Delta-sigma modulation in fractional-N frequency synthesis

Abstract

A description is given of a delta-sigma ( Delta - Sigma ) modulation and fractional-N frequency division technique for performing indirect digital frequency synthesis using a phase-locked loop (PLL). The use of Delta - Sigma modulation concepts results in beneficial shaping of the phase noise (jitter) introduced by fractional-N division. The technique has the potential to provide low phase noise, fast settling time, and reduced impact of spurious frequencies when compared with existing fractional-N PLL techniques.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>