Multi-loop signal processing

A method of processing a signal using a signal processing circuit that comprises a first signal loop comprising a bandpass filter and a first feedback path that extends around the bandpass filter such that the first signal loop comprises a passband, a signal processing block downstream of the bandpass filter, and a second feedback path that extends from downstream of the signal processing block to upstream of the bandpass filter, the method comprising the steps of:

• causing the first signal loop to generate a filtered signal in the passband;
• processing the filtered signal using the signal processing block downstream of the bandpass filter such that an output signal is conditioned at an output downstream of the bandpass filter.

A signal processing circuit for a digital communication device, comprising:

• an outer signal loop comprising an input, an output, and a transformation block adapted to perform a signal transformation operation on a signal being processed;
• and
• an inner signal loop comprising a tunable bandpass filter, the inner signal loop being nested within the outer signal loop such that the tunable bandpass filter is connected within each of the inner signal loop and the outer signal loop, and the transformation block is connected outside the inner signal loop.