM = 0 V, TA = 25C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage (AD8610B) Symbol Conditions Min VOS -40C < TA < +125C Offset Voltage (AD8620B) VOS Offset Voltage (AD8610A/AD8620A) VOS -40C < TA < +125C 25C < TA < 125C -40C < TA < +125C Input Bias Current IB -40C < TA < +85C -40C < TA < +125C Input Offset Current IOS -40C < TA < +85C -40C < TA < +125C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift (AD8610B) Offset Voltage Drift (AD8620B) Offset Voltage Drift (AD8610A/AD8620A) OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current POWER SUPPLY Power Supply Rejection Ratio Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Settling Time NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Input Capacitance Differential Mode Common Mode Channel Separation f = 10 kHz f = 300 kHz -10 -250 -2.5 -10 -75 -150 -2 90 100 CMRR AVO VOS/T VOS/T VOS/T VCM = -1.5 V to +2.5 V RL = 1 k, VO = -3 V to +3 V -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C VOH VOL IOUT RL = 1 k, -40C < TA < +125C RL = 1 k, -40C < TA < +125C VOUT > 2 V 3.8 PSRR ISY VS = 5 V to 13 V VO = 0 V -40C < TA < +125C 100 SR GBP tS RL = 2 k 40 en p-p en in CIN 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 V V V V V V V pA pA nA pA pA pA V dB V/mV V/C V/C V/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/s MHz ns 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.8 6 5 V p-p nV/Hz fA/Hz 8 15 pF pF 137 120 dB dB CS Rev. F | Page 3 of 24 AD8610/AD8620 ELECTRICAL SPECIFICATIONS @ VS = 13 V, VCM = 0 V, TA = 25C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage (AD8610B) Symbol Conditions Min VOS -40C < TA < +125C Offset Voltage (AD8620B) VOS Offset Voltage (AD8610A/AD8620A) VOS -40C < TA < +125C 25C < TA < 125C -40C < TA < +125C Input Bias Current IB -40C < TA < +85C -40C < TA < +125C Input Offset Current IOS -40C < TA < +85C -40C < TA < +125C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift (AD8610B) Offset Voltage Drift (AD8620B) Offset Voltage Drift (AD8610A/AD8620A) OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Short-Circuit Current POWER SUPPLY Power Supply Rejection Ratio Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Settling Time NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Input Capacitance Differential Mode Common Mode Channel Separation f = 10 kHz f = 300 kHz -10 -250 -3.5 -10 -75 -150 -10.5 90 100 CMRR AVO VOS/T VOS/T VOS/T VCM = -10 V to +10 V RL = 1 k, VO = -10 V to +10 V -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C VOH VOL IOUT ISC RL = 1 k, -40C < TA < +125C RL = 1 k, -40C < TA < +125C VOUT > 10 V +11.75 PSRR ISY VS = 5 V to 13 V VO = 0 V -40C < TA < +125C 100 SR GBP tS RL = 2 k 40 en p-p en in CIN 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 V V V V V V V pA pA nA pA pA pA V dB V/mV V/C V/C V/C +1.5 +20 +40 110 200 0.5 0.5 0.8 +11.84 -11.84 45 65 110 3.0 3.5 1 1.5 3.5 -11.75 3.5 4.0 V V mA mA dB mA mA AV = +1, 10 V step, to 0.01% 60 25 600 V/s MHz ns 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.8 6 5 V p-p nV/Hz fA/Hz 8 15 pF pF 137 120 dB dB CS Rev. F | Page 4 of 24 AD8610/AD8620 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration to GND Storage Temperature Range Operating Temperature Range Junction Temperature Range Lead Temperature (Soldering, 10 sec) Rating 27.3 V VS- to VS+ Supply voltage Indefinite -65C to +150C -40C to +125C -65C to +150C 300C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 4. Thermal Resistance Package Type 8-Lead MSOP (RM) 8-Lead SOIC (R) 1 JA1 190 158 JC 44 43 Unit C/W C/W JA is specified for worst-case conditions, that is, JA is specified for a device soldered in circuit board for surface-mount packages. ESD CAUTION Rev. F | Page 5 of 24 AD8610/AD8620 TYPICAL PERFORMANCE CHARACTERISTICS 14 600 VS = 13V VS = 5V INPUT OFFSET VOLTAGE (V) 10 8 6 4 400 200 0 -200 -400 02730-003 2 0 -250 -150 -50 50 150 02730-006 NUMBER OF AMPLIFIERS 12 -600 250 -40 25 INPUT OFFSET VOLTAGE (V) Figure 3. Input Offset Voltage 14 VS = 5V OR 13V 12 400 NUMBER OF AMPLIFIERS 200 0 -200 -400 25 85 8 6 4 2 02730-004 -40 10 0 125 02730-007 INPUT OFFSET VOLTAGE (V) VS = 13V 0 0.2 0.6 1.0 Figure 4. Input Offset Voltage vs. Temperature at 13 V (300 Amplifiers) 1.8 2.2 2.6 Figure 7. Input Offset Voltage Drift 18 3.6 VS = 13V VS = 5V 3.4 INPUT BIAS CURRENT (pA) 14 12 10 8 6 4 -250 -150 -50 50 150 3.0 2.8 2.6 2.4 2.2 02730-005 2 3.2 2.0 250 INPUT OFFSET VOLTAGE (V) 02730-008 16 NUMBER OF AMPLIFIERS 1.4 TCVOS (V/C) TEMPERATURE (C) 0 125 Figure 6. Input Offset Voltage vs. Temperature at 5 V (300 Amplifiers) 600 -600 85 TEMPERATURE (C) -10 -5 0 5 10 COMMON-MODE VOLTAGE (V) Figure 8. Input Bias Current vs. Common-Mode Voltage Figure 5. Input Offset Voltage Rev. F | Page 6 of 24 AD8610/AD8620 3.0 2.0 1.5 1.0 0 02730-009 0.5 0 1 2 3 4 5 6 7 8 9 10 11 12 VS = 13V 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 02730-012 SUPPLY CURRENT (mA) 2.5 OUTPUT VOLTAGE TO SUPPLY RAIL (V) 1.8 0 100 13 1k SUPPLY VOLTAGE (V) Figure 9. Supply Current vs. Supply Voltage 1M 4.20 OUTPUT VOLTAGE HIGH (V) 2.85 2.75 2.65 4.15 4.10 4.05 -40 25 85 3.95 125 02730-013 02730-010 4.00 -40 25 85 Figure 13. Output Voltage High vs. Temperature Figure 10. Supply Current vs. Temperature -3.95 2.65 VS = 5V RL = 1k VS = 5V -4.00 OUTPUT VOLTAGE LOW (V) 2.60 2.55 2.50 2.45 2.40 25 85 -4.05 -4.10 -4.15 -4.20 -4.30 125 02730-014 -4.25 02730-011 2.35 -40 125 TEMPERATURE (C) TEMPERATURE (C) SUPPLY CURRENT (mA) 100M VS = 5V RL = 1k 2.95 2.30 10M 4.25 VS = 13V SUPPLY CURRENT (mA) 100k Figure 12. Output Voltage to Supply Rail vs. Resistance Load 3.05 2.55 10k RESISTANCE LOAD () -40 25 85 125 TEMPERATURE (C) TEMPERATURE (C) Figure 14. Output Voltage Low vs. Temperature Figure 11. Supply Current vs. Temperature Rev. F | Page 7 of 24 AD8610/AD8620 60 VS = 13V RL = 1k 12.00 CLOSED-LOOP GAIN (dB) 11.95 11.90 11.85 G = +100 20 G = +10 0 G = +1 -20 -40 25 85 -40 125 02730-018 11.80 VS = 13V RL = 2k CL = 20pF 40 02730-015 OUTPUT VOLTAGE HIGH (V) 12.05 1k 10k TEMPERATURE (C) 10M 100M Figure 18. Closed-Loop Gain vs. Frequency 260 -11.80 VS = 13V RL = 1k VS = 13V VO = 10V RL = 1k 240 -11.85 220 AVO (V/mV) -11.90 -11.95 200 180 160 140 -12.00 -40 25 85 100 125 02730-019 -12.05 120 02730-016 OUTPUT VOLTAGE LOW (V) 1M FREQUENCY (Hz) Figure 15. Output Voltage High vs. Temperature -40 25 85 125 TEMPERATURE (C) TEMPERATURE (C) Figure 19. AVO vs. Temperature Figure 16. Output Voltage Low vs. Temperature 190 120 VS = 5V VO = 3V RL = 1k 180 100 170 80 AVO (V/mV) 160 60 40 150 140 130 AD8610 VS = 13V CL = 20pF 20 120 0 -20 1kHz 10kHz 100kHz 1MHz FREQUENCY 10MHz 50MHz 100 02730-020 110 02730-017 GAIN AND PHASE (dB AND DEGREES) 100k -40 25 85 TEMPERATURE (C) Figure 20. AVO vs. Temperature