A 100-MHz Multi-Step Pulse-Width Modulator for Low-Power Signal Isolation in Gate Drivers for Wide-Bandgap Devices

Abstract

High-performance and high-reliability gate drivers are essential for fully exploiting the switching capability of wide-bandgap (WBG) power devices. Due to the large voltage differences inherent to high-voltage power stages, robust signal isolation is required to reliably transfer control commands across domains. Inductive or capacitive coupling techniques are typically employed to achieve low-latency isolation, among which inductive coupling offers improved immunity to common-mode transient noise compared with capacitive counterparts. However, when the transmitted pulse width becomes excessively long, conventional inductive-coupling isolators suffer from substantial static current consumption, leading to increased power dissipation and thermal stress. To address these challenges, this work introduces a multi-step pulse-width modulator optimized for low-power isolators. Implemented in a 0.18-µm CMOS process, the proposed scheme conveys data through a short sequence of narrow, adjustable pulses rather than continuous current flow, enabling event-driven operation that substantially reduces average DC current. Post-layout simulations using a highly realistic transformer model with a 105 nH primary inductance and parasitic elements show that the isolator current can be tuned from 5.563 mA to 11.48 mA, significantly lower than the 20.86 mA required by the conventional approach. By lowering power consumption while preserving robust signal transfer, the proposed method supports higher system integration and improved long-term reliability.