Fractional-spurs suppression scheme in frequency tracking multi-band fractional-N phase lock loop

摘要

The present invention discusses fractional compensation timing circuitry (15) to track a VCO output frequency, f_O, and provide highly effective error cancellation in a fractional-N PLL synthesizer. This output frequency tracking is used to suppress spurious sidebands, commonly known as spurs, in both fixed-band and multi-band wireless transceiver applications which use fractional-N PLL synthesizers. Some of the critical parameters which benefit from this type of PLL include switching time, phase noise, and reference feed-through.