Amplitude-to-Phase Conversion in Injection-Locked CMOS Ring Oscillators

TL;DR

This paper presents an advanced analytical model for injection-locked CMOS ring oscillators that explicitly accounts for amplitude-to-phase conversion, improving understanding and prediction of their locking behavior.

Contribution

It extends Adler's equation to include amplitude-to-phase conversion effects in ILROs, providing a more accurate analytical framework.

Findings

Model accurately predicts locking range

Simulation aligns with analytical predictions

Enhanced understanding of amplitude-to-phase effects

Abstract

Injection-locked ring oscillators (ILROs) are extensively employed for multi-phase clock generation in wireline and optical links. However, existing injection-locking theorems primarily rely on linearized phase-domain or nonlinear time-domain models, which fail to account for amplitude-to-phase conversion effects inherent in ILROs. This paper introduces an enhanced analytical model based on an extension of Adler's equation, explicitly incorporating amplitude-to-phase conversion. Simulation results demonstrate strong alignment with the proposed analytical predictions, validating the model's accuracy in capturing the locking range and phasor relationships.