BiCMOS vs. CMOS Operational Amplifiers for High-Speed Pipelined A/D Converters

This paper presents a comparison between BiCMOS and CMOS op-amps to be employed in pipelined analog-to-digital converters. Single and two-stage architectures were considered; in addition, a couple of op-amps exploiting bipolar devices in the input stage are proposed. The amplifiers were designed for the first stage of a 12-b high-speed converter; op-amps are constrained by a fixed power budget and are compared in terms of the error due to their finite DC-gain and incomplete settling.