Offset- and gain-compensated track-and-hold stages

A class of new fully-differential track-and-hold stages is presented. The gain of the stages does not depend on capacitor matching, and a predictive correlated-double-sampling scheme is used to reduce the effects of op-amp offset and finite dc gain. A prototype chip was fabricated in a 1.2 μm double-poly double-metal CMOS process. Measured results indicated that the proposed track-and-hold stage is superior in both speed and accuracy to other commonly used CMOS sample-and-hold stages implemented on the same chip