| 摘要 |
PROBLEM TO BE SOLVED: To suppress noise of an audio-signal processing circuit.SOLUTION: A reference bias circuit 30 generates a first reference voltage Vand a second reference voltage V. A first amplifier 10 has an upper-side power-supply terminal receiving a first power-supply voltage Vcc1, and generates a first signal Vthat swings with a central focus on a first bias voltage according to the first reference voltage. A start-up bias circuit 40 generates a start-up bias voltage Von the basis of a second power-supply voltage Vcc2 independent from the first power-supply voltage Vcc1. A selector circuit 50 selects one of the first signal Vand the start-up bias voltage V, and outputs the selected signal as a second signal V. A second amplifier 20 has an upper-side power-supply terminal receiving the second power-supply voltage Vcc2, and non-inverting amplifies the second signal Vwith reference to the second reference voltage Vto generate a third signal V. |
