This paper discusses the design of high gain, general purpose op amps. The
op amp is based on a novel cascaded design using comparators and with struc
tural simplicity approaching that of digital circuits. Ideally, the design
tool presented here can be used to optimize gain and CMRR independent of th
e other op amp performance parameters. The designed op amp has 140 dB open-
loop gain and 43 MHz unity gain frequency (GBW) in Berkeley Spice3f Level-2
simulation. The circuit is implemented using a 2.0 mu m nwell CMOS process
through MOSIS. The op amp is self-biased and requires only power supplies
of +/- 2.5 V. It occupies an area of 113 mu m x 474 mu m.