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AD8233 fixed gain; why so high?

Question asked by Ribred on Feb 24, 2017
Latest reply on Mar 1, 2017 by Emman.A

Hi all,

I have been trying the AD8233 using its evaluation board and reading up on typical ECG AFE implementations.  Many application notes indicate the typical instrumentation amp gain is less than x10 so the typical offset voltage between electrodes (as much as +/-300mV) does not saturate the INA.

 

However, the AD8233 has a fixed gain of x100?  Why is this so high?

 

Is this because the expected application is for something like a single limb (wrist or arm) electrode pair?  Perhaps then the maximum voltage difference would be lower than what is expected for typical ECG electrodes on different limbs (i.e. LA, RA, LL).

 

Cheers and thanks in advance for a response.

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