Design Procedure for Three-Stage CMOS OTAs with AC Boosting Frequency Compensation Technique

ABSTRACT

An analytic design guide to design a three-stage cascade CMOS operational amplifier compensated by AC boosting frequency compensation (ACBC) method is presented in this paper. The procedure allows electrical parameters such as gain bandwidth (GBW) product or phase margin to be related to the value of circuit elements such as aspect ratio or biasing currents of transistors. The presented design guide is suited for pencil-and-paper design and yields accurate performance without unnecessary circuit constraint introduction. Simulation results using TSMC 0.18 µm CMOS process verifies accuracy and robustness of proposed procedure. Various load capacitors and circuit conditions are simulated and, based on obtained results, the presented design guide is comprehensive and efficient since it leads us from frequency response parameters to aspect ratio of MOSFETs.

KEYWORDS:

• AC boosting
• CMOS OTA
• Design procedure
• Frequency compensation

ACKNOWLEDGMENTS

The authors thank Sadegh Biabanifard and Mehdi Largani for their help and suggestions.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Iman Chaharmahali

Iman Chaharmahali received the BSc degree in Electrical Engineering from the Islamic Azad University of Borujerd in 2007, and the MSc degree (Hons) in Electronics Engineering from Islamic Azad University, Arak, Iran, in 2010, where he is currently working toward the PhD degree in Electronics Engineering. His research interests include circuit theory, analog circuit design, modelling, and simulation, artificial neural networks and oscillators.

E-mail: [email protected]

Shahrooz Asadi

Shahrooz Asadi received the BSc degree in Electrical Engineering and the MSc degree in Electronics both from Amirkabir University, Tehran, Iran, in 2003 and 2007, respectively, and the PhD degree in Electronics from the School of Information Technology and Engineering (SITE), University of Ottawa, Ottawa, ON, Canada. He joined Shahid Beheshti University in 2011 where he is an assistant professor. His research interests include linear and nonlinear time-domain modelling of millimeter-wave transistors, RF design of active and passive devices, design and optimization of solid-state devices and multiconductor transmission lines and printed circuit board.

E-mail: [email protected]

Massoud Dousti

Massoud Dousti received BS in Electrical Engineering from Orleans University, Orleans, France and MS degrees in Electronics (Microwave and Optics) from Limoges University, Limoges, France, in 1991 and 1994 and PhD in Electronics (Active Microwave Circuits) from University of Paris VI, Pierre et Marie Curie, in 1999, respectively. He served as a teaching assistant in the Department of Electrical Engineering at Ensea, Cergy Pontoise, France from 1998 to 2000. In 2001, he joined the Department of Electrical Engineering of Science and Research branch, Islamic Azad University, Tehran, Iran, where he is now an associate professor. His research interests are linear and nonlinear microwave/RF circuits and systems design, millimeter wave circuits design, and MMIC technology.

E-mail: [email protected]