SHOCK SOUND SUPPRESSION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To achieve preferred suppression of shock sound when switching on a BTL (Balanced Transformer Less) system speech amplifier. SOLUTION: The BTL system speech amplifier includes inverting amplifier circuits 52 and 54. The inverting amplifier circuit 52 in which audio signals passing through a capacitor CINare inputted to output inverting signals to an end of a speaker 12 starts operation thereof at the same time as when switching on the speech amplifier. On the other hand, the inverting amplifier circuit 54 in which the inverting signals are inputted to output non inverting signals to the other end of the speaker 12 turns to be on and off. This prevents reproduction of the shock sound from the speaker 12 caused by the voltage between input terminals of an operational amplifier 10 not in operation when turning on a power supply in response to the difference between DC level of CINbeing charged and reference voltage VREF. COPYRIGHT: (C)2009,JPO&INPIT