A Replica-Amp Gain Enhancement Technique for an Operational Amplifier with Low Mismatch Sensitivity and High Voltage Swing

Junya MATSUNO  Masanori FURUTA  Tetsuro ITAKURA  Tatsuji MATSUURA  Akira HYOGO  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E99-A   No.2   pp.547-554
Publication Date: 2016/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E99.A.547
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuit Techniques and Related Topics)
Category: 
Keyword: 
opamp,  gain enhancement,  replica amplifier,  

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Summary: 
A new gain enhancement technique for an operational amplifier (opamp) using a replica amplifier is presented to reduce a sensitivity of a gain mismatch between the main amplifier and the replica amplifier which limits a gain-enhancement factor in the conventional replica-amp techniques. In the proposed technique, the replica amplifier is used to only amplify an error voltage of the main amplifier. The outputs of the main amplifier and the replica amplifier are added to cancel the error voltage of the main amplifier. The proposed technique can also achieve a higher output voltage swing because the replica amplifier amplifies only the error voltage. In case of using a fully-differential common-source opamp for the main amplifier and a telescopic opamp for the replica amplifier, Monte Carlo simulation at 100 iterations shows that the proposed amplifier has almost the same gain variation with 15.5dB gain enhancement and about five times output voltage swing expanding for a supply voltage of 1.2V compared with the single closed-loop amplifier using the telescopic opamp.