Figure 17. Open-Loop Gain and Phase vs. Frequency Rev. F | Page 8 of 24 125 AD8610/AD8620 160 140 VS = 13V 140 VS = 13V 120 120 100 +PSRR 80 60 CMRR (dB) PSRR (dB) 100 -PSRR 40 20 80 60 40 0 -40 100 1k 10k 100k 1M 10M 0 10 60M 02730-024 20 02730-021 -20 100 FREQUENCY (Hz) 1k 10k 100k 1M 10M 60M FREQUENCY (Hz) Figure 21. PSRR vs. Frequency Figure 24. CMRR vs. Frequency 160 VS = 13V VIN = -300mV p-p AV = -100 RL = 10k VS = 5V 140 PSRR (dB) 100 VOLTAGE (300mV/DIV) 120 +PSRR 80 60 -PSRR 40 20 0V VIN CH2 = 5V/DIV VOUT -40 100 1k 10k 100k 1M 10M 02730-025 02730-022 0 -20 0V 60M TIME (4s/DIV) FREQUENCY (Hz) Figure 25. Positive Overvoltage Recovery Figure 22. PSRR vs. Frequency 122 VS = 13V VIN = 300mV p-p AV = -100 RL = 10k CL = 0pF VOLTAGE (300mV/DIV) 121 118 117 116 -40 25 85 VIN 0V 0V VOUT CH2 = 5V/DIV 02730-026 119 02730-023 PSRR (dB) 120 125 TEMPERATURE (C) TIME (4s/DIV) Figure 23. PSRR vs. Temperature Figure 26. Negative Overvoltage Recovery Rev. F | Page 9 of 24 AD8610/AD8620 100 PEAK-TO-PEAK VOLTAGE NOISE (1V/DIV) VS = 5V 90 VS = 13V VIN p-p = 1.8V 80 ZOUT () 70 60 GAIN = +1 50 40 30 GAIN = +100 GAIN = +10 02730-030 20 02730-027 10 0 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) TIME (1s/DIV) Figure 27. 0.1 Hz to 10 Hz Input Voltage Noise Figure 30. ZOUT vs. Frequency 3000 1000 2500 2000 IB (pA) 100 10 1500 1000 1 1 10 100 1k 10k 100k 02730-031 500 02730-028 VOLTAGE NOISE DENSITY (nV/ Hz) VS = 13V 0 1M 0 25 FREQUENCY (Hz) Figure 28. Input Voltage Noise Density vs. Frequency 100 40 50 40 GAIN = +100 GAIN = +10 20 10 10k 100k 1M 10M 100M FREQUENCY (Hz) 30 25 20 15 +OS -OS 10 5 0 02730-032 SMALL SIGNAL OVERSHOOT (%) GAIN = +1 02730-029 ZOUT () 70 0 1k VS = 13V RL = 2k VIN = 100mV p-p 35 80 30 125 Figure 31. Input Bias Current vs. Temperature VS = 13V 90 60 85 TEMPERATURE (C) 0 10 100 1k CAPACITANCE (pF) Figure 29. ZOUT vs. Frequency Figure 32. Small Signal Overshoot vs. Load Capacitance Rev. F | Page 10 of 24 10k AD8610/AD8620 40 VS = 5V RL = 2k VIN = 100mV SMALL SIGNAL OVERSHOOT (%) 35 30 20 15 +OS -OS 10 0 02730-033 5 VS = 13V VIN p-p = 20V AV = +1 RL = 2k CL = 20pF 0 10 100 1k 10k 02730-036 VOLTAGE (5V/DIV) 25 TIME (400ns/DIV) CAPACITANCE (pF) Figure 33. Small Signal Overshoot vs. Load Capacitance Figure 36. +Slew Rate at G = +1 VOLTAGE (5V/DIV) VIN VOUT TIME (400s/DIV) 02730-037 VS = 13V VIN p-p = 20V AV = +1 RL = 2k CL = 20pF 02730-034 VOLTAGE (5V/DIV) VS = 13V VIN = 14V AV = +1 FREQ = 0.5kHz TIME (400ns/DIV) Figure 34. No Phase Reversal Figure 37. -Slew Rate at G = +1 VS = 13V VIN p-p = 20V AV = +1 RL = 2k CL = 20pF 02730-038 02730-035 VOLTAGE (5V/DIV) VOLTAGE (5V/DIV) VS = 13V VIN p-p = 20V AV = -1 RL = 2k CL = 20pF TIME (1s/DIV) TIME (1s/DIV) Figure 35. Large Signal Response at G = +1 Figure 38. Large Signal Response at G = -1 Rev. F | Page 11 of 24 02730-040 VOLTAGE (5V/DIV) VS = 13V VIN p-p = 20V AV = -1 RL = 2k SR = 55V/s CL = 20pF VS = 13V VIN p-p = 20V AV = -1 RL = 2k SR = 50V/s CL = 20pF 02730-039 VOLTAGE (5V/DIV) AD8610/AD8620 TIME (400ns/DIV) TIME (400ns/DIV) Figure 39. +Slew Rate at G = -1 Figure 40. -Slew Rate at G = -1 Rev. F | Page 12 of 24 AD8610/AD8620 THEORY OF OPERATION 2 - -13V R2 2k V- V+ 5 R3 R4 2k 2k U2 136 6 7 134 132 CS (dB) VIN 20V p-p U1 V+ V- 138 02730-041 3 + R1 20k Figure 41. Channel Separation Test Circuit FUNCTIONAL DESCRIPTION 130 128 126 124 122 120 0 50 100 150 