| 摘要 |
PURPOSE:To minimize the influence of the bias current of a differential amplifier as an inversion-noninversion switching circuit upon its output and to obtain high accuracy by switching the differential amplifier which uses an operational amplifier in synchronism with the change of the polarity of an input signal. CONSTITUTION:An analog switch 13a is connected to its upper terminal as shown by a solid line and an analog switch 13b is connected to its right-side terminal, so that the differential amplifier 10 operates as an inverting amplifier whose gain is -1. Further, the analog switch 13a is connected to the lower terminal and the analog switch 13b is connected to the left-side terminal, so that the amplifier becomes a noninverting amplifier whose gain is 1. Namely, the input analog signal V1 is inputted to a polarity detector 14, which outputs an analog switch control signal d0 synchronized with the change of the polarity of the input analog signal V1. Then, the connections of the analog switches 13a and 13b are so controlled with the analog switch control signal d0 that the polarity of the input analog signal V1 is uniform, thereby switching the differential amplifier 10 between the inverting amplifier and noninverting amplifier. |
