ANALOG DEVICES ADA4001-2 Service Manual

Output, JFET Dual Operational Amplifier

Data Sheet

ADA4001-2

Rev. B

Trademarks and registered trademarks are the property of their respective owners.

Fax: [phone] ©2012 Analog Devices, Inc. All rights reserved.

10375-002

OUT A

1

–IN A

2

+IN A

3

V–

4

V+

8

OUT B

7

–IN B

6

+IN B

5

ADA4001-2

TOP VIEW

(Not to S cale)

FEATURES

Low TCVOS: ±5 µV/°C typical
Low input bias current: 20 pA typical at V
Low noise

7.7 nV/√Hz typical at f = 1 kHz

1.2 µV rms at 20 Hz to 20 kHz
Low distortion: 0.00006%
No phase reversal
Rail-to-rail output
Unity-gain stable

APPLICATIONS

Instrumentation
Medical instruments
Multipole filters
Precision current measurement
Photodiode amplifiers
Sensors
Audio

Low Noise, Low Input Bias Current, Rail-to-Rail

PIN CONFIGURATION

= ±15 V

SY

Figure 1. 8-Lead SOIC_N (R Suffix)

GENERAL DESCRIPTION

The ADA4001-2 is a dual channel JFET amplifier that features
low input voltage noise and current noise, input bias current,
and rail-to-rail output.

The combination of low noise and low input bias current makes
this amplifier especially suitable for high impedance sensor
amplification. With low noise and fast settling times, the

ADA4001-2 provides good accuracy for medical instruments,

electronic measurement, and automated test equipment. Unlike
many competitive amplifiers, the ADA4001-2 maintains fast
settling performance even with substantial capacitive loads,
and, unlike many older JFET amplifiers, the ADA4001-2 does
not suffer from output phase reversal when input voltages
exceed the maximum common-mode voltage range.

With fast slew rate and great stability under capacitive loads, the

ADA4001-2 is a good fit for filter applications. With low input

bias currents and noise, it offers a wide dynamic range for photodi­ode amplifier circuits. Low noise and distortion, along with
high output current and excellent speed, make the ADA4001-2
a great choice for audio applications.

The ADA4001-2 is specified over the −40°C to +125°C extended
industrial temperature range.

The ADA4001-2 is available in an 8-lead narrow SOIC package.

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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]

www.analog.com

ADA4001-2 Data Sheet

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

Pin Configuration ............................................................................. 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

Specifications ..................................................................................... 3

Electrical Characteristics ............................................................. 3

Absolute Maximum Ratings ............................................................ 4

Thermal Resistance ...................................................................... 4

ESD Caution .................................................................................. 4

REVISION HISTORY

5/12—Rev. A to Rev B

Changes to General Description Section ...................................... 1

Changed Input Impedance to Input Capacitance Throughout .. 3

Added Input Resistance Parameter, Table 1 .................................. 3

Change to Figure 5 Caption ............................................................ 5

2/12—Rev. 0 to Rev. A

Changes to Figure 27 ........................................................................ 9

2/12—Revision 0: Initial Version

Typical Performance Characteristics ..............................................5

Applications Information .............................................................. 10

Total Noise Including Source Resistors ................................... 10

I-V Conversion Applications .................................................... 10

Input Bias Current ...................................................................... 11

Noise Considerations ................................................................. 11

Outline Dimensions ....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. B | Page 2 of 12

Data Sheet ADA4001-2

RL = 600 Ω, VO = −13.0 V to +13.0 V

90

93 dB

SY

M

Total Harmonic Distortion (THD) + Noise

THD + N

1 kHz, G = +1, RL = 2 kΩ

0.00006

%

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

VSY = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted.

Table 1.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS ±0.5 ±1.5 mV

−40°C < TA < +125°C ±2.5 mV
Offset Voltage Drift ΔVOS/ΔT ±5 µV/°C
Input Bias Current IB 20 30 pA

−40°C < TA < +125°C 4 nA
Input Offset Current IOS 20 pA

−40°C < TA < +125°C 2 nA
Input Voltage Range −12.5 +12.5 V
Common-Mode Rejection Ratio CMRR VCM = −12.5 V to +12.5 V 96 105 dB

−40°C < TA < +125°C 90 dB
Large Signal Voltage Gain AVO RL = 10 kΩ, VO = −13.5 V to +13.5 V 104 112 dB

