A 4.4-5.4GHz digital fractional-N PLL using ΔΣ frequency-to-digital converter

Abstract

A phase interpolator (PI) based fractional divider is used to improve the quantization noise shaping properties of a 1-bit ΔΣ frequency-to-digital converter (FDC). Fabricated in 65nm CMOS process, the prototype calibration-free fractional-N Type-II PLL employs the proposed FDC in place of a high resolution TDC and achieves-102dBc/Hz in-band phase noise and 852fsrms integrated jitter (1k-40M) while generating 5.054GHz output from 31.25MHz input. © 2014 IEEE.