Direct conversion receiver using a dithered local oscillator to mitigate adjacent channel coherent interference

A direct conversion quadrature receiver, comprising:

• a primary local oscillator (LO) that down-converts a received RF signal to a quadrature intermediate frequency (IF) signal;
• and
• a dithering controller responsive to said quadrature IF signal generated by said primary LO for communicating a feedback signal back to said primary LO, said feedback signal controlling an oscillation frequency of said primary LO, the dithering controller comprising
• a filter bank comprising one or more I signal component filters and one or more Q signal component filters, said filter bank generates a plurality of frequency spectra from said quadrature IF signal,
• an interferer level detector that measures each frequency spectra of said plurality of frequency spectra,
• a frequency discriminator that generates a frequency number for each spectra output from said filter bank, and
• a level/frequency threshold including a predetermined power threshold that compares a signal power of each frequency spectra to said predetermined power threshold, wherein said level/frequency threshold provides a step-required output to said LO dithering controller if a frequency spectra of said plurality of frequency spectra exceeds said predetermined power threshold;
• wherein said dithering controller offsets down-conversion of said RF signal by said primary LO from a zero-IF in order to reduce a phase and gain error of said quadrature IF signal.