RL = 2 kΩ, VO = −13.5 V to +13.5 V 104 112 dB

−40°C < TA < +125°C 90 dB

Input Capacitance, Differential CDM VCM = 0 V 3.1 pF
Input Capacitance, Common-Mode CCM VCM = 0 V 4.8 pF
Input Resistance VCM = 0 V >1 × 1013 Ω

OUTPUT CHARACTERISTICS

Output Voltage High VOH RL = 10 kΩ 14.8 V
RL = 2 kΩ 14.5 V
RL = 600 Ω 13.5 V
Output Voltage Low VOL RL = 10 kΩ −14.8 V
RL = 2 kΩ −14.5 V
RL = 600 Ω −13.5 V
Short-Circuit Current ISC ±50 mA

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ±4.5 V to ±18 V 96 110 dB

−40°C < TA < +125°C 93 dB
Operating Voltage Range ±5 ±18 V
Supply Current/Amplifier I

4 mA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 2 kΩ ±151 ±25 V/µs
Gain Bandwidth Product GBP VIN = 5 mV p-p, RL = 10 kΩ, AV = 100 16.7 MHz
Unity-Gain Crossover UGC VIN = 5 mV p-p, RL = 10 kΩ, AV = 1 10.2 MHz
Phase Margin φ

−3 dB Closed-Loop Bandwidth −3 dB AV = 1, VIN = 5 mV p-p 10.3 MHz
Settling Time tS To 0.01%, 10 V step, G = +1 1.2 µs

VO = 0 V 2 3 mA

76 Degrees

NOISE PERFORMANCE

Voltage Noise en rms 20 Hz to 20 kHz 1.2 μV rms
Voltage Noise Density en f = 100 Hz 8.8 nV/√Hz

f = 1 kHz 7.7 nV/√Hz

Current Noise Density in f = 1 kHz 3 fA/√Hz

1

Guaranteed by design and characterization.

Rev. B | Page 3 of 12

ADA4001-2 Data Sheet

Electrostatic Discharge

3000 V

JA

JC

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Supply Voltage ±18 V
Input Voltage ±VSY
Output Short-Circuit Duration to GND Observe derating curves
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

(Human Body Model)

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.

THERMAL RESISTANCE

Table 3.

Package Type θ

8-Lead SOIC_N (R-8) 130 45 °C/W

1

θJA is specified for worst-case conditions, that is, θJA is specified for a device

soldered in a circuit board for surface-mount packages.

1

θ

Unit

ESD CAUTION

Rev. B | Page 4 of 12

Data Sheet ADA4001-2

140

160

180

200

120
100

80

60
40

20

0

–800

–700

–600

–500

–400

–300

–200

–100

0

100

200

300

400

500

600

700

800

OFFSET VOLTAGE (µV)

NUMBER OF CHANNELS

10375-003

ADA4001-2
SOIC
V

SY

= ±15V

T

A

= 25°C

140

120

100

80

60

40

20

0

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

TCVOS (µV/°C)

ADA4001-2
V

SY

= ±15V

T

A

= –40°C TO + 125°C

NUMBER OF AMP LIFIERS

10375-004

300

200

100

0

–100

–200

–300

–15 –10 –5 0 5 10 15

COMMON-MODE INPUT VOLTAGE (V)

INPUT OFFSET VOLTAGE (µV)

10375-005

ADA4001-2
V

SY

= ±15V

T

A

= –40°C TO + 125°C

UNIT 3

UNIT 2

UNIT 1

15

10

5

0

–5

–10

–15

–15 –10 –5 0 5 10 15

COMMON-MODE INPUT VOLTAGE (V)

INPUT BIAS CURRE NT (pA)

10375-006

ADA4001-2
SOIC

V

SY

= ±15V

T

A

= 25°C

R

L

= ∞

THREE UNIT S

100

75

50

25

0

–25

–50

–15 –10 –5

+85°C

+125°C

–40°C

0 5 10 15

COMMON-MODE INPUT VOLTAGE (V)

INPUT BIAS CURRE NT (pA)

10375-007

ADA4001-2
SOIC

V

SY

= ±15V

R

L

=

∞

+25°C

10

1

0.1

0.01

0.1 1 10 100
I

OUT

SOURCE (mA)

V

DD

– V

OUT

(V)

10375-008

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, unless otherwise noted.

