Analog Devices Inc. AD8422 Instrumentation Amplifiers

Analog Devices Inc. AD8422 Instrumentation Amplifier processes signals with ultralow distortion performance that is load independent over its full output range. Very low bias current makes the AD8422 error-free with high source impedance, allowing multiple sensors to be multiplexed to the inputs. Low voltage noise and low current noise make the AD8422 an ideal choice for measuring a Wheatstone bridge.

The AD8422 uses robust input protection that ensures reliability without sacrificing noise performance. The AD8422 has high ESD immunity, and the inputs are protected from continuous voltages up to 40 V from the opposite supply rail. A single resistor sets the gain from 1 to 1000. The reference pin can be used to apply a precise offset to the output voltage. The AD8422 is specified from −40°C to +85°C and has typical performance curves to 125°C. It is available in 8-lead MSOP and 8-lead SOIC packages.

Features

330μA maximum quiescent current
Rail-to-rail output
Low noise and distortion
- 8nV/√Hz maximum input voltage noise at 1kHz
- 0.15μV p-p RTI noise (G=100)
- 0.5ppm nonlinearity with 2kΩ load (G = 1)
Excellent ac specifications
- 80dB minimum CMRR at 7kHz (G = 1)
- 2.2MHz bandwidth (G = 1)

High precision dc performance (AD8422BRZ)
- 150dB minimum CMRR (G = 1000)
- 0.04% maximum gain error (G = 1000)
- 0.3μV/°C maximum input offset drift
- 0.5nA maximum input bias current
Wide supply range
- 3.6V to 36V single supply
- ±1.8V to ±18V dual supply
40V from opposite supply Input overvoltage protection
1 to 1000 Gain range

Applications

Medical instrumentation
Industrial process controls
Strain gauges
Transducer interfaces

Precision data acquisition systems
Channel-isolated systems
Portable instrumentation

Additional Resources

Achieving a Fully Differential Output Using Single-Ended Instrumentation Amplifiers

As the drive for precision moves forward, fully differential signal chain components are desired for their performance with one of the major advantages being noise rejection that can be picked up by signal routing. So can we generate a differential output signal using instrumentation amplifiers?

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