Design and analysis of PVT tolerant hybrid current starved ring VCO with bulk driven keeper technique at 45 nm CMOS technology for the PLL application

Abstract

This article introduces a novel approach of hybrid current-starved ring voltage-controlled oscillator (VCO) to overcome the challenges present in the Phase-locked loop (PLL) in high-frequency applications. In this, two novel VCO designs are proposed. The first design is the current starved pull-up sleepy ring VCO which offers improved frequency of oscillation and reduced phase noise. The second design utilizes a hybrid current starved ring VCO with the bulk-driven keeper technique which yields better results by reducing the power consumption and mitigating leakage current. The proposed circuit is analysed with various process corners and performs parametric analysis and Monte-Carlo analysis to verify the robustness of the circuit using Cadence Virtuoso tool with 45 nm gpdk library. The average power of the proposed −2 circuit is 7.38 µW, and it achieves an oscillation frequency of 6.965 GHz at 1 V supply. It has low phase noise of −121.49dBc/Hz at 1 MHz, and the output noise of −166.42 dB. The obtained figure of merit (FOM) is −185.95dBc/Hz. The proposed design exhibits a frequency tuning range of 92.8 %. The results clearly demonstrate that the proposed design is extremely tolerant to PVT (process, voltage, and temperature) variations making it well suitable for high-frequency PLL applications.