| 摘要 |
In a power amplifier driven by a pulse width modulation (PWM) signal, a first pair of drive pulses opposite in level to each other is formed from a first pulse width modulation signal whose quantization level corresponds to its pulse width and supplied to a first push-pull circuit ( 15 ). A second pair of drive pulses opposite in level to each other is formed from a second pulse width modulation signal whose two's complement of quantization level corresponds to its pulse width, and supplied to a second push-pull circuit ( 16 ). A speaker ( 19 ) is connected between the first and second push-pull circuits ( 15 and 16 ). A deviation between potentials at the output terminals of the first and second push-pull circuits ( 15 and 16 ), respectively, is detected. When a deviation is detected, the push-pull circuits are substantially stopped from operating.
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