Class AB two stage and folded cascode OpAmps based on a squaring circuit

M. R. Valero, Antonio Lopez-Martin, Shanta Thoutam, Jaime Ramirez-Angulo, Ramon G. Carvajal

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

1 Citation (Scopus)

Abstract

This paper presents a novel adaptive bias technique based on the use of squaring circuits. Here, the tail current of an operational amplifier (OpAmp) is controlled using an auxiliary circuit. By design, it generates a well-controlled tail current which - to a first order approximation - is independent of the OpAmp's common-mode input voltage. As a result, parameters like common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) are enhanced. However, when a differential input signal is applied, it generates a tail current proportional to the square of the OpAmp's differential input voltage. In this way, the currents of the OpAmp's input pairs are boosted, thus improving slew rate. Experimental results in 0.5 μm CMOS technology verify current and slew rate enhancement factors between 10 and 15 with less than 20% static current increase.

Original languageEnglish
Title of host publication2015 IEEE International Symposium on Circuits and Systems, ISCAS 2015
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Pages253-256
Number of pages4
ISBN (Electronic)9781479983919
DOIs
Publication statusPublished - 27 Jul 2015
EventIEEE International Symposium on Circuits and Systems, ISCAS 2015 - Lisbon, Portugal
Duration: 24 May 201527 May 2015

Publication series

NameProceedings - IEEE International Symposium on Circuits and Systems
Volume2015-July
ISSN (Print)0271-4310

Conference

ConferenceIEEE International Symposium on Circuits and Systems, ISCAS 2015
CountryPortugal
CityLisbon
Period24/05/1527/05/15

Keywords

  • Class AB Amplifiers
  • CMOS Analog integrated circuits
  • flipped voltage followers
  • low-voltage low power design

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