Low Noise, Low Input Bias Current, Rail-to-Rail
Output, JFET Dual Operational Amplifier
ADA4001-2
Data Sheet
PIN CONFIGURATION
Low TCVOS: ±5 µV/°C typical
Low input bias current: 20 pA typical at VSY = ±15 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
OUT A 1
–IN A 2
+IN A 3
V– 4
ADA4001-2
TOP VIEW
(Not to Scale)
8
V+
7
OUT B
6
–IN B
5
+IN B
10375-002
FEATURES
Figure 1. 8-Lead SOIC_N (R Suffix)
APPLICATIONS
Instrumentation
Medical instruments
Multipole filters
Precision current measurement
Photodiode amplifiers
Sensors
Audio
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.
Rev. C
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.
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Technical Support
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ADA4001-2
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Typical Performance Characteristics ..............................................5
Applications ....................................................................................... 1
Applications Information .............................................................. 10
Pin Configuration ............................................................................. 1
Total Noise Including Source Resistors ................................... 10
General Description ......................................................................... 1
I-V Conversion Applications .................................................... 10
Revision History ............................................................................... 2
Input Bias Current ...................................................................... 11
Specifications..................................................................................... 3
Noise Considerations ................................................................. 11
Electrical Characteristics ............................................................. 3
Outline Dimensions ....................................................................... 12
Absolute Maximum Ratings ............................................................ 4
Ordering Guide .......................................................................... 12
Thermal Resistance ...................................................................... 4
ESD Caution .................................................................................. 4
REVISION HISTORY
5/13—Rev. B to Rev C
Changes to Photodiode Circuits Section ..................................... 10
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
Rev. C | Page 2 of 12
Data Sheet
ADA4001-2
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
VSY = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Symbol
Test Conditions/Comments
Min
VOS
Typ
Max
Unit
±0.5
±1.5
±2.5
93
3.1
4.8
>1 × 1013
mV
mV
µV/°C
pA
nA
pA
nA
V
dB
dB
dB
dB
dB
dB
pF
pF
Ω
±50
V
V
V
V
V
V
mA
−40°C < TA < +125°C
Offset Voltage Drift
Input Bias Current
ΔVOS/ΔT
IB
±5
20
−40°C < TA < +125°C
Input Offset Current
IOS
−40°C < TA < +125°C
Input Voltage Range
Common-Mode Rejection Ratio
CMRR
Large Signal Voltage Gain
AVO
Input Capacitance, Differential
Input Capacitance, Common-Mode
Input Resistance
OUTPUT CHARACTERISTICS
Output Voltage High
Output Voltage Low
Short-Circuit Current
POWER SUPPLY
Power Supply Rejection Ratio
Operating Voltage Range
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
Unity-Gain Crossover
Phase Margin
−3 dB Closed-Loop Bandwidth
Settling Time
Total Harmonic Distortion (THD) + Noise
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
1
CDM
CCM
VOH
VOL
VCM = −12.5 V to +12.5 V
−40°C < TA < +125°C
RL = 10 kΩ, VO = −13.5 V to +13.5 V
RL = 2 kΩ, VO = −13.5 V to +13.5 V
−40°C < TA < +125°C
RL = 600 Ω, VO = −13.0 V to +13.0 V
VCM = 0 V
VCM = 0 V
VCM = 0 V
RL = 10 kΩ
RL = 2 kΩ
RL = 600 Ω
RL = 10 kΩ
RL = 2 kΩ
RL = 600 Ω
−12.5
96
90
104
104
90
90
VS = ±4.5 V to ±18 V
−40°C < TA < +125°C
ISY
VO = 0 V
SR
GBP
UGC
φM
−3 dB
tS
THD + N
RL = 2 kΩ
VIN = 5 mV p-p, RL = 10 kΩ, AV = 100
VIN = 5 mV p-p, RL = 10 kΩ, AV = 1
en rms
en
in
105
112
112
14.8
14.5
13.5
−14.8
−14.5
−13.5
ISC
PSRR
30
4
20
2
+12.5
96
93
±5
110
2
AV = 1, VIN = 5 mV p-p
To 0.01%, 10 V step, G = +1
1 kHz, G = +1, RL = 2 kΩ
±25
16.7
10.2
76
10.3
1.2
0.00006
V/µs
MHz
MHz
Degrees
MHz
µs
%
20 Hz to 20 kHz
f = 100 Hz
f = 1 kHz
f = 1 kHz
1.2
8.8
7.7
3
μV rms
nV/√Hz
nV/√Hz
fA/√Hz
Guaranteed by design and characterization.
