A /spl Delta//spl Sigma/ fractional-N frequency synthesizer with a multi-band PMOS VCOs for 2.4 and 5GHz WLAN applications

This paper presents a fully integrated multi-band frequency synthesizer architecture. The synthesizer is a /spl Delta//spl Sigma/ based fractional-N frequency synthesizer with three on-chip LC tuned VCOs to cover the entire frequency bands specified in IEEE802.11b, and 802.11a WLAN standards. The synthesizer includes a /spl Delta//spl Sigma/ shaper, a dead-zone-free phase frequency detector and a fully differential charge pump. The measured in-band phase noise is lower than -93dBc/Hz and the VCO out of band phase noise is -120dBc/Hz at 1MHz offset.