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strain gauge amplifier for differential ADC

Question asked by Alexxx on Jul 26, 2013
Latest reply on Jul 29, 2013 by ScottH

Hello,

 

I need a strain gauge amplifier + ADC driver for an differential 24 bit ADC (AD7791) with low sample rate,

so a 0 to 10Hz bandwith of the amplifier is sufficient.

The challenge is: It must have lowest possible DC to 10Hz Noise at a gain of 800, complexity doesn't matter.

Also high gain stability and high linearity (< 50 ppm) is needed.

The strain gauge resistance is 1K, ratiometric measurement needed.

5V single supply + Rail-Rail-out would be nice but is not needed.

I've looked the circuit of EVAL-CN0216-SDPZ, which uses the ADA4528 auto-zero-OPA, but noise performance is not perfect -
data sheet ADA4528: 100nVpp 0.1 Hz to 10 Hz Noise. And

Then I found an chopper amp circuit with 40nVpp 0,1...10Hz noise (http://cds.linear.com/docs/en/datasheet/201a23fb.pdf  at page 9).

But this circuit don't have a differential input nor a differential output.

Does anyone knows a (chopper-) circuit that has lower peak-peak noise than ADA4528?

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