Rev. C | Page 3 of 12
±15 1
±18
3
4
dB
dB
V
mA
mA
ADA4001-2
Data Sheet
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 2.
Parameter
Supply Voltage
Input Voltage
Output Short-Circuit Duration to GND
Storage Temperature Range
Operating Temperature Range
Junction Temperature Range
Lead Temperature (Soldering, 10 sec)
Electrostatic Discharge
(Human Body Model)
Rating
±18 V
±VSY
Observe derating curves
−65°C to +150°C
−40°C to +125°C
−65°C to +150°C
300°C
3000 V
Table 3.
Package Type
8-Lead SOIC_N (R-8)
1
θJA1
130
θJC
45
Unit
°C/W
θJA is specified for worst-case conditions, that is, θJA is specified for a device
soldered in a circuit board for surface-mount packages.
ESD CAUTION
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.
Rev. C | Page 4 of 12
Data Sheet
ADA4001-2
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, unless otherwise noted.
200
INPUT BIAS CURRENT (pA)
160
140
120
100
80
60
40
0
–5
800
10375-003
700
600
500
400
300
200
0
100
–100
–200
–300
–400
–500
–600
–700
–800
OFFSET VOLTAGE (µV)
–15
–15
Figure 2. Input Offset Voltage Distribution
ADA4001-2
SOIC
VSY = ±15V
RL = ∞
75
INPUT BIAS CURRENT (pA)
100
80
60
40
20
+125°C
50
+25°C
25
+85°C
0
–40°C
TCVOS (µV/°C)
–50
–15
10375-004
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
–25
Figure 3. TCVOS Distribution
ADA4001-2
VSY = ±15V
TA = –40°C TO +125°C
100
10
VDD – VOUT (V)
UNIT 3
0
UNIT 2
–100
15
ADA4001-2
VSY = ±15V
TA = 25°C
1
0.1
UNIT 1
–10
–5
0
5
10
COMMON-MODE INPUT VOLTAGE (V)
15
0.01
0.1
10375-005
–200
–300
–15
0
5
10
–5
COMMON-MODE INPUT VOLTAGE (V)
Figure 6. Input Bias Current vs. VCM and Temperature
300
200
–10
10375-007
NUMBER OF AMPLIFIERS
15
100
ADA4001-2
VSY = ±15V
TA = –40°C TO +125°C
120
INPUT OFFSET VOLTAGE (µV)
0
5
10
–5
COMMON-MODE INPUT VOLTAGE (V)
Figure 5. Input Bias Current vs. Common-Mode Voltage
140
0
–10
10375-006
–10
20
0
ADA4001-2
SOIC
VSY = ±15V
10 TA = 25°C
RL = ∞
THREE UNITS
5
1
10
IOUT SOURCE (mA)
Figure 7. Dropout Voltage vs. Source Current
Figure 4. Input Offset Voltage vs. Common-Mode Voltage
Rev. C | Page 5 of 12
100
10375-008
NUMBER OF CHANNELS
15
ADA4001-2
SOIC
VSY = ±15V
TA = 25°C
180
ADA4001-2
Data Sheet
1k
10
ADA4001-2
VSY = ±15V
TA = 25°C
ADA4001-2
VSY = ±15V
TA = 25°C
ZOUT (Ω)
1
10
AV = +100
1
AV = +10
0.1
0.1
1
IOUT SINK (mA)
10
100
0.01
0.1
Figure 8. Dropout Voltage vs. Sink Current
60
135
40
90
20
45
0
80
PSRR (dB)
180
–20
10
100
FREQUENCY (kHz)
1k
10k
40
PSRR+
0
–45
1
PSRR–
60
20
0
0.1
–90
100k
–20
0.1
1
10
100
FREQUENCY (kHz)
Figure 9. Open-Loop Gain and Phase vs. Frequency
50
AV = +100
1k
10k
Figure 12. PSRR vs. Frequency
140
ADA4001-2
VSY = ±15V
TA = 25°C
RL = 2kΩ
ADA4001-2
VSY = ±15V
TA = 25°C
120
30
100
CMRR (dB)
AV = +10
10
AV = +1
80
60
40
–10
–30
1
10
100
1k
FREQUENCY (kHz)
10k
100k
0
0.1
Figure 10. Closed-Loop Gain vs. Frequency
1
10
100
FREQUENCY (kHz)
Figure 13. CMRR vs. Frequency
Rev. C | Page 6 of 12
1k
10k
10375-016
20
10375-013
GAIN (dB)
100k
ADA4001-2
VSY = ±15V
TA = 25°C
