DELTA-SIGMA-MODULATION IN FRACTIONAL-N FREQUENCY-SYNTHESIS

This paper describes a delta-sigma (DELTA-SIGMA) modulation and fracti onal-N frequency division technique to perform indirect digital freque ncy synthesis based on the use of a phase-locked loop (PLL). The use o f DELTA-SIGMA modulation concepts results in a beneficial noise shapin g of the phase noise (jitter) introduced by fractional-N division. The technique has the potential to provide low phase noise, fast setting time, and reduced impact of spurious frequencies when compared with ex isting fractional-N PLL techniques.