Abstract
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 structural simplicity approaching that of digital circuits. Ideally, the design tool presented here can be used to optimize gain and CMRR independent of the 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 μm 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 μm×474 μm.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
R. Hogervorst, J. Tero, and J. Huijsing, “Compact CMOS Constant-g m Rail-to-Rail Input Stage with g m -Control by an Electronic Zener Diode.” IEEE J. Solid-State Circuits 31(7), pp. 1035–1040, 1996.
S. Sakurai and M. Ismail, “Robust Design of Rail-To-Rail CMOS Operational Amplifiers for a Low Power Supply Voltage.” IEEE J. Solid-State Circuits 31(2), pp. 146–156, 1996.
T. Saether, et. al., “High Speed, High Linearity CMOS Buffer Amplifier.” IEEE J. Solid-State Circuits 31(2), pp. 255–258, 1996.
J. Eggermont, D. DeCeuster, D. Flandre, B. Gentinne, P. G. A. Jespers, and J-P Colinge, “Design of SOI CMOS Operational Amplifiers for Applications up to 300°C.” IEEE J. Solid-State Circuits 31(2), pp. 181–186, 1996.
K. Bult and G. J. G. M. Geelen, “A Fast-Settling CMOS Op Amp for SC circuits with 90–dB DC Gain.” IEEE J. Solid-State Circuits 25(6), pp. 1379–1384, 1990.
K. Bult and G. J. G. M. Geelen, “The CMOS Gain-Boosting Technique.” Analog Integrated Circuits and Signal Processing 1(2), pp. 119–135, 1991.
A. Sedra and K. Smith, Microelectronic Circuits. 3rd edn. Chicago: Holt, Rinehart and Winston, 1994.
M. Ismail and T. Fiez, Analog VLSI: Signal and Information Processing. New York: McGraw-Hill, 1994.
H. Abel-Aty-Zohdy, “Diverse Projects Design-Experiences in Analog/Digital Microelectronic Systems.” Proceedings of IEEE Computer Society, International Conference on Microelectronics Systems Education, MSE 97, pp. 43–44, 1997.
H. S. Abdel-Aty-Zohdy and F. EI. Licy, “OCT TOOLS: A Complete Design Project.” Oakland University Technical Report, ESE 94–7–2, 1994.
M. Bazes, “Two Novel Fully Complementary Self-Biased CMOS Differential Amplifiers.” IEEE J. Solid-State Circuits 26(2), pp. 165–168, 1991.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Abdel-Aty-Zohdy, H.S., Purcell, J. Compact High Gain CMOS Op Amp Design using Comparators. Analog Integrated Circuits and Signal Processing 19, 139–144 (1999). https://doi.org/10.1023/A:1008345630252
Issue Date:
DOI: https://doi.org/10.1023/A:1008345630252