Performance analysis of sampling switches in voltage and frequency domains using Volterra series

In any data converter system, the linearity of the sampling switch is a very critical parameter, especially for wideband sigma-delta modulators. Distortion introduced in the sampling instance directly degrades the quality of the input signal. In this paper we present analyses of a set of sampling switches in the frequency and voltage domains in order to find the most linear type for wide baseband excitation. Volterra series analysis is adopted to find the frequency behavior of the switches. The theoretical results are verified by circuit simulations in a 0.35 μm CMOS process. It is found that the bootstrap sampling switch is a very attractive candidate, especially for frequencies near f_s/2.