Design of Crystal-Oscillator Frequency Quadrupler for Low-Jitter Clock Multipliers

Abstract

Implementation of low-noise power-efficient clock multipliers requires low-noise high-frequency reference clocks. This paper presents ways to generate such reference clocks at four times the frequency of a standard crystal oscillator (XO) output frequency. Using extensive digital correction techniques, a 216-MHz reference clock with an integrated jitter of 77fsrms is generated from a 54-MHz Pierce XO. A ring oscillator-based injection locking clock multiplier driven by the proposed quadrupler is used to demonstrate the efficacy of the quadrupler. Fabricated in a 65-nm CMOS process, the proposed clock multiplier occupies an active area of 0.16 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and achieves 366fsrms integrated jitter at 4.752-GHz output frequency while consuming 6.5-mW power from a 1.0-V supply of which 1.5 mW is consumed in the quadrupler.