Datasheet AD8610, AD8620 Datasheet (ANALOG DEVICES)

Precision, Very Low Noise,
Low Input Bias Current, Wide
Bandwidth JFET Operational Amplifiers

FEATURES

Low noise: 6 nV/√Hz Low offset voltage: 100 μV 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

APPLICATIONS

Photodiode amplifiers AT E Instrumentation Sensors and controls High performance filters Fast precision integrators High performance audio

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 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 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.
AD8610/AD8620

PIN CONFIGURATIONS

NULL
1
–IN
2
AD8610
+IN
3
TOP VIEW
(Not to Scale)
4
V–
NC = NO CONNECT
Figure 1. 8-Lead MSOP and 8-Lead SOIC_N
OUTA
1
–INA
2
AD8620
3
+INA
TOP VIEW
(Not to Scale)
4
V–
Figure 2. 8-Lead SOIC_N
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 (−40°C to +125°C). 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.
8 7 6 5
8 7 6 5
NC V+ OUT NULL
V+ OUTB –INB +INB
02730-001
2730-002
Rev. F
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 ©2001–2008 Analog Devices, Inc. All rights reserved.
AD8610/AD8620

TABLE OF CONTENTS

Features .............................................................................................. 1
Applications ....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Electrical Specifications ............................................................... 4

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.
Absolute Maximum Ratings ............................................................5
ESD Caution...................................................................................5
Typical Performance Characteristics ..............................................6
Theory of Operation ...................................................................... 13
Functional Description .............................................................. 13
Outline Dimensions ....................................................................... 22
Ordering Guide .......................................................................... 22
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 = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage (AD8610B) VOS 45 100 μV
−40°C < TA < +125°C 80 200 μV Offset Voltage (AD8620B) VOS 45 150 μV
−40°C < TA < +125°C 80 300 μV Offset Voltage (AD8610A/AD8620A) VOS 85 250 μV 25°C < TA < 125°C 90 350 μV
−40°C < TA < +125°C 150 850 μV Input Bias Current IB −10 +2 +10 pA
−40°C < TA < +85°C −250 +130 +250 pA
−40°C < TA < +125°C −2.5 +1.5 +2.5 nA Input Offset Current IOS −10 +1 +10 pA
−40°C < TA < +85°C −75 +20 +75 pA
−40°C < TA < +125°C −150 +40 +150 pA Input Voltage Range −2 +3 V Common-Mode Rejection Ratio CMRR VCM = –1.5 V to +2.5 V 90 95 dB Large Signal Voltage Gain AVO RL = 1 kΩ, VO = −3 V to +3 V 100 180 V/mV Offset Voltage Drift (AD8610B) ΔVOS/ΔT −40°C < TA < +125°C 0.5 1 μV/°C Offset Voltage Drift (AD8620B) ΔVOS/ΔT −40°C < TA < +125°C 0.5 1.5 μV/°C Offset Voltage Drift (AD8610A/AD8620A) ΔVOS/ΔT −40°C < TA < +125°C 0.8 3.5 μV/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH RL = 1 kΩ, −40°C < TA < +125°C 3.8 4 V Output Voltage Low VOL RL = 1 kΩ, −40°C < TA < +125°C −4 −3.8 V Output Current I
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = ±5 V to ±13 V 100 110 dB Supply Current per Amplifier ISY VO = 0 V 2.5 3.0 mA
−40°C < TA < +125°C 3.0 3.5 mA DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 40 50 V/μs Gain Bandwidth Product GBP 25 MHz Settling Time tS AV = +1, 4 V step, to 0.01% 350 ns
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 1.8 μV p-p Voltage Noise Density en f = 1 kHz 6 nV/√Hz Current Noise Density in f = 1 kHz 5 fA/√Hz Input Capacitance CIN
Differential Mode 8 pF Common Mode 15 pF
Channel Separation CS
f = 10 kHz 137 dB f = 300 kHz 120 dB
V
OUT
> ±2 V ±30 mA
OUT
Rev. F | Page 3 of 24
AD8610/AD8620

