Patent ID: 7171183
Filing Date: 2007-01-30
Classification: H03L

Abstract:
1. A linearized fractional-N synthesizer comprises: phase and frequency detection module operably coupled to receive a reference oscillation and 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 the reference oscillation and a feedback oscillation; charge pump circuit operably coupled, to produce a positive current when the charge up signal is received, a negative current when the charge down signal is received, and a non-zero offset current when the off signal is received, the charge pump circuit to produce the non-zero offset current when the off signal is received and to combine the positive current or the negative current with the non-zero offset current when the charge up signal or the charge down signal is respectively received, the non-zero offset current to have a substantially constant non-zero current value to establish an offset at an output node of the charge pump circuit to shift a response of the charge pump circuit to operate the charge pump circuit in a linear region, wherein the charge pump circuit includes: loop filter operably coupled to produce a control voltage at the output of the charge pump circuit based on at least some of: the positive current, the negative current, and the non-zero offset current; voltage controlled oscillator to produce an output oscillation based on the control voltage; and fractional-N divider module operably coupled to divided the output oscillation by a fractional N value to produce the feedback oscillation.