Figure 2. Input Offset Voltage Distribution

Figure 3. TCVOS Distribution

Figure 5. Input Bias Current vs. Common-Mode Voltage

Figure 6. Input Bias Current vs. VCM and Temperature

Figure 4. Input Offset Voltage vs. Common-Mode Voltage

Figure 7. Dropout Voltage vs. Source Current

Rev. B | Page 5 of 12

ADA4001-2 Data Sheet

10

1

0.1

0.01

0.10.01 1 10 100
I

OUT

SINK (mA)

V

OUT

– V

SS

(V)

10375-009

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

120 270

225

180

135

90

45

0

–45

–90

100

80

60

40

20

0

–20

–40

0.01 0.1 1 10 100 1k 10k 100k

FREQUENCY ( kHz )

GAIN (dB)

PHASE (Degrees)

10375-012

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

R

L

= 2kΩ

50

30

10

–10

–30

1 10 100 1k 10k 100k

FREQUENCY ( kHz )

GAIN (dB)

10375-013

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

R

L

= 2kΩ

AV = +100

AV = +10

AV = +1

1k

100

10

1

0.1

0.01

10.1 10 100 1k 10k 100k
FREQUENCY ( kHz )

Z

OUT

(Ω)

10375-014

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +100

A

V

= +10

A

V

= +1

120

100

80

60

40

20

0

–20

10.1 10 100 1k 10k
FREQUENCY ( kHz )

PSRR (dB)

10375-015

PSRR–

PSRR+

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

120

140

100

80

60

40

20

0

10.1

10 100 1k 10k

FREQUENCY ( kHz )

CMRR (dB)

10375-016

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

Figure 8. Dropout Voltage vs. Sink Current

Figure 9. Open-Loop Gain and Phase vs. Frequency

Figure 11. Closed-Loop Output Impedance vs. Frequency

Figure 12. PSRR vs. Frequency

Figure 10. Closed-Loop Gain vs. Frequency

Figure 13. CMRR vs. Frequency

Rev. B | Page 6 of 12

Data Sheet ADA4001-2

12

0.1%

0.01%

10

8

6

4

2

0

0 0.2 0.4 0.6 0.8 1.0 1.2

SETTLING TIME (µs)

STEP SIZE (V)

10375-029

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

12

8

10

4

6

0

2

–4

–2

–8

–6

–12

–10

0 2 4 6 81 3 5 7 9 10

TIME (µs)

VOLTS (V)

10375-030

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +1

R

L

= 2kΩ

C

L

= 100pF

75

50

25

0

–25

–50

–75

0 2 4 6 8 10

TIME (µs)

VOLTAGE (mV)

10375-017

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +1

R

L

= 2kΩ

C

L

= 100pF

12

0.1%

0.01%

10

8

6

4

2

0

0 0.2 0.4 0.6 0.8 1.0 1.2

SETTLING TIME (µs)

STEP SIZE (V)

10375-018

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

100

10

1

0.001

0.01

0.1 1 10 100

FREQUENCY ( kHz )

VOLTAGE NOISE DENSITY (nV/ Hz)

10375-021

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

40

45

50

35

30

0

25

20
15

10

5

0.01 0.1 1
CAPACITANCE (nF)

OVERSHOOT (%)

10375-022

OS–

OS+

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +1

Figure 14. Settling Time Positive Step

Figure 15. Large Signal Transient Response

Figure 17. Settling Time Negative Step

Figure 18. Voltage Noise Density

Figure 16. Small Signal Transient Response

Figure 19. Overshoot vs. Load Capacitance

Rev. B | Page 7 of 12

ADA4001-2 Data Sheet

–40

–60

–100

–80

–120

–140

–160

0.01 0.1 1 10 100
FREQUENCY ( kHz )

CHANNEL SEPARAT ION (dB)

10375-031

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

R

L

= 2kΩ

1

0.1

0.01

0.001

0.0001

0.00001

0.10.010.001 1 10

AMPLIT UDE ( V rms)

THD + N (%)

10375-024

ADA4001-2
V

SY

= ±15V

F

IN

= 1kHz

T

A

= 25°C

R

L

= 2kΩ

0.01

0.001

0.0001

0.00001

10.10.01 10 100

FREQUENCY ( kHz )

THD + N (%)