ELECTRICAL SPECIFICATIONS

@ VS = ±13 V, VCM = 0 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage (AD8610B) VOS 45 100 μV
−40°C < TA < +125°C 80 200 μV Offset Voltage (AD8620B) VOS 45 150 μV
−40°C < TA < +125°C 80 300 μV Offset Voltage (AD8610A/AD8620A) VOS 85 250 μV 25°C < TA < 125°C 90 350 μV
−40°C < TA < +125°C 150 850 μV Input Bias Current IB −10 +3 +10 pA
−40°C < TA < +85°C −250 +130 +250 pA
−40°C < TA < +125°C −3.5 +3.5 nA Input Offset Current IOS −10 +1.5 +10 pA
−40°C < TA < +85°C −75 +20 +75 pA
−40°C < TA < +125°C −150 +40 +150 pA Input Voltage Range −10.5 +10.5 V Common-Mode Rejection Ratio CMRR VCM = −10 V to +10 V 90 110 dB Large Signal Voltage Gain AVO RL = 1 kΩ, VO = −10 V to +10 V 100 200 V/mV Offset Voltage Drift (AD8610B) ΔVOS/ΔT −40°C < TA < +125°C 0.5 1 μV/°C Offset Voltage Drift (AD8620B) ΔVOS/ΔT −40°C < TA < +125°C 0.5 1.5 μV/°C Offset Voltage Drift (AD8610A/AD8620A) ΔVOS/ΔT −40°C < TA < +125°C 0.8 3.5 μV/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH RL = 1 kΩ, −40°C < TA < +125°C +11.75 +11.84 V Output Voltage Low VOL RL = 1 kΩ, −40°C < TA < +125°C −11.84 −11.75 V Output Current I Short-Circuit Current ISC
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = ±5 V to ±13 V 100 110 dB Supply Current per Amplifier ISY VO = 0 V 3.0 3.5 mA
−40°C < TA < +125°C 3.5 4.0 mA DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 40 60 V/μs Gain Bandwidth Product GBP 25 MHz Settling Time tS AV = +1, 10 V step, to 0.01% 600 ns
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 1.8 μV p-p Voltage Noise Density en f = 1 kHz 6 nV/√Hz Current Noise Density in f = 1 kHz 5 fA/√Hz Input Capacitance CIN
Differential Mode 8 pF Common Mode 15 pF
Channel Separation CS
f = 10 kHz 137 dB f = 300 kHz 120 dB
V
OUT
> 10 V ±45 mA
OUT
±65 mA
Rev. F | Page 4 of 24
AD8610/AD8620

ABSOLUTE MAXIMUM RATINGS

Table 3.
Parameter Rating
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 –65°C to +150°C Operating Temperature Range –40°C to +125°C Junction Temperature Range –65°C to +150°C Lead Temperature (Soldering, 10 sec) 300°C
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 θ
8-Lead MSOP (RM) 190 44 °C/W 8-Lead SOIC (R) 158 43 °C/W
1
θJA is specified for worst-case conditions, that is, θJA is specified for a device
soldered in circuit board for surface-mount packages.
1
θ
JA
Unit
JC

