AN ANALOG APPROACH TO COMPENSATE FOR OpAmp OFFSET AND FINITE GAIN IN SC CIRCUITRY: A CASE STUDY OF A CYCLIC RSD ADC

Reinhard Kindt, Richard Ižák

Abstract

Design of high-resolution Nyquist rate A/D converter necessitates the usage of advanced circuit techniques to compensate for arising analog errors. In switched capacitor ADC, besides the well know techniques such as bottom plate sampling, mismatch-independent and redundant (RSD: 1.5 bit/stage) conversion for the elimination of charge injection, capacitor mismatch, comparator and offset sensitivity, respectively, the most utilised circuit techniques are those for OpAmp’s offset and finite gain errors cancellation. An alternative technique for compensation of the errors due to finite gain and offset of Opamp in SC circuits is proposed. This novel method features a charge addition and is compared to so far used approaches based on voltage addition. The concept and the results of a 5 V CMOS implementation of cyclic RSD ADC with ratio-independent SC technique using this correction method are discussed.

Keywords

cyclic/algorithmic analog-digital converter, switched capacitor circuit, amplifier’s finite gain and offset

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IMEKO-TC4-2002-054.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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