An Adaptive Daul Step Control Dead-Time Circuit for Gallium Nitride Half-Bridge

Abstract

In order to reasonably design the dead time and reduce the ineffective energy consumptions of the circuit in the dead time, an adaptive dual-step control dead time circuit suitable for GaN(gallium nitride) half-bridge structure is proposed. The circuit mainly detects the when the voltage of the switch node drops to the bias voltage by detecting the falling edge, skips the time that causes the shoot-through loss by designing the corresponding time delay, and then detects the negative voltage of the switch node and outputs an effective output Logic level, carry out digital feedback to the capacitor array unit, effectively control the capacitor array to perform dynamic dead time delay, use digital control to continuously adjust the dead time, so that the dead time can achieve the optimal result, reducing the system power consumption in dead time, improving system performance. This circuit is based on a standard 0.35μm BCD (Bipolar-CMOSDMOS) process and 40V LD-MOS(Laterally Diffused Metal-Oxide Semiconductor)high voltage devices, and the dead zone control circuit is verified at a frequency of 1 Mhz. The results show that when the input voltage is 40V and the load current is 26.67mA, the negative voltage feedback judgment output is input to the reversible counter continuously switches between 0010 and 0011 for dynamic time delay, so that the dead time is near the ideal time, the dynamic delay time of 0010 is 5.87ns, and the state delay of 0011 the time is 7.10ns, and the dynamic adjustment step is about 1.23ns, compared with the traditional fixed dead time, the efficiency is improved by about 3%.