ESD CAUTION

Rev. F | Page 5 of 24
AD8610/AD8620

TYPICAL PERFORMANCE CHARACTERISTICS

14
VS = ±13V
12
600
VS = ±5V
400
10
8
6
4
NUMBER OF AMPLIFIERS
2
0
–250 –150 –50 50 150 250
INPUT OFFSET VOLTAGE (µV)
Figure 3. Input Offset Voltage
600
400
200
0
–200
INPUT OFFSET VOLTAGE (µV)
–400
VS = ±13V
200
0
–200
INPUT OFFSET VOLTAGE (µV)
–400
02730-003
–600
–40 25 85 125
TEMPERATURE (°C)
02730-006
Figure 6. Input Offset Voltage vs. Temperature at ±5 V (300 Amplifiers)
14
12
10
8
6
4
NUMBER OF AMPLIFIERS
2
V
= ±5V OR ±13V
S
–600
–40 25 85 125
TEMPERATURE (° C)
Figure 4. Input Offset Voltage vs. Temperature at ±13 V (300 Amplifiers)
18
16
14
12
10
8
6
NUMBER OF AMPL IFIERS
4
2
0
–250 –150 –50 50 150 250
INPUT OFFSET VOLTAGE (µV)
VS = ±5V
02730-005
Figure 5. Input Offset Voltage
02730-004
Rev. F | Page 6 of 24
0
0 0.2 0.6 1.0 1.4 1.8 2.2 2.6
TCVOS (µV/°C)
Figure 7. Input Offset Voltage Drift
3.6
3.4
3.2
3.0
2.8
2.6
2.4
INPUT BIAS CURRENT (pA)
2.2
2.0
COMMON-MODE VOLTAGE (V)
Figure 8. Input Bias Current vs. Common-Mode Voltage
V
S
= ±13V
02730-007
02730-008
10–10 5–5 0
AD8610/AD8620
3.0
2.5
2.0
1.5
1.0
SUPPLY CURRENT (mA)
0.5
0
0321 4 5 6 7 8 9 10 11 12 13
SUPPLY VOLTAGE (±V)
Figure 9. Supply Current vs. Supply Voltage
02730-009
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
OUTPUT VO LTAGE T O SUPPLY RAI L (V)
0
100 10k 100k1k 1M 10M 100M
RESISTANCE LOAD (Ω)
VS= ±13V
Figure 12. Output Voltage to Supply Rail vs. Resistance Load
02730-012
3.05
VS = ±13V
2.95
2.85
2.75
SUPPLY CURRENT (mA)
2.65
2.55 –40 1258525
TEMPERATURE ( °C)
02730-010
Figure 10. Supply Current vs. Temperature
2.65
VS = ±5V
2.60
2.55
2.50
2.45
4.25
4.20
4.15
4.10
4.05
OUTPUT VO LTAGE HI GH (V)
4.00
3.95
VS= ±5V
= 1k
R
L
25 85–40 125
TEMPERATURE ( °C)
Figure 13. Output Voltage High vs. Temperature
3.95
–4.00
–4.05
–4.10
–4.15
VS= ±5V
= 1k
R
L
02730-013
2.40
SUPPLY CURRENT (mA)
2.35
2.30 –40 1258525
TEMPERATURE ( °C)
02730-011
Figure 11. Supply Current vs. Temperature
–4.20
OUTPUT VOLTAGE LOW (V)
–4.25
–4.30
25 85–40 125
TEMPERATURE ( °C)
Figure 14. Output Voltage Low vs. Temperature
02730-014
Rev. F | Page 7 of 24
AD8610/AD8620
12.05
12.00
VS= ±13V
= 1k
R
L
60
40
G = +100
VS= ±13V R
= 2k
L
C
= 20pF
L
11.95
11.90
OUTPUT VO LTAGE HI GH (V)
11.85
11.80 25 85–40 125
TEMPERATURE ( °C)
Figure 15. Output Voltage High vs. Temperature
11.80
–11.85
–11.90
–11.95
OUTPUT VO LTAGE L OW (V)
–12.00
–12.05
25 85–40 125
TEMPERATURE ( °C)
Figure 16. Output Voltage Low vs. Temperature
VS= ±13V
= 1k
R
L
20
0
CLOSED-LOOP GAIN (dB)
–20
02730-015
–40
1k 10k 100k 1M 10M 100M
G = +10
G = +1
02730-018
FREQUENCY (Hz)
Figure 18. Closed-Loop Gain vs. Frequency
260
VS= ±13V V
240
220
200
180
(V/mV)
VO
A
160
140
120
02730-016
100
–40 25 85 125
TEMPERATURE (°C)
O
R
L
= ±10V = 1k
02730-019
Figure 19. AVO vs. Temperature
120
100
80
60
40
AD8610
20
V
= ±13V
S
C
= 20pF
L
0
GAIN AND PHASE (d B AND DEGREES)
–20
1kHz 10kHz 100kHz 1MHz 10MHz 50MHz
FREQUENCY
Figure 17. Open-Loop Gain and Phase vs. Frequency
02730-017
Rev. F | Page 8 of 24
190
180
170
160
150
(V/mV)
140
VO
A
130
120
110
100
–40 25 85 125
TEMPERATURE (°C)
VS= ±5V V
= ±3V
O
R
= 1k
L
02730-020
