Patent ID: 7761067

Claim:
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 to receive the comparator output, produce a digital gain code based on the comparator output to adjust a gain of the variable gain stage, and produce 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.