Patent ID: 7289782

Claim:
A fractional-N synthesizer comprises: phase and frequency detection module operably coupled to produce a charge up signal, a charge down signal, or an off signal based on at least one of a phase difference and a frequency difference between a reference oscillation and a feedback oscillation; charge pump circuit produces a positive current in response to the charge up signal, a negative current in response to the charge down signal, and zero current in response to the off signal; gated current offset module operably coupled to cyclically provide a gated offset current based on the reference oscillation; loop filter operably coupled to filter at least some of: the positive current, the negative current, the zero current, and the gated offset current to produce a control voltage; voltage controlled oscillator to produce an output oscillation based on the control voltage; and fractional-N divider module operably coupled to divide the output oscillation by a fractional N value to produce the feedback oscillation.