Figure 20. AVO vs. Temperature
AD8610/AD8620
160
140
120
100
80
–PSRR
60
PSRR (dB)
40
20
0
–20
–40
100 10k 100k1k 1M 10M 60M
FREQUENCY (Hz)
+PSRR
Figure 21. PSRR vs. Frequency
VS= ±13V
02730-021
140
120
100
80
60
CMRR (dB)
40
20
0
10 100 10k 100k1k 1M 10M 60M
FREQUENCY (Hz)
Figure 24. CMRR vs. Frequency
VS= ±13V
02730-024
160
140
120
100
80
–PSRR
60
PSRR (dB)
40
20
0
–20
–40
100 10k 100k1k 1M 10M 60M
FREQUENCY (Hz)
+PSRR
Figure 22. PSRR vs. Frequency
122
121
120
119
PSRR (dB)
118
117
116
25 85–40 125
TEMPERATURE (° C)
Figure 23. PSRR vs. Temperature
VS= ±5V
VS = ±13V V
= –300mV p-p
IN
A
= –100
V
R
= 10k
L
0V
VOLTAGE (300mV/DIV)
02730-022
CH2 = 5V/DIV
0V
TIME (4µs/DIV)
V
IN
V
OUT
02730-025
Figure 25. Positive Overvoltage Recovery
VS = ±13V V
= 300mV p-p
IN
A
= –100
V
R
= 10k
L
C
= 0pF
L
V
0V
VOLTAG E (300mV/DIV)
CH2 = 5V/DIV
02730-023
TIME (4µs/DIV)
IN
0V
V
OUT
02730-026
Figure 26. Negative Overvoltage Recovery
Rev. F | Page 9 of 24
AD8610/AD8620
PEAK-TO-PEAK VOLTAGE NOISE (1µV/DIV)
TIME (1s/ DIV)
Figure 27. 0.1 Hz to 10 Hz Input Voltage Noise
1000
100
10
VS = ±13V V
p-p = 1.8µV
IN
VS= ±13V
100
90
80
70
60
()
50
OUT
Z
40
30
20
10
02730-027
0
GAIN = +100
10k 100k1k 100M10M1M
Figure 30. Z
3000
2500
2000
1500
(pA)
B
I
1000
GAIN = +10
FREQUENCY (Hz)
vs. Frequency
OUT
VS= ±5V
GAIN = +1
02730-030
VOLTAGE NOISE DENSITY (nV/ Hz)
1
1 10 100 10k 100k1k 1M
FREQUENCY (Hz)
Figure 28. Input Voltage Noise Density vs. Frequency
100
90
80
70
60
()
50
OUT
Z
40
30
20
10
0
GAIN = +100
10k 100k1k 100M10M1M
Figure 29. Z
FREQUENCY (Hz)
vs. Frequency
OUT
GAIN = +1
GAIN = +10
VS= ±13V
500
02730-028
0
025 12585
TEMPERATURE ( °C)
02730-031
Figure 31. Input Bias Current vs. Temperature
40
VS = ±13V R
= 2k
35
L
V
= 100mV p-p
IN
30
25
20
15
10
SMALL SIGNAL OVERSHOOT (%)
5
02730-029
0
0 10 100 10k1k
CAPACITANCE (pF )
+OS
–OS
02730-032
Figure 32. Small Signal Overshoot vs. Load Capacitance
Rev. F | Page 10 of 24
AD8610/AD8620
40
VS = ±5V R
= 2k
35
L
V
= 100mV
IN
30
25
20
15
+OS
–OS
10
SMALL SIGNAL O VERSHOOT (%)
5
0
0 10 100 10k1k
CAPACITANCE (pF )
Figure 33. Small Signal Overshoot vs. Load Capacitance
VS = ±13V V A FREQ = 0. 5kHz
V
IN
VOLTAGE (5V/DIV)
V
OUT
TIME ( 400µs/DIV)
Figure 34. No Phase Reversal
= ±14V
IN
= +1
V
VOLTAGE (5V/DIV)
02730-033
VS = ±13V V
p-p = 20V
IN
A
= +1
V
R
= 2k
L
C
= 20pF
L
02730-036
TIME (400n s/DIV)
Figure 36. +Slew Rate at G = +1
VOLTAGE (5V/DIV)
VS = ±13V V
p-p = 20V
IN
A
= +1
V
R
= 2k
L
C
= 20pF
02730-034
L
02730-037
TIME (400n s/DIV)
Figure 37. –Slew Rate at G = +1
VOLTAGE (5V/DIV)
TIME (1µs/DIV)
Figure 35. Large Signal Response at G = +1
VS = ±13V V
p-p = 20V
IN
A
= +1
V
R
= 2k
L
C
= 20pF
L
02730-035
Rev. F | Page 11 of 24
VS = ±13V V
p-p = 20V
IN
A
= –1
V
R
= 2k
L
C
= 20pF
L
VOLTAGE (5V/DIV)
TIME (1µs/DIV)
Figure 38. Large Signal Response at G = −1
02730-038
AD8610/AD8620
VS = ±13V V
p-p = 20V
IN
A
= –1
V
R
= 2k
L
SR = 50V/µs C
= 20pF
L
VOLTAGE (5V/DIV)
TIME (400n s/DIV)
VS = ±13V V
p-p = 20V
IN
A
= –1
V
R
= 2k
L
SR = 55V/µs C
= 20pF
L
02730-039
Figure 39. +Slew Rate at G = −1
VOLTAGE (5V/DIV)
02730-040
TIME (400ns/DIV)
Figure 40. –Slew Rate at G = −1
Rev. F | Page 12 of 24
AD8610/AD8620
2
p

