Patent ID: 7835434

Claim:
An adaptive filter arrangement for filtering first and second sub-carriers from an OFDM encoded carrier signal, the adaptive filter comprising: a low-pass filter configured means to filter first and second sub-carriers, one from another, so as to provide a first output signal, and variable capacitors adapted to modify said low pass filter configured means; and the adaptive filter arrangement comprising: an OFDM encoder for generating a calibration signal under control of a controller; a signal path so that the calibration signal can be applied to the low-pass filter configured means; Fast Fourier Transform means for measuring a response of the first output signal to the calibration signal; and wherein the adaptive filter arrangement is tunable in response to one or more input signals derived from a comparator operable to compare the response of the first output signal to the calibration signal with a desired value, and in response to provide a correction factor for varying a characteristic of the filter.