A common-gate bootstrapped CMOS rectifier for VHF isolated DC–DC converter

Abstract

A common-gate bootstrapped CMOS rectifier dedicated for VHF (very high frequency) isolated DC–DC converter is proposed. It uses common-gate bootstrapped technique to compensate the power loss due to the threshold voltage, and to solve the reflux problem in the conventional rectifier circuit. As a result, it improves the power conversion efficiency (PCE) and voltage conversion ratio (VCR). The design saves almost 90% of the area compared to a previously reported double capacitor structure. In addition, we compare the previous rectifier with the proposed common-gate bootstrapped rectifier in the case of the same area; simulation results show that the PCE and VCR of the proposed structure are superior to other structures. The proposed common-gate bootstrapped rectifier was fabricated by using CSMC 0.5 μm BCD process. The measured maximum PCE is 86% and VCR achieves 77% at the operating frequency of 20 MHz. The average PCE is about 79% and average VCR achieves 71% in the frequency range of 30–70 MHz. Measured PCE and VCR have been improved compared to previous results.