Design Voltage-Controlled Oscillator using I-MOS Varactor for Selective Tuning for UHF Band Applications

Abstract

To optimize frequency tuning, noise performance, and power efficiency under various process, voltage, and temperature (PVT) conditions, the study investigates the design, implementation, and evaluation of two novel voltage-controlled oscillators (VCOs) for Ultra High Frequency (UHF) applications. The first design is a 180-nm CMOS, five-stage Current-Starved Voltage Controlled Oscillator (CSVCO) with improved tuning via an Inversion mode MOS (I-MOS) varactor. Fine-grained frequency modulation is made possible by an exact bias current control method. Monte Carlo simulations and extensive PVT analysis verify the circuit's robustness. Power-sensitive applications benefit greatly from the CSVCO's broad tuning range (0.119–2.91 GHz), low power consumption (1.16 mW), and phase noise of -91.80 dBc/Hz at a 1 MHz offset. In order to improve tuning and spectrum purity, the second design is an LC-VCO with a current-controlled tail biasing structure. The LC tank balances low noise, efficiency, and stability for UHF wireless systems by improving phase noise, attaining -128.37 dBc/Hz at 1 MHz offset throughout a tuning range of 2.418–2.439 GHz with a 5.66 mW power consumption. These ideas improve the efficiency and dependability of contemporary UHF circuits by introducing innovative tuning methods and optimizations. © 2025 National Institute of Science Communication and Policy Research. All rights reserved.