Gain controller using switched capacitors

摘要

A gain controller using switched capacitors is provided. The gain controller is operable in a sampling mode or an amplifying mode and controls the gain of an analog input signal. The gain controller includes an operational amplifier, input capacitors, a feedback capacitor, and switches. The operational amplifier controls the gain of the analog input signal and generates an output signal having the controlled gain. The input capacitors are connected to the input side of the operational amplifier in parallel. The feedback capacitor is connected between the input side and the output side of the operational amplifier. The switches connect at least one of the input capacitors to the input signal or a reference voltage, in response to the kinds of operation modes and a predetermined externally applied digital gain control signal. According to the gain controller using switched capacitors, it is possible to automatically control the gain of an input signal at high speed and to reduce power consumption since the time required for settling the gain of the input signal to a desired value is short.