An 18–19.2 GHz Voltage-Controlled Oscillator with a Compact Varactor-Only Capacitor Array

Abstract

This paper presents a K-band CMOS cross-coupled pair voltage-controlled oscillator (VCO) that utilizes the varactor-only capacitor network. The proposed circuit features low parasitics and a compact capacitor network, such that the varactor in the analog tuning path directly affects the oscillation frequency with a large gain of the VCO, and the varactor in the digital tuning path results in minimal noise sources, thus achieving low phase noise for the automotive FMCW radar application. This VCO was designed using TSMC 65 nm technology, and the post-layout simulation results show a stable oscillation across 18–19.2 GHz, a minimum phase noise of −105.9 and −128 dBc/Hz at 1- and 10-MHz offset frequencies while dissipating 21 mW of power from a 1 V supply. Furthermore, no notable variations in phase noise are observed across the oscillation frequency tuning range. It reveals a figure of merit (FOM) of −178.3 dBc/Hz while using a varactor-only capacitor array and occupying a small chip area.

Design of an Active-Loaded Differential Voltage-Controlled Oscillator (VCO) Using Double-Gate MOSFET

“…This can be avoided by utilising measures to control the supply voltage, preventing any fluctuation (an increase or decrease), and ensuring the control voltage of the resonator circuit is broad. Frequency pushing can cause substantial degradation in phase noise, given that the circuit will also be easily affected by power-supply noise [5]; • Varactor-related effects -This component is essential to the operation of the VCO. There must be careful attention paid to the tuning gain (which should be reduced to reduce the phase noise of the oscillator) and tuning voltage (a reverse-biased varactor may become forward-biased, but the tuning voltage should never be zero, which will seize oscillation) [6].…”

Cost-Efficient Two-Level Modeling of Microwave Passives Using Feature-Based Surrogates and Domain Confinement

“…EM analysis is being used throughout the entire design cycle of microwave devices and systems, starting from topology development [1][2][3][4] through parametric studies [5], to the final refinement of circuit dimensions [6][7][8][9][10][11]. This is primarily because EM analysis is able to accurately account for various phenomena exerting significant effects on circuit responses, such as EM cross-coupling [12][13][14][15][16][17]. Furthermore, the incorporation of size reduction techniques of various kinds (e.g., use of the slow-wave phenomenon [18][19][20][21], transmission line folding [22,23], defected ground structures [24,25], or multi-layer realizations [26][27][28]) makes the topologies of microwave devices increasingly intricate.…”