Track and hold amplifiers and digital calibration for analog-to-digital converters

Abstract

An exemplary differential track and hold amplifier includes a track stage including first and second linearized pairs connected in series at their respective inputs and in parallel at their respective outputs. The differential track and hold amplifier also includes a hold stage selectively coupled to the outputs of the first and second linearized pairs. The hold stage includes a unity gain buffer with feedback having a hold capacitor interconnected across its outputs. The differential track and hold amplifier also includes an output buffer coupled to the outputs of the hold stage. An exemplary analog-to-digital converter includes a differential track-and-hold amplifier, a voltage ladder, and a plurality of slices. Each of the slices in turn includes a differential preamplifier coupled to the track-and-hold amplifier and to a corresponding location on the voltage ladder; a current mode logic latch comparator coupled to the differential preamplifier; a large-swing latch coupled to the current mode logic latch comparator; a complementary metal oxide semiconductor latch having a dummy load; a calibration digital to analog converter connected across outputs of the differential preamplifier to inject calibration currents; and a register coupled to the calibration digital to analog converter and storing calibration values for use thereby. The analog-to-digital converter also includes a multiplexer which multiplexes outputs of the complementary metal oxide semiconductor latches down to a predetermined number of outputs.