THEORY OF OPERATION

R4 2k
5
R3 2k
R1
20k
V– V+
R2
2k
6 7
U2
2730-041
> 3 GHz.
τ
CS (dB) = 20 log (V
+
V
IN
0V p-
3
2
+13V
V+ V–
–13V
OUT
U1
/ 10 × VIN)
Figure 41. Channel Separation Test Circuit

FUNCTIONAL DESCRIPTION

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 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 125°C, guarantees superior operation in systems with little or no active cooling.
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 85°C. The gate current of a JFET doubles every 10°C, 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.
138
136
134
132
130
128
CS (dB)
126
124
122
120
0 100 150 20050 250 300 350
FREQUENCY (kHz)
02730-042
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.
8
7
6
5
4
SUPPLY CURRENT (mA)
3
2
–75 –25 0 25–50 50 75 100 125
OPA627
AD8610
TEMPERATURE ( °C)
02730-043
Figure 43. Supply Current vs. Temperature
Rev. F | Page 13 of 24
AD8610/AD8620
V

Driving Large Capacitive Loads

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.
VS = ±5V R
= 10k
L
C
= 10,000pF
L
VOLTAGE (20mV/DIV)
02730-044
TIME (2µs/DIV)
Figure 44. OPA627 Driving C
= 10,000 pF
L
+5
3
VIN = 50mV
2k 2k
7
2
4
–5V
Figure 46. Capacitive Load Drive Test Circuit
VOLTAGE (50mV/DIV)
VS = ±5V R
= 10k
L
C
= 2µF
L
TIME (20µ s/DIV)
Figure 47. OPA627 Capacitive Load Drive, A
2µF
= +2
V
02730-046
02730-047
VS = ±5V R
= 10k
L
C
= 10,000pF
L
VOLTAGE (20mV/DIV)
02730-045
TIME (2µs/DIV)
Figure 45. AD8610/AD8620 Driving C
= 10,000 pF
L
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.
VOLTAGE (50mV/DIV)
VS = ±5V R
= 10k
L
C
= 2µF
L
TIME (20µ s/DIV)
Figure 48. AD8610/AD8620 Capacitive Load Drive, A
= +2
V
02730-048
Rev. F | Page 14 of 24
AD8610/AD8620

