The main purpose of the input stage of an operational amplifier is to amplify differential signals and to reject common-mode input voltages. An important specification of an input stage is the common-mode input range. If the common-mode voltage is kept within this range, the input stage will properly respond to small differential signals. Hence, an application has to be designed such that the common-mode input voltage stays within the common-mode input range. Other important specifications of the input stage are the input referred noise, offset and the common-mode rejection ratio.
KeywordsTail Current Current Mirror Input Stage Strong Inversion Current Switch
Unable to display preview. Download preview PDF.
- P.R. Gray and R.G. Meyer, “Analyses and Design of Analog Integrated Circuits”, Wiley, New York, USA, 1984.Google Scholar
- P.E. Allen, D.R. Holberg, “CMOS Analog Circuit Design”, Holt, Rinehart and Winston, Inc., Fort Worth, USA, 1987.Google Scholar
- J.H. Huijsing, “Integrated Circuits for Accurate Linear Analogue Electrical Signal Processing”, Ph.D. dissertation, Delft University of Technology, Delft, The Netherlands, 1981.Google Scholar
- Y. Chang, W. Sansen, “Low-Noise Wide Band Operational Amplifiers in Bipolar and CMOS Technologies”, Kluwer Academic Publishers, Boston, USA, 1991.Google Scholar
- R.F. Wassenaar, J.H. Huijsing, R.J. Wiegerink, R. Hogervorst and J.P. Tero, “Differential amplifier having rail-to-rail input capability and square root current control”, US patent, patent no. 5,371,474, December 6, 1994.Google Scholar
- J.H. Huijsing, R. Hogervorst, “Rail-to-Rail Input Stages with Constant gm and Constant Common-Mode Output Currents”, US patent application, Appl. no. 08/625,458, filed March 29, 1996.Google Scholar
- J.H. Huijsing, R. Hogervorst, J.R Tero, “Compact CMOS Constant-gm Rail-to-Rail Input Stages by Regulating the Sum of the Gate-Source Voltages Constant”, US patent application, Appl. no. 08/ 523, 831, filed September 6, 1995.Google Scholar
- R. Hogervorst, J.R Tero, J.H. Huijsing, “Compact CMOS constant-gm rail-to-rail input stage with gm control by an electronic zener diode”, Proceedings ESSCIRC 1995, Lille, France, 19–21 September 1995, pp. 78–81.Google Scholar
- R. Hogervorst, J.H. Huijsing, J.R Tero, “Rail-to-rail input stages with gm control by multiple input stages”, US patent application, Appl. no. 08/430,517, filed April 27, 1995.Google Scholar
- R. Hogervorst, S.M. Safai, J.R Tero, J.H. Huijsing, “A Programmable 3-V CMOS Rail-to-Rail Opamp with Gain-Boosting for Driving Heavy Resistive Loads”, Proceedings IEEE International Symposium on Circuits and Systems, Seattle, USA, April 30-May 3 1995, pp. 1544–1547.Google Scholar