| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply system for an electrostatic microphone that is not susceptible to an effect of a power supply or ground and causes less noise, SOLUTION: A couple of complementary bipolar transistors(TRs) 10, 11 generate a positive voltage and a negative voltage with respect to a reference voltage from a reference voltage generating circuit 1 of a microphone amplifier 7 that detects and amplifies a voice output from a condenser microphone 5 and the positive voltage and the negative voltage generated by the TRs are given to both terminals of the condenser microphone 5. Since a base current of the TRs is based on a voltage from the reference voltage generating circuit 1, a voice signal outputted from the condenser microphone 5 includes very less superimposition of a noise from a power supply VCC and ground, resulting that the voice output to a differential amplifier 20 being a component of the microphone amplifier 7 includes less noise.
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