A GaN-Based Reconfigurable Series-Parallel Hybrid Converter Supporting 48/24/12V Input and 0.8-1.2V Output with 83.7/87.8/90.7% Peak Efficiency

Abstract

This paper presents a Gallium Nitride (GaN) based Point of Load (POL) DC-DC converter with a reconfigurable series-parallel (SP) hybrid topology and a programmable control chip. Depending on the input voltage (VIN) and the output current (IOUT), the converter can be reconfigured to the series capacitor buck topology for improved efficiency. The control chip integrates a digital pulse-width-modulator (PWM), a switched-mode regulation loop, a dead-time (tDEAD) controller, high voltage floating level shifters, and gate drivers. In order to achieve wide range of operation, the switching frqeuency (fSW) and on-time ratio (tONR) can be manually programmed for optimizing zero-voltage-switching (ZVS) at different IOUT. The IC prototype is fabricated in TSMC 0.18 mu m high voltage process. The converter achieves 83.7% peak efficiency and >80% efficiency over 26X load range (0.3 - 8 A) at 48-to-1 V conversion.