10375-025

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

R

L

= 2kΩ

500kHz FILTER

80kHz FILTER

20

15

10

5

0

–5

–10

–15

–20

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

TIME (ms)

VOLTS (V)

10375-026

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +1

R

L

= 2kΩ

C

L

= 100pF

OUTPUT
INPUT

12

8

10

4

6

0

2

–4

–2

–8

–6

–12

–10

0 0.4 0.8 1.2 1.60.2 0.6 1.0 1.4 1.8 2.0

TIME (µs)

VOLTS (V)

10375-032

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +1

R

L

= 2kΩ

C

L

= 100pF

12

8

10

4

6

0

2

–4

–2

–8

–6

–12

–10

0 0.4 0.8 1.2 1.60.2 0.6 1.0 1.4 1.8 2.0

TIME (µs)

VOLTS (V)

10375-033

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

A

V

= +1

R

L

= 2kΩ

C

L

= 100pF

Figure 20. Channel Separation

Figure 21. THD + N vs. Amplitude

Figure 23. No Phase Reversal

Figure 24. Positive Slew Rate

Figure 22. THD + N vs. Frequency

Figure 25. Negative Slew Rate

Rev. B | Page 8 of 12

Data Sheet ADA4001-2

300

200

100

0

–100

–200

–300

0 1 2 3 4 5 6 7 8 9 10

TIME (sec)

VOLTAGE (nV)

10375-027

ADA4001-2
V

SY

= ±15V

T

A

= 25°C

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0 ±2 ±4 ±6 ±8 ±10 ±12 ±14 ±16 ±18

V

SY

(V)

I

SY

FOR BOTH AMPLIFIERS (mA)

10375-028

ADA4001-2
NO LOAD
A

V

= +1

V

CM

= 0V

+125°C
+85°C
+25°C
–40°C

Figure 26. Peak-to-Peak Voltage Noise

Figure 27. Supply Current vs. Supply Voltage and Temperature

Rev. B | Page 9 of 12

ADA4001-2 Data Sheet

APPLICATIONS INFORMATION

TOTAL NOISE INCLUDING SOURCE RESISTORS

The low input current noise and input bias current of the

ADA4001-2 makes it the ideal amplifier for circuits with

substantial input source resistance. Input offset voltage
increases by less than 15 nV per 500 Ω of source resistance
at room temperature. The total noise density of the circuit is

nTOTAL

2

where:

e

is the input voltage noise density of the part.

n

i

is the input current noise density of the part.

n

R

is the source resistance at the noninverting terminal.

S

k is Boltzmann’s constant (1.38 × 10
T is the ambient temperature in Kelvin (T = 273 + °C).

< 4 kΩ, en dominates and e

For R

S

noise of the ADA4001-2 is so low that its total density does
not become a significant term unless R
100 MΩ, an impractical value for most applications.

The total equivalent rms noise over a specific bandwidth is
expressed as



nTOTALnTOTAL

where

BW is the bandwidth in hertz.

Note that the previous analysis is valid for frequencies larger
than 150 Hz and assumes flat noise above 10 kHz. For lower
frequencies, flicker noise (1/f) must be considered.

I-V CONVERSION APPLICATIONS

Photodiode Circuits

Common applications for I-V conversion include photodiode
circuits where the amplifier is used to convert a current emitted
by a diode placed at the positive input terminal into an output
voltage.

The ADA4001-2 low input bias current, wide bandwidth, and
low noise makes it an excellent choice for various photodiode
applications, including fax machines, fiber optic controls,
motion sensors, and bar code readers.

The circuit shown in Figure 28 uses a silicon diode with
zero bias voltage. This is known as a photovoltaic mode;
this configuration limits the overall noise and is suitable for
instrumentation applications.

2



nn

kTRRiee 4



nTO TAL

BWee

SS

–23

J/K).

≈ e

. The current

n

is greater than

S

Cf

R2

V

EE

4

2

ADA4001-2

Rd Ct

Figure 28. Equivalent Preamplifier Photodiode Circuit

3

1

8

V

CC

10375-034

A larger signal bandwidth can be attained at the expense of
additional output noise. The total input capacitance (Ct)
consists of the sum of the diode capacitance and the amplifier’s
input capacitance (8 pF), which includes external parasitic
capacitance. Ct creates a pole in the frequency response that can
lead to an unstable system. To ensure stability and optimize the
bandwidth of the signal, a capacitor is placed in the feedback
loop of the circuit shown in Figure 28. It creates a zero and
yields a bandwidth whose corner frequency is 1/(2π(R2Cf)).

