A 52 GHz frequency synthesizer featuring a 2nd harmonic extraction technique that preserves VCO performance

Abstract

This paper introduces a 2nd harmonic extraction technique and its implementation in a 46.4-58.1 GHz frequency synthesizer. The frequency doubling approach is based on tapping second harmonic signals at the VCO supply and tail nodes and amplifying them to provide a differential output. Since the amplifiers do not load the VCO outputs, the proposed technique does not affect either the tuning range or the frequency of the VCO. Moreover, a novel noise bypass technique is utilized to ensure that the amplifiers do not degrade the VCO phase noise. As a result, the frequency synthesizer achieves 22.4% tuning range (46.4-58.1 GHz) and phase noise below -118 dBc/Hz while consuming 66 mW from a 1 V supply. The stacked common gate amplifier can also be utilized for voltage regulation, providing a relatively constant FOM performance over a 2X power dissipation range. The synthesizer occupies 0.6 mm × 1 mm in IBM 32 nm SOI CMOS.