Chopper stabilization of analog multipliers, variable gain amplifiers, and mixers

  • Godoy P
  • Dawson J
  • 31

    Readers

    Mendeley users who have this article in their library.
  • 9

    Citations

    Citations of this article.

Abstract

We describe a general offset-canceling architecture for analog multiplication using chopper stabilization. Chopping is used to modulate the offset away from the output signal where it can be easily filtered out, providing continuous offset reduction which is insensitive to drift. Both square wave chopping and chopping with orthogonal spreading codes are tested and shown to reduce the offset down to the microvolt level. In addition, we apply the nested chopping technique to an analog multiplier which employs two levels of chopping to reduce the offset even further. We discuss the limits on the performance of the various chopping methods in detail, and present a detailed analysis of the residual offset due to charge injection spikes. An illustrative CMOS proto- type in a 0.18 mprocess is presented which achieves a worst-case offset of 1.5 V. This is the lowest measured offset reported in the DC analog multiplier literature by a margin of two orders of magnitude. The prototype multiplier is also tested with AC inputs as a squarer, variable gain amplifier, and direct-conversion mixer, demonstrating that chopper stabilization is effective for both DC andACmultiplication. The ACmeasurements showthat chopping removes not only offset, but also I noise and second-order harmonic distortion.

Author-supplied keywords

  • Analog multiplier
  • Chopper stabilization
  • Mixer
  • Offset cancellation
  • Variable gain amplifier

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Get full text

Authors

  • Philip Godoy

  • Joel L. Dawson

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free