High performance op amps in a 40V BiCMOS process and their applications

This paper describes the design of three high-performance op amps in a 40V BiCMOS technology. The first circuit is a low-noise op amp with MOS inputs. A thermal noise level as low as with a 1/f noise corner frequency of 100 Hz is achieved. For applications that can tolerate a lower input impedance, a more economical bipolar input low-noise op amp has been designed, yielding an even better noise performance for source impedances up to 20 k. The third circuit is an internally compensated high-gain-bandwidth (GBW=15 MHz) op amp that can drive loads from 0 to 20 pF. A fourth-order low-pass switched-capacitor filter making use of the latter op amp is discussed next. Finally the applications of this 40V BiCMOS process are illustrated.