200 250 300 350 FREQUENCY (kHz) Figure 42. AD8620 Channel Separation Graph Power Consumption A major advantage of the AD8610/AD8620 in new designs is the power saving capability. Lower power consumption of the AD8610/AD8620 makes them 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 vs. the OPA627 in Figure 43. The unique input architecture of the AD8610/AD8620 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 85C. The gate current of a JFET doubles every 10C, resulting in a similar increase in input bias current over temperature. Give special care to the PC board layout to minimize leakage currents between PCB traces. Improper layout and board handling generates a leakage current that exceeds the bias current of the AD8610/AD8620. Rev. F | Page 13 of 24 8 7 SUPPLY CURRENT (mA) The AD8610/AD8620 are manufactured on the Analog Devices, Inc., XFCB (eXtra fast complementary bipolar) process. XFCB is fully dielectrically isolated (DI) and used in conjunction with N-channel JFET technology and thin film resistors (that can be trimmed) to create the JFET input amplifier. Dielectrically isolated NPN and PNP transistors fabricated on XFCB have an f > 3 GHz. Low TC thin film resistors enable very accurate offset voltage and offset voltage temperature coefficient trimming. These process breakthroughs allow Analog Devices 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/AD8620 are unconditionally stable in all gains, even with capacitive loads well in excess of 1 nF. The AD8610B grade achieves less than 100 V of offset and 1 V/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 surface-mount packages and is fully specified with supply voltages from 5.0 V to 13 V. The very wide specified temperature range, up to 125C, guarantees superior operation in systems with little or no active cooling. 02730-042 +13V OPA627 6 5 4 3 02730-043 CS (dB) = 20 log (VOUT / 10 x VIN) AD8610 2 -75 -50 -25 0 25 50 75 TEMPERATURE (C) Figure 43. Supply Current vs. Temperature 100 125 AD8610/AD8620 +5V 3 The AD8610/AD8620 have excellent capacitive load driving capability and can safely drive up to 10 nF when operating with a 5.0 V supply. Figure 44 and Figure 45 compare the AD8610/ AD8620 against the OPA627 in the noninverting gain configuration driving a 10 k 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/AD8620 have much less ringing than the OPA627 with heavy capacitive loads. 2 7 4 -5V 2k 2k 2F Figure 46. Capacitive Load Drive Test Circuit VOLTAGE (20mV/DIV) VOLTAGE (50mV/DIV) VS = 5V RL = 10k CL = 10,000pF VIN = 50mV 02730-046 Driving Large Capacitive Loads 02730-047 VS = 5V RL = 10k CL = 2F 02730-044 TIME (20s/DIV) Figure 47. OPA627 Capacitive Load Drive, AV = +2 TIME (2s/DIV) Figure 44. OPA627 Driving CL = 10,000 pF VOLTAGE (20mV/DIV) VOLTAGE (50mV/DIV) VS = 5V RL = 10k CL = 10,000pF 02730-048 VS = 5V RL = 10k CL = 2F 02730-045 TIME (20s/DIV) Figure 48. AD8610/AD8620 Capacitive Load Drive, AV = +2 TIME (2s/DIV) Figure 45. AD8610/AD8620 Driving CL = 10,000 pF The AD8610/AD8620 can drive much larger capacitances without any external compensation. Although the AD8610/ AD8620 are stable with very large capacitive loads, remember that this capacitive loading limits the bandwidth of the amplifier. Heavy capacitive loads also increase the amount of overshoot and ringing at the output. Figure 47 and Figure 48 show the