A New Approach to Increase the Operating Frequency and the Duty-Cycle Range of High-Speed Level Shifter in 600V Gate Driver

Abstract

High speed and high voltage level shifter using cross-coupled circuits in GaN FET driver, has potential capability to achieve exceeding 200V/ns slew immunities and sub-ns propagation delay. However, it can be found that output of the level shifter is incorrect when the input signal pulse width is smaller than the trigger pulse width. It means that although it has smaller propagation delay, the level shifter cannot work correctly in wild range of input signal duty cycle. This paper presents a novel approach to achieve wilder range of duty cycle. Based on 0.8μm 600V BCD process, simulation results of the proposed circuit show that minimum width of signal pulse is less than 1ns with the floating ground from zero to 600V. The duty-cycle range can be extended from 60% to 96% when signal frequency is 20MHz and triggered pulse width is 10ns. At the same time, the level shifter’s propagation delay is 5.9ns, power rail slew immunities over 200V/ns and power consumption of the proposed level shifter almost equals to that of traditional circuit.