Patent ID: 8601046

Claim:
A tuning circuit for a continuous-time filter, the tuning circuit coupled to a discrete Fourier transform calculation circuit that calculates an N-point Fourier transform, the discrete Fourier transform calculation circuit having a first input configured to receive an even quadrature sample value and an even phase sample value in a sample period, and a second input configured to receive an odd quadrature sample value and an odd phase sample value in said sample period, the discrete Fourier transform calculation circuit comprising: a counter configured to count the sample periods; an even sample value scaling circuit having a selectable even scaling factor; an odd sample value scaling circuit having a selectable odd scaling factor; a first adder configured to sum the scaled even and odd quadrature sample values; a second adder configured to sum the scaled even and odd phase sample values; a first accumulator configured to accumulate the summed even and odd quadrature sample values; and a second accumulator configured to accumulate the summed even and odd phase sample values; wherein N is selectable and is either 3 or 4, the even and odd scaling factors are selectable based upon the value of N and the value of the sample period count, and wherein when N is set to 3, the counter counts 3 sample periods, and wherein when N is set to 4, the counter counts 2 sample periods, wherein the tuning circuit is configured to employ the summed even and odd quadrature sample values accumulated in the first accumulator and the summed even and odd phase sample values accumulated in the second accumulator to adjust one or more performance characteristics of the continuous-time filter.