Cmos
1508
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS, VOL. 52, NO. 8, AUGUST 2005
Design Procedure for Two-Stage CMOS Opamp With Flexible Noise-Power Balancing Scheme
Jirayuth Mahattanakul, Member, IEEE, and Jamorn Chutichatuporn
Abstract—This paper presents a basic two-stage CMOS opamp design procedure that provides the circuit designer with a means to strike a balance between two important characteristics in electronic circuit design, namely noise performance and power consumption. It is shown in this paper that, unlike the previously reported design procedures, the proposed design step allows opamp designers to trade between noise performance and power consumption with greater flexibility. In order to verify the viability of the proposed design step, SPICE simulation results of the opamp designed by the proposed procedure, under a variety of temperature and process conditions, are given. Index Terms—CMOS analog integrated circuits, frequency compensation, operational amplifier, poles and zeroes.
Fig. 1. Basic two-stage CMOS opamp.
I. INTRODUCTION MOS opamps are ubiquitous integral parts in various analog and mixed-signal circuits and systems. The two-stage CMOS opamp shown in Fig. 1 is widely used because of its simple structure and robustness. In designing an opamp, numerous electrical characteristics, e.g., gain-bandwidth, slew rate, common-mode range, output swing, offset, all have to be taken into consideration. Furthermore, since opamps are designed to be operated with negative-feedback connection, frequency compensation is necessary for closed-loop stability. Unfortunately, in order to achieve the required degree of stability, generally indicated by phase margin, other performance parameters are usually compromised. As a result, designing an opamp that meets all specifications needs a good compensation strategy and design methodology. The simplest frequency compensation technique employs the across Miller effect by connecting a
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS, VOL. 52, NO. 8, AUGUST 2005
Design Procedure for Two-Stage CMOS Opamp With Flexible Noise-Power Balancing Scheme
Jirayuth Mahattanakul, Member, IEEE, and Jamorn Chutichatuporn
Abstract—This paper presents a basic two-stage CMOS opamp design procedure that provides the circuit designer with a means to strike a balance between two important characteristics in electronic circuit design, namely noise performance and power consumption. It is shown in this paper that, unlike the previously reported design procedures, the proposed design step allows opamp designers to trade between noise performance and power consumption with greater flexibility. In order to verify the viability of the proposed design step, SPICE simulation results of the opamp designed by the proposed procedure, under a variety of temperature and process conditions, are given. Index Terms—CMOS analog integrated circuits, frequency compensation, operational amplifier, poles and zeroes.
Fig. 1. Basic two-stage CMOS opamp.
I. INTRODUCTION MOS opamps are ubiquitous integral parts in various analog and mixed-signal circuits and systems. The two-stage CMOS opamp shown in Fig. 1 is widely used because of its simple structure and robustness. In designing an opamp, numerous electrical characteristics, e.g., gain-bandwidth, slew rate, common-mode range, output swing, offset, all have to be taken into consideration. Furthermore, since opamps are designed to be operated with negative-feedback connection, frequency compensation is necessary for closed-loop stability. Unfortunately, in order to achieve the required degree of stability, generally indicated by phase margin, other performance parameters are usually compromised. As a result, designing an opamp that meets all specifications needs a good compensation strategy and design methodology. The simplest frequency compensation technique employs the across Miller effect by connecting a
References: [1] P. E. Allen and D. R. Holberg, CMOS Analog Circuit Design. New York: Oxford Univ. Press, 2002. [2] G. Palmisano, G. Palumbo, and S. Pennisi, “Design procedure for two-stage CMOS transconductance operational amplifiers: A tutorial,” in Analog Integrated Circuits and Signal Processing. Norwell, MA: Kluwer, 2001, vol. 27, pp. 179–189. [3] P. Gray, P. Hurst, S. Lewis, and R. Meyer, Analysis and Design of Analog Integrated Circuits. New York: Wiley, 2001. [4] D. A. Johns and K. Martin, Analog Integrated Circuit Design. New York: Wiley, 1997. [5] G. Palmisano and G. Palumbo, “An optimized compensation strategy for two-stage CMOS opampS,” IEEE Trans. Circuits Syst. I, Fundam. Theory Appl., no. 3, pp. 178–182, Mar. 1995. [6] R. J. Baker, H. W. Li, and D. E. Boyce, CMOS Circuit Design, Layout, and Simulation. New York: Wiley Interscience, 1998. Jirayuth Mahattanakul (S’91–M’98) was born in Bangkok, Thailand, in 1968. He received the B.Eng. degree from King Mongkut’s Institute of Technology, Bangkok, Thailand, the M.S. degree from Florida Institute of Technology, Melbourne, and the Ph.D. degree from Imperial College London, London, U.K., in 1990, 1992, and 1998, respectively, all in electrical engineering. From 1992 to 1994, he was with TelecomAsia, Bangkok, Thailand, in the Network Planning and Engineering Division. In 1994, he joined Mahanakorn University of Technology, Bangkok, Thailand, where he is currently a Dean of Graduate School and an Associate Professor of Electronic Engineering. Dr. Mahattanakul was a member of the Executive Committee of the Engineering Institute of Thailand and is a committee of the IEEE Circuits and Systems Chapter—Thailand Section. Jamorn Chutichatuporn was born in Cholburi, Thailand, in 1977. He received the B.Eng. and the M.Eng. degrees in electronic engineering from Mahanakorn University of Technology in 2000 and 2002, respectively. From 2003 to 2004, he was with Delta Electronics (Thailand) Public Company Limited, Samutprakarn, Thailand, in the R&D Division. Since 2004, he joined RGY Hydraulic Company, Cholburi, Thailand, where he is currently a General Manager. Authorized licensed use limited to: AMITY University. Downloaded on November 16, 2009 at 05:58 from IEEE Xplore. Restrictions apply.