Design of an A/D converter using complementary three-input amplifiers

The authors present a technique that allows the implementation of analog-to-digital converters using mainly active components. While total elimination of passive components is not possible, they have successfully removed the need for linear and well-matched ones. Capacitors in their circuits are solely for the purpose of voltage storage; the precision of voltage scaling is totally dependent on the matching of active components. While the resistive-ladder technique requires the matching of 2^N resistors, the technique introduced here requires matching only of MOSFETs in groups of four, one group for each amplifier used. Any improvements in active-device technologies will naturally lead to improvement in the performance of circuits described here