Operational Transconductance Amplifier with Rail-to-Rail Input Stage Using Single Channel Type MOSFETs

Takahide SATO  Shigetaka TAKAGI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E85-A   No.2   pp.354-359
Publication Date: 2002/02/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
rail-to-rail operation,  OTA,  MOSFET,  operation region,  

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This paper proposes a novel method to realize an input stage for a rail-to-rail operational transconductance amplifier (OTA). The proposed input stage consists of single channel type MOSFETs. Therefore no matching is necessary between n-channel MOSFETs and p-channel MOSFETs unlike conventional methods. The proposed input stage is composed of three MOSFETs which operate in plural operation regions. Nevertheless a combination of drain currents of the three MOSFETs is proportional to an input voltage which varies between two power-supply rails. A circuit configuration to realize a rail-to-rail OTA with the proposed input stage is also proposed. The operation principle and the validity of the proposed circuit are confirmed through HSPICE simulations.