A Novel Voltage-Controlled Oscillator Linearized by a Resistorless Dynamic-Degeneration Technique

We present a novel, highly-linear, and area-efficient voltage-controlled oscillator (VCO) design based on a ring oscillator (RO) structure, suitable for high-speed VCO-based analog-to-digital converters. This proposed VCO employs a degenerated transconductor embodying a proposed resistorless dynamic-degeneration linearization technique (RDD). In contrast to conventional degeneration methods, the RDD utilizes transistors as a degeneration resistor, thereby eliminating the need for a large resistor. The RDD dynamically regulates the degeneration resistance through a feedback loop, consequently resulting in a linear voltage-to-frequency response of the VCO. We design the proposed VCO in a 65 nm CMOS technology and conduct simulations to benchmark it against state-of-the-art ROs. Based on this benchmarking, the proposed VCO features the smallest IC area of $\mathbf{1 2 0} \boldsymbol{\mu m}^{2}$. Furthermore, it achieves an exceptionally competitive maximum non-linearity error of $\mathbf{0. 5 \%}$ under typical conditions and an average of $\sim 1.4 \%$ under global process variations (Monte Carlo), across the widest frequency range from 460 MHz to 1.77 GHz.