25.3 GHz, 4.1 mW VCO with 34.8% tuning range using a switched substrate-shield inductor

A wide tuning range CMOS VCO based on a switched substrate-shield inductor is presented. The proposed VCO uses a high quality factor, switchable inductor with smaller parasitics for frequency tuning range extension. Inductance is switched by controlling the eddy currents in a modified, floating substrate-shield. Using the proposed design, a 29 % inductance switching is achieved while maintaining a high quality factor of > 15.5. The prototype VCO shows an excellent frequency tuning range of 34.8 % and a phase noise of −120.1 dBc/Hz at 10 MHz offset for 25.3 GHz carrier frequency. This VCO has a FOMT of 192.1±2.5 dBc/Hz across the tuning range with only 4.1 mW power consumption.

I. Introduction

V-band (57–66 GHz) is readily used for the high data-rate, short-range applications (for e.g. Wireless LAN, Wireless PAN, WiGig etc.). Due to the mobile nature of such applications, ultra-low power consumption is a key requirement. RF-frontend power in mm-wave systems can be significantly reduced by using system optimizations such as sub-harmonic carrier routing or a super-heterodyne transceiver architecture [1] – [2]. These methods require a VCO with wide frequency tuning range (FTR). Among many possible methods, ultra-low power mm-wave VCO design faces two major challenges: smaller varactor based FTR due to higher parasitic capacitance (C_p) at the LC-tank, and poor phase noise (PN) due to the degraded high-frequency quality factor (Q) of the varactor (Qv) [3]–[5].