A Novel Digital Radio-Frequency Capacitor Microphone With Gain Ranging

摘要

Most capacitor microphones use an audio-frequency (AF) implementation. In an AF circuit, a capacitor is charged with a constant bias voltage leading to a high-impedance circuit. In contrast, by using a radio-frequency (RF) approach, the capacitor is operated on a higher frequency band which reduces the circuit's impedance. However, state of the art RF microphones are entirely analog. Thus, a novel digital RF condenser microphone system is proposed. Furthermore, it is extended by a corresponding gain ranging approach. The expected advantages are a further improved demodulation linearity due to a digital demodulation and a circumvention of analog disadvantages due to the smaller required analog circuit. Additionally, because of the analog bandpass signal, it is expected to utterly bypass the electrical low frequency 1/f noise.