| 摘要 |
In an amplifying circuit, a first and a second switches are provided between an input terminal and output terminal of coupling capacitor and amplifier, and these switches are set in OFF state in a power-down state, and the second switch is turned on for a specified period when changed over to ordinary operation, and the capacitor is charged to a bias voltage corresponding to direct-current operating point, and then the second switch is turned off, and the first switch is turned on, and the mode is shifted to the ordinary operating state. Therefore, in a power-down state, a popping noise can be suppressed without resort to a charger for preliminarily charging the capacitor in a power-down state, and increase of current consumption due to charger is eliminated.
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