A GaN Driver for a Bi-Directional Buck/Boost Converter With Three-Level VGS Protection and Optimal-Point Tracking Dead-Time Control

This paper presents a gate driver for a GaN-based half-bridge structure operating in a buck converter with input voltage >40 V or a boost converter with output voltage >30 V. Two 500 pF on-chip capacitors are utilized to construct three-level gate drivers, providing a near-
$V_{{\text {DD}}}$
negative voltage for gate of the rectifier switch to eliminate the induced pulse on the gate from the high
dv
/
dt
slew rate of
$V_{\text {X}}$
when the main switch is turned on. The dead time controller tunes the delay of the gate signal of the rectifier switch by sensing the slope of
$V_{\text {X}}$
, thus the near-optimal zero-voltage switching can be achieved with deviation < 3 ns. The GaN driver is implemented with a 0.18-
$\mu \text{m}$
BCD process. The efficiencies can be improved by 8.33% and 6.87% at light load in a buck and a boost converter due to the dead-time control. The peak efficiencies of 20 V–12 V and 12 V–18 V conversions are 86.37% and 84.39%, respectively.