The value of R2 can be determined by the ratio

V/I

D

where:

V is the desired output voltage of the op amp.
I

is the diode current.

D

For example, if I

is 100 μA and a 10 V output voltage is desired,

D

R2 should be 100 kΩ. Rd (see Figure 28) is a junction resistance
that drops typically by a factor of 2 for every 10°C increase in
temperature.

A typical value for Rd is 1000 MΩ. Because Rd >> R2, the
circuit behavior is not impacted by the effect of the junction
resistance. The maximum signal bandwidth is

MAX

CtR

22



ft



f

where ft is the unity gain frequency of the amplifier.
Cf can be calculated by

Cf

Ct



ftR

22



where ft is the unity gain frequency of the op amp, and it achieves
a phase margin, φ

, of approximately 45°.

M

A higher phase margin can be obtained by increasing the value
of Cf. Setting Cf to twice the previous value yields approximately

= 65° and a maximal flat frequency response, but it reduces the

φ

M

maximum signal bandwidth by 50%.

Rev. B | Page 10 of 12

Data Sheet ADA4001-2

INPUT BIAS CURRENT

Because the ADA4001-2 has a JFET input stage, the input bias
current, due to the reverse-biased junction, has a leakage
current that approximately doubles every 10°C. The power
dissipation of the part, combined with the thermal resistance of
the package, results in the junction temperature increasing 30°C
above ambient. This parameter is tested with high speed ATE
equipment, which does not result in the die temperature
reaching equilibrium. This is correlated with bench
measurements to match the guaranteed maximum at room
temperature in Table 1.

The input current can be reduced by keeping the temperature as
low as possible and using a light load on the output.

NOISE CONSIDERATIONS

The JFET input stage offers very low input voltage noise and
input current noise. The thermal noise of a 1 kΩ resistor at
room temperature is 4 nV/√Hz, thus low values of resistance
should be used for dc-coupled inverting and noninverting
amplifier configurations. In the case of transimpedance
amplifiers (TIAs), current noise is more important.

The ADA4001-2 is an excellent choice for both of these
applications. Analog Devices, Inc., offers a wide variety of low
voltage noise and low current noise op amps in a variety of
processes optimized for different supply voltage ranges. Refer
to the AN-940 Application Note for a complete discussion of
noise, calculations, and selection tables for more than three
dozen low noise, op amp families.

Rev. B | Page 11 of 12

ADA4001-2 Data Sheet

CONTROL

LING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSI

ONS

(IN PARENTHESES)ARE ROUNDED-OFF MILLIMETER E

QUIVALENTS FOR

REFERENCE ONLYAND ARE NOT APPROPRI

ATE FOR USE IN DESIGN.

COMPLIANT TO JEDEC STANDARD

S MS-012-AA

012407-A

0.25 (0.0098)

0.1

7 (0.0067)

1.27 (0.0500)

0.40 (0.0157)

0.50 (0.0196)

0.25 (0.0099)

45°

8°
0°

1

.75 (0.0688)

1.35 (0.0532)

SEATING

P

LANE

0.25 (0.0098)

0.10 (0.0040)

4

1

8 5

5.00(0.1968)
4

.80(0.1890)

4.00 (0.1574)

3.80

(0.1497)

1.27 (0.0500)
BSC

6.20 (0.2441)

5.80

(0.2284)

0.51 (0.0201)

0.31 (0.0122)

COPLA

NARITY

0.10

©2012 Analog Devices, Inc. All rights reserved. Trademarks and

OUTLINE DIMENSIONS

Figure 29. 8-Lead Standard Small Outline Package [SOIC_N]

Narrow Body (R-8)

Dimensions shown in millimeters and (inches)

ORDERING GUIDE

Model1 Temperature Range Package Description Package Option

ADA4001-2ARZ −40°C to +125°C 8-Lead SOIC_N R-8
ADA4001-2ARZ-R7 −40°C to +125°C 8-Lead SOIC_N R-8
ADA4001-2ARZ-RL −40°C to +125°C 8-Lead SOIC_N R-8

1

Z = RoHS Compliant Part.

registered trademarks are the property of their respective owners.
D10375-0-5/12(B)

Rev. B | Page 12 of 12