AD8610/AD8620 and the OPA627 in a noninverting gain of +2 driving 2 F of capacitance load. The ringing on the OPA627 is much larger in magnitude and continues 10 times longer than the AD8610/AD8620. Rev. F | Page 14 of 24 AD8610/AD8620 Slew Rate (Unity Gain Inverting vs. Noninverting) VS = 13V RL = 2k G = -1 VOLTAGE (5V/DIV) Amplifiers generally have a faster slew rate in an inverting unity gain configuration due to the absence of the differential input capacitance. Figure 49 through Figure 52 show the performance of the AD8610/AD8620 configured in a unity gain of -1 compared to the OPA627. The AD8610/AD8620 slew rate is more symmetrical, and both the positive and negative transitions are much cleaner than in the OPA627. SR = 54V/s 02730-051 SR = 54V/s TIME (400ns/DIV) Figure 51. -Slew Rate of AD8610/AD8620 in Unity Gain of -1 VOLTAGE (5V/DIV) VS = 13V RL = 2k G = -1 02730-049 VOLTAGE (5V/DIV) VS = 13V RL = 2k G = -1 TIME (400ns/DIV) Figure 49. +Slew Rate of AD8610/AD8620 in Unity Gain of -1 SR = 56V/s 02730-052 TIME (400ns/DIV) SR = 42.1V/s Figure 52. -Slew Rate of OPA627 in Unity Gain of -1 02730-050 VOLTAGE (5V/DIV) VS = 13V RL = 2k G = -1 TIME (400ns/DIV) Figure 50. +Slew Rate of OPA627 in Unity Gain of -1 The AD8610/AD8620 have a very fast slew rate of 60 V/s even when configured in a noninverting gain of +1. This is the toughest condition to impose on any amplifier because the input commonmode 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, a voltage difference of about 2 V between the inputs must be ensured. This is required for virtually any JFET op amp so that one side of the op amp input circuit is completely off, thus maximizing the current available to charge and discharge the internal compensation capacitance. Lower differential drive voltages produce lower slew rate readings. A JFET input op amp with a slew rate of 60 V/s at unity gain with VIN = 10 V may slew at 20 V/s if it is operated at a gain of +100 with VIN = 100 mV. Rev. F | Page 15 of 24 AD8610/AD8620 The slew rate of the AD8610/AD8620 is double that of the OPA627 when configured in a unity gain of +1 (see Figure 53 and Figure 54). VOLTAGE (5V/DIV) VS = 13V RL = 2k G = +1 02730-053 SR = 85V/s TIME (400ns/DIV) Figure 53. +Slew Rate of AD8610/AD8620 in Unity Gain of +1 VOLTAGE (5V/DIV) VS = 13V RL = 2k G = +1 Input Overvoltage Protection When the input of an amplifier is driven below VEE or above VCC by more than one VBE, large currents flow from the substrate through the negative supply (V-) or the positive supply (V+), respectively, to the input pins and 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/AD8620 inputs to limit current to below damaging levels. Series resistance of 10 k generates less than 25 V of offset. This 10 k allows input voltages more than 5 V beyond either power supply. Thermal noise generated by the resistor adds 7.5 nV/Hz to the noise of the AD8610/AD8620. For the AD8610/ AD8620, differential voltages equal to the supply voltage do not cause any problems (see Figure 55). In this context, note 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 diodes greatly interfere with many application circuits, such as precision rectifiers and comparators. The AD8610/ AD8620 are free from these limitations. +13V 3 14V SR = 23V/s 0 2 7 4 6 AD8610 -13V 02730-056 V1 02730-054 Figure 56. Unity Gain Follower No