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. 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.
VS = ±13V R
= 2k
L
G= –1
SR = 54V/µs
VOLTAGE (5V/ DIV)
02730-049
TIME (400n s/DIV)
Figure 49. +Slew Rate of AD8610/AD8620 in Unity Gain of –1
SR = 54V/µs
VOLTAGE (5V/DIV)
TIME (400n s/DIV)
Figure 51. –Slew Rate of AD8610/AD8620 in Unity Gain of –1
SR = 56V/µs
VOLTAGE (5V/ DIV)
VS = ±13V R
= 2k
L
G= –1
VS = ±13V R
= 2k
L
G= –1
02730-051
SR = 42.1V/ µs
VOLTAGE (5V/DIV)
TIME (400n s/DIV)
Figure 50. +Slew Rate of OPA627 in Unity Gain of –1
VS = ±13V R
= 2k
L
G= –1
02730-052
TIME (4 00ns/DIV)
Figure 52. –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
02730-050
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 V 20 V/s if it is operated at a gain of +100 with V
= 10 V may slew at
IN
= 100 mV.
IN
Rev. F | Page 15 of 24
AD8610/AD8620
V
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).
VS = ±13V R
= 2k
L
G= +1
VOLTAGE (5V/DIV)
SR = 85V/µs
TIME (400n s/DIV)
02730-053
Figure 53. +Slew Rate of AD8610/AD8620 in Unity Gain of +1
VS = ±13V R
= 2k
L
G= +1
VOLTAGE (5V/ DIV)
SR = 23V/µs
TIME (400n s/DIV)
02730-054
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×π=
SR
()
2
CH1 = 20.8V p-p
V
PEAK

Input Overvoltage Protection

When the input of an amplifier is driven below VEE or above VCC by more than one V
, large currents flow from the substrate
BE
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.
+13
3
7
14V
V1
0
2
–13V
6
4
AD8610
02730-056
Figure 56. Unity Gain Follower

No Phase Reversal

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.
V
0V
VOLTAGE (10V/DIV)
0V
CH2 = 19.4V p-p
Figure 55. AD8610 FPBW
TIME (400ns/DIV)
VOLTAGE (5V/ DIV)
02730-055
TIME ( 400µs/DIV)
IN
V
OUT
02730-057
Figure 57. No Phase Reversal
Rev. F | Page 16 of 24
AD8610/AD8620

THD Readings vs. Common-Mode Voltage

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.
0.1
0.01
THD + N (%)
0.001
VS = ±13V V
= 5V rms
IN
BW = 80kHz
OPA627
AD8610

Settling Time

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 10×, 10 M, 11.2 pF scope probe.
1.2k
1.0k
800
600
400
SETTLING TIME (ns)
0.0001 10 100 1k 10k 80k
Figure 58. AD8610 vs. OPA627 THD + Noise @ V
0.1 VS = ±13V
= 600
R
L
0.01
THD + N (%)
0.001
4V rms
10 100 1k 10k 20k
FREQUENCY (Hz)
2V rms
6V rms
FREQUENCY (Hz)
CM
= 0 V
Figure 59. THD + Noise vs. Frequency

