AD8429_16 Datasheet, PDF (1/21 Pages) Analog Devices – 1 nV/√Hz Low Noise Instrumentation Amplifier

FEATURES
Low noise
1 nV/√Hz input noise
45 nV/√Hz output noise
High accuracy dc performance (AD8429BRZ)
90 dB CMRR minimum (G = 1)
50 μV maximum input offset voltage
0.02% maximum gain accuracy (G = 1)
Excellent ac specifications
80 dB CMRR to 5 kHz (G = 1)
15 MHz bandwidth (G = 1)
1.2 MHz bandwidth (G = 100)
22 V/μs slew rate
THD: −130 dBc (1 kHz, G = 1)
Versatile
±4 V to ±18 V dual supply
Gain set with a single resistor (G = 1 to 10,000)
Temperature range for specified performance
−40°C to +125°C
APPLICATIONS
Medical instrumentation
Precision data acquisition
Microphone preamplification
Vibration analysis
GENERAL DESCRIPTION
The AD8429 is an ultralow noise, instrumentation amplifier
designed for measuring extremely small signals over a wide
temperature range (−40°C to +125°C).
The AD8429 excels at measuring tiny signals. It delivers ultralow
input noise performance of 1 nV/√Hz. The high CMRR of the
AD8429 prevents unwanted signals from corrupting the acqui-
sition. The CMRR increases as the gain increases, offering high
rejection when it is most needed. The high performance pin
configuration of the AD8429 allows it to reliably maintain high
CMRR at frequencies well beyond those of typical instrumentation
amplifiers.
The AD8429 reliably amplifies fast changing signals. Its current
feedback architecture provides high bandwidth at high gain, for
example, 1.2 MHz at G = 100. The design includes circuitry to im-
prove settling time after large input voltage transients. The AD8429
was designed for excellent distortion performance, allowing use in
demanding applications such as vibration analysis.
Gain is set from 1 to 10,000 with a single resistor. A reference
pin allows the user to offset the output voltage. This feature can
Rev. 0
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1 nV/√Hz Low Noise
Instrumentation Amplifier
AD8429
PIN CONNECTION DIAGRAM
–IN 1
R_G 2
R_G 3
+IN 4
AD8429
8 +V_S
7 V_OUT
6 REF
5 –V_S
TOP VIEW
(Not to Scale)
Figure 1.
be useful to shift the output level when interfacing to a single
supply signal chain.
The AD8429 performance is specified over the extended industrial
temperature range of −40°C to +125°C. It is available in an 8-lead
plastic SOIC package.
1000
100
G=1
10
G = 10
G = 100
1
G = 1k
0.1
1
10
100
1k
10k
100k
FREQUENCY (Hz)
Figure 2. RTI Voltage Noise Spectral Density vs. Frequency
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