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用一个电位器把放大器的增益平滑地从正变为负,有时是很有用的。图示电路就有这种功能。运放A1为差动放大器,它的两个输入端是相连的。运放A2为缓冲器。由于R1=R3=R4=R=5kΩ,差动放大器的增益为:
It is sometimes useful to use a potentiometer to smoothly change the gain of the amplifier from positive to negative. The circuit shown has this function. The op amp A1 is a differential amplifier and its two inputs are connected. Amplifier A2 is a buffer. Since R1 = R3 = R4 = R = 5kΩ, the gain of the differential amplifier is: