I have a design for an EMG (electro-myograph) that needs some stability assistance. The core components are an LT6370 in-amp, and an OPA2192 dual op-amp package for amplification and generating a stable reference. The reference is set by a capacitance multiplier that seems solid as a rock when probed. The in-amp is set to ~1.5 X and the op-amp (not as ref) is set to ~ 30 X in a Sallen-key configuration to snuff high f noise. The reference is pushed to the patients skin as well in a driven right-leg configuration. This is of course just on a bench top right now so no confounding lead attachment issues.
The circuit occasionally acts properly, but mostly finds itself sitting at the ground rail. In shorting the input leads of the in-amp I expect 2.485V out of my in-amp and thus of course 0 out of my 2nd amplifier.
Am I missing something easy? LTSpice shows this operating great (of course it would!) Any ideas on what to check? I'm flummoxed.
The circuit occasionally acts properly, but mostly finds itself sitting at the ground rail. In shorting the input leads of the in-amp I expect 2.485V out of my in-amp and thus of course 0 out of my 2nd amplifier.
Am I missing something easy? LTSpice shows this operating great (of course it would!) Any ideas on what to check? I'm flummoxed.
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