A Ka-Band Dual-Band Digitally Controlled Oscillator With −195.1-dBc/Hz FoM ${_T}$ Based on a Compact High- $Q$ Dual-Path Phase-Switched Inductor

In this paper, a compact, low-loss, dual-path phase-switched inductor suitable for millimeter-wave (mmWave) transceiver subblocks is proposed. The signal path through the structure is determined by the relative polarity of two differential excitation signals applied to the four-port structure. Because inductance is varied by altering signal path through the inductor, signal-path MOSFET switches are avoided. The inductor, therefore, demonstrates high, mode-invariant quality factor, facilitating the design of high-performance dual-band mmWave transceiver subblocks. Based on the proposed inductor, a dual-band Ka-band oscillator is designed in a 65-nm CMOS technology which covers two frequency bands from 14.8 to 18.7 GHz and from 20.8 to 26.6 GHz. The proposed inductor facilitates a widely tunable, dual-band frequency range while maintaining the state-of-the-art phase noise, power consumption, and figure of merit (FoM). The oscillator achieves measured fractional tuning ranges of 23.3% and 24.5% and phase noise of -115.1 dBc/Hz at 2-MHz offset while consuming only 4.8-mW dc power. A peak tuning-range FoM of -195.1 and -194.9 dBc/Hz is demonstrated across the low-and high-frequency bands.

I. Introduction

With the advent of the 5G era, wideband transceiver hardware design at millimeter-wave (mmWave) frequencies is more important than ever [1]. While spectrum allocation for next-generation cellular has largely focused on a 28-GHz frequency band, expansion is likely to continue into frequency bands ranging across the mmWave spectrum [2]. Furthermore, modern mobile communications’ applications require the use of cellular and ISM frequency bands ranging across single-digit GHz frequencies. The hardware requirements for next-generation wireless and cellular communication present conflicting design challenges of low power operation for mobile applications, excellent noise performance for reliable communication with complex modulation schemes, and modular or frequency reconfigurable designs for compact, low-cost solutions in a dynamic wireless environment with numerous disparate frequency bands [3], [4]. Generation of mmWave local oscillator (LO) signals which meet the requirements of next-generation cellular hardware remains a particularly difficult design challenge.