How many Op-amps do I need to amplify Bridge Sensors output

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carrotts

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brige opamp

Can anyone help me. I am trying to interface a bridge sensor measuring gas pressure to a PIc. The output of the bridge is 0-40mV differential, offset around 2.52V. i.e. at 0 psi both bridge output pins are at 2.52 V, at around 50 psi the + pin is at 2.54 and the - pin is at 2.50. I can not get the accuracy required using only the PICs A/D so I need to amplify the output. What is the least number of op-amps I can use to do this. I only need an accuracy of about 1 PSI, so accuracy is not too important.

Thanks

carrotts
 

www.linear.com an43.pdf

Hi

You are usually using an instrumentation amplifier.
A monolithic one likes AD622 from Analog Devices
or use a circuit with 2 or 3 separate OP-AMP.
Other manufactures of Inst. Amp are Texas instrument, Linear technology, Maxim, ST and more...
Linear technology has a good app note, see
https://www.linear.com/pdf/an43.pdf
 

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