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) Noise Reading (nV/√Hz)
−10 7.21
−5 6.89 0 6.73 +5 6.41 +10 7.21
02730-058
200
0
0.001 0.01 0.1 1 10
ERROR BAND (%)
02730-060
Figure 60. AD8610/AD8620 Settling Time vs. Error Band
1.2k
1.0k
800
600
400
SETTLING T IME (ns)
OPA627
02730-059
200
0
0.001 0.01 0.1 1 10
ERROR BAND (%)
02730-061
Figure 61. OPA627 Settling Time vs. Error Band
Rev. F | Page 17 of 24
AD8610/AD8620
The AD8610/AD8620 maintain this fast settling time when loaded with large capacitive loads, as shown in Figure 62.
3.0
ERROR BAND = ±0.01%
2.5
2.0
1.5
1.0
SETTLING TIME (µs)
0.5
0
0 500 1000 1500 2000
Figure 62. AD8610/AD8620 Settling Time vs. Load Capacitance
3.0
ERROR BAND = ±0.01%
2.5
2.0
CL (pF)
10
1
V
EE
V
CC
DELTA FROM RESPECTIVE RAIL (V)
0.1
0.00001 0. 0001 0.001 0.01 0.1 1
02730-062
Figure 64. AD8610/AD8620 Dropout from ±13 V vs. Load Current
10
1
LOAD CURRENT (A)
V
CC
V
EE
02730-064
1.5
1.0
SETTLING TIME (µs)
0.5
0
0 500 1000 1500 2000
CL (pF)
02730-063
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.
DELTA FROM RESPECTIVE RAIL (V)
0.1
0.00001 0. 0001 0.001 0.01 0.1 1
LOAD CURRENT (A)
02730-065
Figure 65. OPA627 Dropout from ±15 V vs. Load Current
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
V
V

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.
+
7
2
AD8610
3
4
V–
6
1
5
R1
V
OUT
02730-066
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 I
currents
B
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 ) R
of the switch, it results in a
ON
negligible offset error. When high precision resistors are used, as in the circuit of
Figure 67, the error introduced by the PGA is within the ½ LSB requirement for a 16-bit system.
+5
3
2
V
LVDD
IN1
ADG452
IN2
IN3
IN4
V
SS
4
–5V
7
1
AD8610
5
4
–5V
+5V+5V
1312
GND
5
6
3
S1
2
D1
14
S2
15
D2
11
S3
10
D3
6
S4
7
D4
10k
1k
10k
1k
100
11
V
OUT
G = +1
G = +10
G = +100
G = +1000
02730-067
A
A
0
1
V
IN
Y
G
Y
A
B
Y
Y
74HC139
100
5pF
1
0
16
1
9
2
8
3
Figure 67. High Precision PGA
1. Room temperature error calculation due to RON and IB
ΔV
= IB × RON = 2 pA × 5  = 10 pV
OS
Total Offset = AD8610 (Offset) + ΔV Total Offset = AD8610 (Offset_Trimmed) + ΔV
OS
OS
Total Offset = 5 µV + 10 pV ≈ 5 µV
2. Full temperature error calculation due to R (@ 85°C) = IB (@ 85°C) × RON (@ 85°C) =
ΔV
OS
and IB
ON
250 pA × 15  = 3.75 nV
3. The temperature coefficient of switch and AD8610/AD8620
combined is essentially the same as the T
CVOS
of the
AD8610/AD8620.
V
/T(total) = VOS/ΔT(AD8610/AD8620) +
OS
V
/T(IB × RON)
OS
V
/ΔT(total) = 0.5 µV/°C + 0.06 nV/°C ≈ 0.5 µV/°C
OS
Rev. F | Page 19 of 24
AD8610/AD8620
V

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.
+
8
RG
3
1/2 AD8620
U1
2
4
V–
R4
R7
2k
2k
R8
2k
5
1/2 AD8620
U1
6
R2
1k
C2
10pF
C5
10pF
R1
1k
1
V+
7
3
C4 15pF
7
AD8610
2
U2
4
V–
R5
2k
C3
15pF
V
R6 2k
OUT
02730-068
6
+INA
+INB
Figure 68. High Speed Instrumentation Amplifier

High Speed Filters

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.
Table 6. Filter Types
Type Sensitivity Overshoot Phase Amplitude (Pass Band)
Butterworth Moderate Good Maximum flat Chebyshev Good Moderate Nonlinear Equal ripple Elliptical Best Poor Equal ripple Bessel (Thompson) Poor Best Linear
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.
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.