100
PHASE (Degrees)
80
–40
0.01
10k
120
10375-012
GAIN (dB)
100
10
100
1k
FREQUENCY (kHz)
Figure 11. Closed-Loop Output Impedance vs. Frequency
270
ADA4001-2
VSY = ±15V
TA = 25°C 225
RL = 2kΩ
120
1
10375-014
0.1
10375-009
0.01
0.01
AV = +1
10375-015
VOUT – VSS (V)
100
Data Sheet
ADA4001-2
12
12
ADA4001-2
VSY = ±15V
TA = 25°C
10
8
0.1%
6
0.01%
6
0.1%
0.01%
4
4
2
2
0
0
0.2
0.4
0.6
0.8
SETTLING TIME (µs)
1.0
1.2
0
0
0.2
Figure 14. Settling Time Positive Step
0.4
0.6
0.8
SETTLING TIME (µs)
100
ADA4001-2
VSY = ±15V
TA = 25°C
10
VOLTAGE NOISE DENSITY (nV/ Hz)
8
6
VOLTS (V)
4
ADA4001-2
VSY = ±15V
TA = 25°C
AV = +1
RL = 2kΩ
CL = 100pF
0
–2
–4
1.2
Figure 17. Settling Time Negative Step
12
2
1.0
10375-018
STEP SIZE (V)
8
10375-029
STEP SIZE (V)
ADA4001-2
VSY = ±15V
TA = 25°C
10
–6
–8
10
0
1
2
3
4
5
6
TIME (µs)
7
8
9
10
1
0.001
10375-030
–12
Figure 15. Large Signal Transient Response
0.1
1
FREQUENCY (kHz)
10
100
Figure 18. Voltage Noise Density
75
50
45
50
40
ADA4001-2
VSY = ±15V
TA = 25°C
AV = +1
35
OVERSHOOT (%)
25
ADA4001-2
VSY = ±15V
TA = 25°C
AV = +1
RL = 2kΩ
CL = 100pF
0
–25
OS+
30
25
20
15
OS–
10
–50
–75
0
2
4
6
8
TIME (µs)
10
0
0.01
Figure 16. Small Signal Transient Response
0.1
CAPACITANCE (nF)
1
Figure 19. Overshoot vs. Load Capacitance
Rev. C | Page 7 of 12
10375-022
5
10375-017
VOLTAGE (mV)
0.01
10375-021
–10
ADA4001-2
Data Sheet
20
–40
ADA4001-2
VSY = ±15V
TA = 25°C
RL = 2kΩ
10
–80
5
VOLTS (V)
–100
0
–5
–120
–10
–140
OUTPUT
INPUT
–15
0.1
1
FREQUENCY (kHz)
10
100
–20
10375-031
–160
0.01
0
0.1
0.2
Figure 20. Channel Separation
0.4
0.5
0.6
TIME (ms)
0.7
0.8
0.9
1.0
1.6
1.8
2.0
Figure 23. No Phase Reversal
1
12
ADA4001-2
VSY = ±15V
FIN = 1kHz
TA = 25°C
RL = 2kΩ
0.1
ADA4001-2
VSY = ±15V
TA = 25°C
AV = +1
RL = 2kΩ
CL = 100pF
10
8
6
4
0.01
VOLTS (V)
THD + N (%)
0.3
10375-026
CHANNEL SEPARATION (dB)
–60
ADA4001-2
VSY = ±15V
TA = 25°C
AV = +1
RL = 2kΩ
CL = 100pF
15
0.001
2
0
–2
–4
–6
0.0001
–8
0.01
0.1
AMPLITUDE (V rms)
1
10
–12
10375-024
0.00001
0.001
0
0.2
0.4
Figure 21. THD + N vs. Amplitude
0.01
0.6
0.8
1.0
1.2
TIME (µs)
1.4
Figure 24. Positive Slew Rate
12
ADA4001-2
VSY = ±15V
TA = 25°C
RL = 2kΩ
ADA4001-2
VSY = ±15V
TA = 25°C
AV = +1
RL = 2kΩ
CL = 100pF
10
8
6
4
VOLTS (V)
THD + N (%)
0.001
500kHz FILTER
0.0001
10375-032
–10
2
0
–2
–4
80kHz FILTER
–6
–8
0.1
1
FREQUENCY (kHz)
10
100
Figure 22. THD + N vs. Frequency
–12
0
0.2
0.4
0.6
0.8
1.0
1.2
TIME (µs)
1.4
Figure 25. Negative Slew Rate
Rev. C | Page 8 of 12
1.6
1.8
2.0
10375-033
0.00001
0.01
10375-025
–10
Data Sheet
ADA4001-2
3.5
300
ADA4001-2
VSY = ±15V
TA = 25°C
3.0
0
–100
–200
2.0
1.5
1.0
+125°C
+85°C
+25°C
–40°C
0.5
–300
0
1
2
3
4
6
5
TIME (sec)
7
8
9
10
0
10375-027
VOLTAGE (nV)
100
ADA4001-2
NO LOAD
AV = +1
VCM = 0V
2.5
0
Figure 26. Peak-to-Peak Voltage Noise
±2
±4
±6
±8
±10
VSY (V)
±12
±14
±16
±18
Figure 27. Supply Current vs. Supply Voltage and Temperature
Rev. C | Page 9 of 12
10375-028
ISY FOR BOTH AMPLIFIERS (mA)
200
ADA4001-2
Data Sheet