Phase Reversal TIME (400ns/DIV) Figure 54. +Slew Rate 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 for a given distortion (for example, 1%) from the equation FPBW = SR (2 x 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 can cause permanent damage or no recoverable 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 are designed to prevent phase reversal when one or both inputs are forced beyond their input common-mode voltage range. CH1 = 20.8V p-p VIN VOLTAGE (5V/DIV) VOLTAGE (10V/DIV) 0V CH2 = 19.4V p-p VOUT 02730-057 02730-055 0V TIME (400ns/DIV) TIME (400s/DIV) Figure 55. AD8610 FPBW Figure 57. No Phase Reversal Rev. F | Page 16 of 24 AD8610/AD8620 THD Readings vs. Common-Mode Voltage Settling Time Total harmonic distortion of the AD8610/AD8620 is well below 0.0006% with any load down to 600 . The AD8610 outperforms the OPA627 for distortion, especially at frequencies above 20 kHz. The AD8610/AD8620 have a very fast settling time, even to a very tight error band, as can be seen from Figure 60. The AD8610/ AD8620 are configured in an inverting gain of +1 with 2 k input and feedback resistors. The output is monitored with a 10x, 10 M, 11.2 pF scope probe. 0.1 VS = 13V VIN = 5V rms BW = 80kHz 1.2k 1.0k SETTLING TIME (ns) OPA627 0.001 02730-058 AD8610 0.0001 10 100 1k 10k 800 600 400 200 02730-060 THD + N (%) 0.01 80k 0 0.001 FREQUENCY (Hz) 0.01 0.1 1 10 ERROR BAND (%) Figure 58. AD8610 vs. OPA627 THD + Noise @ VCM = 0 V Figure 60. AD8610/AD8620 Settling Time vs. Error Band 0.1 VS = 13V RL = 600 1.2k SETTLING TIME (ns) 2V rms 0.01 4V rms 6V rms 100 1k 10k 400 200 20k 0 0.001 FREQUENCY (Hz) Figure 59. THD + Noise vs. Frequency 0.01 0.1 1 ERROR BAND (%) Figure 61. OPA627 Settling Time vs. Error Band Noise vs. Common-Mode Voltage The AD8610/AD8620 noise density varies only 10% over the input range, as shown in Table 5. Table 5. Noise vs. Common-Mode Voltage VCM at f = 1 kHz (V) -10 -5 0 +5 +10 600 OPA627 02730-059 0.001 10 800 02730-061 THD + N (%) 1.0k Noise Reading (nV/Hz) 7.21 6.89 6.73 6.41 7.21 Rev. F | Page 17 of 24 10 AD8610/AD8620 10 3.0 ERROR BAND = 0.01% 2.0 1.5 1.0 02730-062 0 500 1000 1500 DELTA FROM RESPECTIVE RAIL (V) ERROR BAND = 0.01% SETTLING TIME (s) 2.5 2.0 1.5 1.0 0.1 1 02730-063 1500 VCC 1 0.1 0.00001 0.5 1000 0.01 10 3.0 500 0.001 Figure 64. AD8610/AD8620 Dropout from 13 V vs. Load Current 2000 CL (pF) 0 0.0001 LOAD CURRENT (A) Figure 62. AD8610/AD8620 Settling Time vs. Load Capacitance 0 VEE VCC 0.1 0.00001 0.5 0 1 VEE 02730-065 SETTLING TIME (s) 2.5 02730-064 DELTA FROM RESPECTIVE RAIL (V) The AD8610/AD8620 maintain this fast settling time when loaded with large capacitive loads, as shown in Figure 62. 0.0001 0.001 0.01 0.1 1 LOAD CURRENT (A) Figure 65. OPA627 Dropout from 15 V vs. Load Current 2000 CL (pF) Figure 63. OPA627 Settling Time vs. Load Capacitance Output Current Capability The AD8610/AD8620 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 supplies of 13 V. Figure 64 and Figure 65 compare the output voltage vs. load current of AD8610/ AD8620 and OPA627. Although operating conditions imposed on the AD8610/AD8620 (13 V) are less favorable than the OPA627 (15 V), it can be seen that the AD8610/AD8620 have much better drive capability (lower headroom to the supply) for a given load current. Operating with Supplies Greater than 13 V The AD8610/AD8620 