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Iterative filter circuit calibration

  • US 7,761,067 B1
  • Filed: 04/21/2004
  • Issued: 07/20/2010
  • Est. Priority Date: 05/15/2003
  • Status: Expired due to Fees
First Claim
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1. A filter calibration circuit, consisting of:

  • a DC voltage source operable to produce a reference amplitude signal;

    an amplitude detector configured to receive an output signal from a variable gain stage and produce an amplitude signal, wherein the output signal from the variable gain stage is produced by modifying an amplitude of an output signal produced by a filter circuit, which comprises capacitive components to be calibrated to a desired frequency;

    a comparator operable to generate a comparator output based on the amplitude signal of the amplitude detector and the reference amplitude signal of the DC voltage source; and

    a calibration logic unit, separate from the comparator, operable toreceive the comparator output,produce a digital gain code based on the comparator output to adjust a gain of the variable gain stage, andproduce a digital component code corresponding to switches associated with the capacitive components in the filter circuit to be used by the filter circuit in adjusting a combined value of the capacitive components in the filter circuit by selectively turning on or off one or more of the switches associated with the capacitive components to control a number of the capacitive components active in the filter circuit to calibrate the filter circuit to the desired frequency.

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