APPLICATIONS INFORMATION
Cf
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
R2
VEE
2
ADA4001-2
Rd
Ct
1
3
8
VCC
where:
en is the input voltage noise density of the part.
in is the input current noise density of the part.
RS is the source resistance at the noninverting terminal.
k is Boltzmann’s constant (1.38 × 10–23 J/K).
T is the ambient temperature in Kelvin (T = 273 + °C).
10375-034
e nTOTAL  e n 2  i n R S 2  4kTR S
Figure 28. Equivalent Preamplifier Photodiode Circuit
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)).
For RS < 4 kΩ, en dominates and enTOTAL ≈ en. The current
noise of the ADA4001-2 is so low that its total density does
not become a significant term unless RS is greater than
100 MΩ, an impractical value for most applications.
The total equivalent rms noise over a specific bandwidth is
expressed as
The value of R2 can be determined by the ratio
enTOTAL  enTOTAL BW
V/ID
where:
V is the desired output voltage of the op amp.
ID is the diode current.
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.
For example, if ID is 100 μA and a 10 V output voltage is desired,
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.
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 negative 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.
4
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
f MAX 
ft
2R2Ct
where ft is the unity gain frequency of the amplifier.
Cf can be calculated by
Cf 
Ct
2R2 ft
where ft is the unity gain frequency of the op amp, and it achieves
a phase margin, φM, of approximately 45°.
A higher phase margin can be obtained by increasing the value
of Cf. Setting Cf to twice the previous value yields approximately
φM = 65° and a maximal flat frequency response, but it reduces the
maximum signal bandwidth by 50%.
Rev. C | Page 10 of 12
Data Sheet
ADA4001-2
INPUT BIAS CURRENT
NOISE CONSIDERATIONS
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 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 input current can be reduced by keeping the temperature as
low as possible and using a light load on the output.
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. C | Page 11 of 12
ADA4001-2
Data Sheet
OUTLINE DIMENSIONS
5.00 (0.1968)
4.80 (0.1890)
1
5
4
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
0.10
SEATING
PLANE
6.20 (0.2441)
5.80 (0.2284)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.31 (0.0122)
0.50 (0.0196)
0.25 (0.0099)
45°
8°
0°
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-012-AA
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.
012407-A
8
4.00 (0.1574)
3.80 (0.1497)
Figure 29. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body (R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model1
ADA4001-2ARZ
ADA4001-2ARZ-R7
ADA4001-2ARZ-RL
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
Z = RoHS Compliant Part.
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D10375-0-5/13(C)
Rev. C | Page 12 of 12
Package Option
R-8
R-8
R-8