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. Rev. F | Page 18 of 24 AD8610/AD8620 +5V Input Offset Voltage Adjustment 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 66 to further reduce the dc offset. By using resistors in the range of 50 k, offset trim range is 3.3 mV. 100 VIN 7 1 3 AD8610 2 10k 5pF AD8610 6 1 4 +5V VOUT R1 V- +5V 12 VL Y0 02730-066 5 -5V 1 G Figure 66. Offset Voltage Nulling Circuit Programmable Gain Amplifier (PGA) The combination of low noise, low input bias current, low input offset voltage, and low temperature drift make the AD8610/ AD8620 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 67. In Figure 67, when the 10 pA bias current of the AD8610 is dropped across the (<5 ) RON of the switch, it results in a negligible offset error. A A1 B S1 3 1k D1 2 10k G = +1 IN1 ADG452 S2 Y1 A0 13 VDD Y2 Y3 74HC139 16 9 8 14 G = +10 IN2 D2 15 S3 11 D3 10 S4 6 D4 7 1k G = +100 IN3 100 G = +1000 IN4 VSS 4 GND 11 5 -5V 02730-067 7 3 VOUT 4 V+ 2 6 5 Figure 67. High Precision PGA 1. Room temperature error calculation due to RON and IB VOS = IB x RON = 2 pA x 5 = 10 pV Total Offset = AD8610 (Offset) + VOS When high precision resistors are used, as in the circuit of Figure 67, the error introduced by the PGA is within the 1/2 LSB requirement for a 16-bit system. Total Offset = AD8610 (Offset_Trimmed) + VOS Total Offset = 5 V + 10 pV 5 V 2. Full temperature error calculation due to RON and IB VOS (@ 85C) = IB (@ 85C) x RON (@ 85C) = 250 pA x 15 = 3.75 nV 3. The temperature coefficient of switch and AD8610/AD8620 combined is essentially the same as the TCVOS of the AD8610/AD8620. VOS/T(total) = VOS/T(AD8610/AD8620) + VOS/T(IB x RON) VOS/T(total) = 0.5 V/C + 0.06 nV/C 0.5 V/C Rev. F | Page 19 of 24 AD8610/AD8620 High Speed Instrumentation Amplifier The 3-op-amp instrumentation amplifiers shown in Figure 68 can provide a range of gains from unity up to 1000 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+ 8 3 Second-Order, Low-Pass Filter 1/2 AD8620 1 U1 2 4 C5 V- 10pF V+ R1 1k 3 R4 2k At higher frequencies, the dynamic response of the amplifier must be carefully considered. In this case, slew rate, bandwidth, and open-loop gain play a major role in amplifier selection. The slew rate must be both fast and symmetrical to minimize distortion. The bandwidth of the amplifier, in conjunction with the gain of the filter, dictates the frequency response of the filter. The use of high performance amplifiers, such as the AD8610/AD8620, minimizes both dc and ac errors in all active filter applications. R7 2k C4 15pF AD8610 U2 2 RG R8 2k 7 6 VOUT R6 2k 4 Figure 69 shows the AD8610 configured as a second-order, Butterworth, low-pass filter. With the values as shown, the design corner was 1 MHz, and the bench measurement was 974 kHz. The wide bandwidth of the AD8610/AD8620 allows corner frequencies into the megahertz range, but the input capacitances should be taken into account by making C1 and C2 smaller than the calculated values. The following equations can be used for component selection: R1 = R2 = User Selected (Typical Values = 10 k to 100 k) V- R5 2k +INB 5 1/2 AD8620 6 7 C3 15pF U1 1.414 C1 = (2 )( f CUTOFF )(R1) C2 = (2 )( f CUTOFF )(R1) 0.707 where C1 and C2 are in farads. R2 1k 02730-068 +13V C2 10pF VIN Figure 68. High Speed Instrumentation Amplifier High Speed Filters R2 R1 1020 1020 