A voltage supply circuit includes a power supply booster, an amplifier operating with a voltage generated by the power supply booster as a power supply voltage and supplying a bias voltage to a sensor, and an output voltage setting part including a feedback resistor for the amplifier. The feedback resistor...http://www.google.com.hk/patents/US7929716?utm_source=gb-gplus-share專利 US7929716 - Voltage supply circuit, power supply circuit, microphone unit using the same, and microphone unit sensitivity adjustment method
