| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a signal amplifier to be used for in-vehicle audio equipment or the like for effectively reducing a common mode noise of a relatively high frequency which leaks to an input terminal. Ž<P>SOLUTION: An input signal (audio signal) is input to the hot end of an input terminal 11, and a cold end is grounded through a ground resistance 16. The hot end of the input terminal 11 is input to the input terminal of an arithmetic amplifier 14 configuring an initial stage amplifier 10. Positive/negative power sources 30 and 31 are connected through impedance elements (for example, resistances) 43 and 44 to the positive/negative power supply terminals +V and -V of the arithmetic amplifier 14 of the initial stage amplifier 10. Furthermore, decoupling capacitors 41 and 42 are serially connected between the positive/negative power supply terminals +V and -V, and the mid-point of connection is connected to the cold end of the input terminal 11. Another arithmetic amplifier 20 configuring a differential amplifier is connected to the post-stage of the initial stage amplifier 10. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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