DIFFERENTIAL MICROPHONE WITH DUAL POLARITY BIAS

摘要

Methods and system are described for cancelling interference in a microphone system. A positive bias voltage is applied to a first microphone diaphragm and a negative bias voltage is applied to a second microphone diaphragm. The diaphragms are configured to exhibit substantially the same mechanical deflection in response to acoustic pressures received by the microphone system. A differential output signal is produced by combining a positively-biased output signal from the first microphone diaphragm and a negatively-biased output signal from the second microphone diaphragm. This combining cancels common-mode interferences that are exhibited in both the positively-biased output signal and the negatively-biased output signal.

主权项

1. A microphone system including:
a first microphone diaphragm positioned to receive acoustic pressure from a first direction, wherein a positive bias voltage is applied to the first diaphragm; a second microphone diaphragm positioned to receive acoustic pressure from the first direction at substantially the same amplitude as the acoustic pressure received by the first microphone diaphragm, wherein a negative bias voltage is applied to the first diaphragm; and a differential amplifier configured to
receive a positively-biased output from the first microphone diaphragm and a negatively-biased output from the second microphone diaphragm, andproduce a differential signal based on the positively-biased output and the negatively-biased output.