Analysis of switched-capacitor networks using general- purpose circuit simulation programs

Abstract

This paper presents a method for the analysis of switched-capacitor (SC) networks in the frequency and time domains by the use of general-purpose circuit simulation programs such as SPICE. It is shown how the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</tex> -domain equivalent circuit can be modeled exactly in the continuous-time domain using the lossless transmission line element of the simulation program to implement the required one-port storage element (storistor). The resulting continuous-time equivalent circuit retains the sample-data characteristics of the SC networks and is not restricted to frequencies below the Nyquist rate. It is also shown that the transmission line element can be used to simulate the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(\sin x)/x</tex> effect on the frequency response of the SC network due to the sample-and-hold process. Examples of the simulation of simple SC networks with and without op amps using SPICE are given.