Second-Order, Low-Pass Filter

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)
C1
C2
=
()
=
414.1
()
π
2
CUTOFF
707.0
()
()
π
2
CUTOFF
()
R1f
()
R1f
where C1 and C2 are in farads.
+13V
C1
R2
1020R11020
V
IN
110p F
C2
Figure 69. Second-Order, Low-Pass Filter
7
3
AD8610
2
4
–13V
220pF
5
6
V
U1
1
OUT
02730-069
Rev. F | Page 20 of 24
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 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.
V+
3
3
2
V+
6
AD8610
V–
1k
1k
R4
R8 1k
0
R9 1k
R3
2
5
6
1
1/2 AD8620
U2
V–
R1
1k
V+
7
1/2 AD8620
U3
V–
R2
1k
R10
R13
50
1k
R12
1k
R11 50
VO2 – VO1 = V
0
R5 1k
R6 10k
R7 1k
IN
V
VO2
1
O
02730-070
Figure 70. Differential Driver
Rev. F | Page 21 of 24
AD8610/AD8620

OUTLINE DIMENSIONS

3.20
3.00
2.80
8
5
4
SEATING PLANE
5.15
4.90
4.65
1.10 MAX
0.23
0.08
8° 0°
3.20
3.00
1
2.80
PIN 1
0.65 BSC
0.95
0.85
0.75
0.15
0.38
0.00
0.22
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 71. 8-Lead Mini Small Outline Package [MSOP]
0.80
0.60
0.40
4.00 (0.1574)
3.80 (0.1497)
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
0.10
CONTROLL ING DIMENSI ONS ARE IN MILLIMETERS; INCH DI MENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRI ATE FOR USE IN DESIGN.
Figure 72. 8-Lead Standard Small Outline Package [SOIC_N]
(RM-8)
Dimensions shown in millimeters

ORDERING GUIDE

Model Temperature Range Package Description Package Option Branding
AD8610AR −40°C to +125°C 8-Lead SOIC_N R-8 AD8610AR-REEL −40°C to +125°C 8-Lead SOIC_N R-8 AD8610AR-REEL7 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610ARZ1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610ARZ-REEL1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610ARZ-REEL71 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610ARM-REEL −40°C to +125°C 8-Lead MSOP RM-8 B0A AD8610ARM-R2 −40°C to +125°C 8-Lead MSOP RM-8 B0A AD8610ARMZ-REEL1 −40°C to +125°C 8-Lead MSOP RM-8 B0A# AD8610ARMZ-R21 −40°C to +125°C 8-Lead MSOP RM-8 B0A# AD8610BR −40°C to +125°C 8-Lead SOIC_N R-8 AD8610BR-REEL −40°C to +125°C 8-Lead SOIC_N R-8 AD8610BR-REEL7 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610BRZ1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610BRZ-REEL1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8610BRZ-REEL71 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620AR −40°C to +125°C 8-Lead SOIC_N R-8 AD8620AR-REEL −40°C to +125°C 8-Lead SOIC_N R-8 AD8620AR-REEL7 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620ARZ1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620ARZ-REEL1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620ARZ-REEL71 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620BR −40°C to +125°C 8-Lead SOIC_N R-8 AD8620BR-REEL −40°C to +125°C 8-Lead SOIC_N R-8 AD8620BR-REEL7 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620BRZ1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620BRZ-REEL1 −40°C to +125°C 8-Lead SOIC_N R-8 AD8620BRZ-REEL71 −40°C to +125°C 8-Lead SOIC_N R-8
1
Z = RoHS Compliant Part, # denotes RoHs-compliant product can be top or bottom marked.
5.00 (0.1968)
4.80 (0.1890)
85
1
1.27 (0.0500)
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MS-012-A A
BSC
6.20 (0.2441)
5.80 (0.2284)
4
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.31 (0.0122)
8° 0°
0.25 (0.0098)
0.17 (0.0067)
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
0.50 (0.0196)
0.25 (0.0099)
1.27 (0.0500)
0.40 (0.0157)
45°
012407-A
Rev. F | Page 22 of 24
AD8610/AD8620
NOTES
Rev. F | Page 23 of 24
AD8610/AD8620
NOTES
©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
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