7 5 3 C2 110pF AD8610 U1 2 The four most popular configurations are Butterworth, Elliptical, Bessel (Thompson), and Chebyshev. Each type has a response that is optimized for a given characteristic, as shown in Table 6. C1 220pF 6 VOUT 1 4 -13V Figure 69. Second-Order, Low-Pass Filter Table 6. Filter Types Type Butterworth Chebyshev Elliptical Bessel (Thompson) Sensitivity Moderate Good Best Poor Overshoot Good Moderate Poor Best Rev. F | Page 20 of 24 Phase Nonlinear Linear Amplitude (Pass Band) Maximum flat Equal ripple Equal ripple 02730-069 +INA In active filter applications using operational amplifiers, the dc accuracy of the amplifier is critical to optimal filter performance. The offset voltage and bias current of the amplifier contribute to output error. Input offset voltage is passed by the filter and can be amplified to produce excessive output offset. For low frequency applications requiring large value input resistors, bias and offset currents flowing through these resistors also generate an offset voltage. AD8610/AD8620 High Speed, Low Noise Differential Driver Rev. F | Page 21 of 24 V+ 3 V+ 3 6 2 R4 1k AD8610 V- R3 1k 1 R8 1k 0 R9 1k 2 R10 1/2 AD8620 50 U2 V- 5 R7 1k R11 50 7 R5 1k R6 10k R12 1k R1 1k V+ 6 VO1 R13 1k VO2 1/2 AD8620 V- U3 R2 1k Figure 70. Differential Driver VO2 - VO1 = VIN 0 02730-070 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 70 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 k 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-to-input noise voltage spectral density of 6 nV/Hz. The design is a balanced transmission system without transformers, 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. AD8610/AD8620 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 3.20 3.00 2.80 1 5 4.00 (0.1574) 3.80 (0.1497) 5.15 4.90 4.65 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 0.65 BSC 0.95 0.85 0.75 1.10 MAX 0.38 0.22 COPLANARITY 0.10 6.20 (0.2441) 5.80 (0.2284) 4 PIN 1 0.15 0.00 8 1 0.23 0.08 8 0 0.80 0.60 0.40 SEATING PLANE COPLANARITY 0.10 SEATING PLANE 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) 0.50 (0.0196) 0.25 (0.0099) 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-012-A A 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-187-AA Figure 71. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters Figure 72. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) ORDERING GUIDE Model AD8610AR AD8610AR-REEL AD8610AR-REEL7 AD8610ARZ1 AD8610ARZ-REEL1 AD8610ARZ-REEL71 AD8610ARM-REEL AD8610ARM-R2 AD8610ARMZ-REEL1 AD8610ARMZ-R21 AD8610BR AD8610BR-REEL AD8610BR-REEL7 AD8610BRZ1 AD8610BRZ-REEL1 AD8610BRZ-REEL71 AD8620AR AD8620AR-REEL AD8620AR-REEL7 AD8620ARZ1 AD8620ARZ-REEL1 AD8620ARZ-REEL71 AD8620BR AD8620BR-REEL AD8620BR-REEL7 AD8620BRZ1 AD8620BRZ-REEL1 AD8620BRZ-REEL71 1 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package Description 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N Z = RoHS Compliant Part, # denotes RoHs-compliant product can be top or bottom marked. Rev. F | Page 22 of 24 45 Package Option R-8 R-8 R-8 R-8 R-8 R-8 RM-8 RM-8 RM-8 RM-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 Branding B0A B0A B0A# B0A# 012407-A 8 3.20 3.00 2.80 AD8610/AD8620 NOTES Rev. F | Page 23 of 24 AD8610/AD8620 NOTES (c)2001-2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D02730-0-5/08(F) Rev. F | Page 24 of 24