设计了一种基于0.5μm CMOS工艺的增益可控音频前置放大器电路。该电路采用直流音量控制方式控制前置放大器的增益,进而实现整体音频放大器的音量控制。外部输入的直流模拟电压经过片内模数转换器转换成数字控制信号,控制前置放大器的输入电阻与反馈电阻的比值,从而实现前置放大器的增益控制。该放大器能够实现32档的音量控制范围,增益从-50 dB变化到25 dB,电路版图面积为1.2 mm×0.8 mm。 A gain-controllable audio preamplifier circuit based on a 0.5μm CMOS process is designed. The circuit uses direct current volume control to control the gain of the preamplifier to achieve volume control of the overall audio amplifier. External input DC analog voltage through the on-chip analog-to-digital converter to convert the digital control signal to control the preamplifier input resistance and the ratio of the feedback resistor in order to achieve preamplifier gain control. The amplifier offers 32-level volume control with variable gain from -50 dB to 25 dB and circuit layout footprint of 1.2 mm × 0.8 mm.