| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To maximally and efficiently swing an output voltage within a voltage range from a ground potential GND to an external power-supply voltage VDD. <P>SOLUTION: A microphone amplifier has an input terminal 11 connected to a microphone 1, an output terminal 12 connected to an external power-supply terminal 3 through a load resistor 2 and a ground terminal 13 connected to a ground. The microphone amplifier further has an amplifier 14 amplifying a signal input to the input terminal 11 and a driving circuit 15 driving the output terminal 12 by inputting an output signal from the amplifier 14. An internal power-supply terminal 18 for connecting a capacitor 4 between the microphone amplifier and the ground, and the internal power-supply terminal 18 is connected at a power-supply terminal for the amplifier 14 while the series circuit of a current-limiting circuit 17 and a diode 16 is connected between the internal power-supply terminal 18 and the output terminal 12. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
