A/D converter with integrated biasing for a microphone

摘要

A combination of a microphone and a sigma-delta A/D converter include at least one feedback loop, such as a DC feedback loop. The DC feedback loop provides the bias current for a junction FET of the microphone. In this way, the signal current from the FET can be injected directly into the input integrator of the sigma-delta A/D converter without the need of signal resistors in series with the FET.