| 摘要 |
PURPOSE:To attain the circuit operation at a lower voltage by decreasing a voltage drop of a ripple filter. CONSTITUTION: A ripple filter circuit 3' is used to supply power to a prestage 4 of a low frequency amplifier circuit and is constituted to extract a voltage proportional to a power supply voltage. Then, a ripple filter circuit 2' supplying a stabilized DC voltage eliminated with ripple to the filter 3' and a circuit 1 other than a low frequency amplifier section is constituted by using a capacitor 39. Thus, the voltage drop of the ripple filters 2', 3' is decreased so as to activate the circuits at a lower voltage, resulting that the operating point of the low frequency circuit is brought to an operating point at which a maximum output is obtained independently of an input voltage. Since a capacitor 39 is used in common to the circuits 2', 3', the number of externally mounted components for circuit integration is decreased.
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