Cascoded GaN half-bridge with 17 MHz wide-band galvanically isolated current sensor

Abstract

A cascoded GaN half-bridge with wide-band galvanically isolated current sensor is proposed. A 650-V depletion-mode GaN FET is switched by a low-propagation-delay gate driver in active-mode. The standby and active modes are switched by a 25-V N-ch LDMOS. The current sensor uses the LDMOS as a shunt resistor, gm-cell-based sense amplifier and mixer based isolation amplifier for wider bandwidth. PVT variations of on-resistance of the current-detecting MOSFET are compensated using a reference MOSFET. A digital calibration loop across the isolation is formed to keep the current sensor gain constant within ±1.5% across the whole temperature range. The wide-band current sensor can measure power device switching current. In this study, a cascoded GaN half-bridge switching and inductor current sensing using low-side and high-side device current are demonstrated. The proposed techniques show the possibility of implementing a GaN half-bridge module with isolated current sensor in a package.

GaN Transistors’ Radiated Switching Noise Source Evidenced by Hall Sensor Experiments Toward Integration

“…This is why, current extensive research focuses on studying active monitoring and control methods for the GaN transistors [24][25], via simulation [26] [27] and equivalent circuit experiments since integrated circuits (ICs) based on GaN technology involves a more difficult process [28][29] as compared with its predecessor Silicon chips [30] or to the more exotic technology like diamond based semiconductors [31] [32]. Additionally, since the power designs based on GaN transistor technologies are very sensitive to external monitoring circuits that may limit the design performance [33], galvanically isolated sensors [34] [35] with magnetic coupling [36][37] [38] are the next promising solution.…”

Fully Integrated Galvanic Isolation Interface in GaN Technology

“…Moreover, to enhance performance of GaN power switches a fully integrated circuit (IC) approach has been attempted through the implementation on the same substrate of low-power and high-power GaN transistors, thus overcoming the performance limitations due to parasitic inductances between driver and power switch [5], [6], [7]. This solution minimizes losses and allows higher switching speed, efficiency, and compactness to be achieved.…”