High time resolution is key to get the most out of Gallium Nitride (GaN) technology in designing fast and high efficiency power converters. High resolution digital pulse-width modulation (DPWM) can be used, but it needs to be designed with a reasonable operating frequency to avoid high dynamic power dissipation. In this paper, a DPWM based on a programmable delay unit implemented in a closed loop solution is presented. The loop ensures that the elements in the delay chain have the same delay enabling PVT variation rejection and result consistency without the need for a high operating frequency. This allows tuning signals with a resolution of 195 ps and a high linearity, making the unit compatible with the requirements for driving GaN power devices. The system has been implemented in a test chip using 100 V 0.13 μm BCD technology at 40 MHz operating frequency and validated with a custom debug board that confirms the expected resolution over a wide tuning range.

This paper presents a monolithic GaN current sense circuit designed for the high-side of a 100-V half-bridge. The circuit is engineered to minimize current offsets and response times across a wide range of input voltages (10 V to 100 V), as well as varying temperatures and current loads. It is capable of tracking inductor current ripples and detecting the zero-current condition of the half-bridge high-side power transistor. The proposed solution demonstrates a simulated loop gain exceeding 100 dB and a bandwidth of 43.9 MHz, which achieves an accuracy of 99.4% and a response time of 145 ns under operating conditions of 50-V input voltage, 10-A current load, and 27°C.