Switched‐capacitor realization of a fourier analyzer using integral feedback capacitance circuit

Abstract The technique of forming a discrete Fourier transform (DFT) circuit with an analog circuit has numerous attractive features not available in the DFT circuit with a digital circuit. For example, frequency analysis can easily be carried out and real time processing is possible. The switched‐capacitor (SC) circuit has recently been considered suited for MOSIC of analog circuits. In this paper, a DFT circuit is constructed with an SC circuit in an analog format so that circuit integration is possible. For SC realization of a DFT circuit, an integral feedback capacitance circuit has been proposed for a signal processing circuit. This circuit makes use of the feedback capacitance terminal voltage of an integrator made of an operational amplifier. It is used for the SC sample‐and‐hold circuit and the SC multiplier and adder. This SCDFT circuit has been fabricated with discrete components and the operating principle has been confirmed.