MASH-Based Divider Controllers for Mitigation of Wandering Spurs in a Fractional-N Frequency Synthesizer

The divider controller can contribute significantly to the phase noise and spur pattern in the output of a nonlinear fractional- N frequency synthesizer. A type of time-varying spurs caused by a MASH DDSM divider controller, termed wandering spurs, has been observed in simulations and measurements of real synthesizers. In this work, we propose and analyze several MASH-based divider controller architectures that mitigate wandering spurs in a fractional-N frequency synthesizer.