Patent ID: 8046186

Claim:
A method of calibrating a continuous-time filter having at least one adjustable parameter, comprising the steps of: a) providing a square-wave signal; b) filtering the signal with a continuous-time filter having a cutoff frequency less than fs: c) quantizing the filtered signal at the rate fs; d) performing an N-output Fourier transform of the quantized signal into N real output values and N imaginary output values at the rate fs; e) accumulating at least one of the real output values to form a real output signal: f) accumulating at least one of the imaginary output values to form an imaginary output signal; g) summing the real and imaginary output signals to form an output signal: h) squaring the output signal: i) comparing the squared output signal to a comparison value; j) adjusting at least one parameter of the continuous-time filter based upon the comparison: and k) repeating steps a)-j) until the squared output signal is approximately the comparison value; wherein the input signal has a frequency of approximately fs/M, and M is an integer multiple of N.