| 摘要 |
An FM modulator (1) includes two phase shifting circuits (110C and 30C) and a capacitor microphone (14-1) is provided in the circuit (110C). The FM modulator (1) oscillates at the frequency at which the sum of the amounts of phase shift of the two circuits (110C and 30C) is 360 DEG . When the capacitance of the microphone (14-1) is slightly changed by the sound pressure, the modulator (1) outputs FM signals from an output terminal (92) by directly utilizing the change for the frequency modulation. |
