Yea it is ( the 1Gig) needed. ?The capsule has a capacitance of 15-55pF so that forms an RC filter that takes care of the noise. It also provides DC bias to the FET (or What ever the Impedance converter is) and finally develops the voltage to get sensed. ?There are some fets, usually the internal to an electret ones that have a ¡°leakage diode¡± in them that serves ?the same purpose?
Best Regards,
Jules Ryckebusch?
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On Jun 3, 2022, at 12:08, blair.r.conner@... wrote:
?Thanks Jules! Found the schematic. Is a 1G Ohm resistor really needed? Why such a high value? Wouldn't this add noise to the circuit?
