Abstract

Track-and-Hold (T&H) circuits are used in a variety of applications. Noise is a key parameter in a T&H and can be traded for settling time or power consumption. The classical T&H noise design methodology considers only white noise sources, neglecting low-frequency noise sources. Although low-frequency noise contributions have been analyzed in the literature, an insightful, design-oriented analysis for flicker noise that can also be extended for arbitrary noise sources has not been proposed yet. In this brief we present a time-domain noise analysis for a charge-redistribution T&H circuit. The analysis considers the noise contribution from white and 1/f sources. A design-oriented expression to compute the excess noise power due to flicker noise, as a function of the sampling rate, the intended T&H resolution, and the noise parameters, is obtained. This expression shows the dependence of the relative contribution of flicker noise over white noise, on the T&H design parameters. A simplified expression allows one to assess the relative contribution of flicker noise during an early stage of the design flow.