Digital down converter

A frequency mixer, comprising:

• a low resolution mixer configured to:
• receive a digitized radio frequency signal;
• and
• apply a first down conversion to the radio frequency signal to produce an intermediate frequency signal;
• wherein the low resolution mixer comprises a canonical signed digit (CSD) vector multiplier comprising a plurality of CSD multipliers arranged in parallel to multiply each sample of the digitized radio frequency signal by a plurality of different multiplier values to produce a plurality of product values for each sample of the digitized radio frequency signal.

A multi band frequency down converter, comprising:

• a shared low resolution mixer configured to:
• receive a digitized radio frequency signal;
• and
• apply first down conversions to the radio frequency signal to produce a plurality of intermediate frequency signals;
• a plurality of down conversion channels coupled to the shared low resolution mixer, each of the down conversion channels comprising:
• a decimation filter coupled to the shared low resolution mixer, the decimation filter configured to:
• receive a given one of the intermediate frequency signals;
• and
• reduce a sampling rate of the given one of the intermediate frequency signals to produce a decimated intermediate frequency signal;
• a high resolution mixer coupled to the decimation filter, the high resolution mixer configured to:
• receive the decimated intermediate frequency signal;
• and
• apply a second down conversion to the decimated intermediate frequency signal to produce a down converted signal,
• wherein the high resolution mixer has a frequency resolution that is higher than a frequency resolution of the shared low resolution mixer, and wherein a frequency resolution of a mixer is indicative of how closely spaced consecutive programmable frequencies of the mixer are to each other.