Design of a Ring-Type SC DC-DC Converter withBootstrapped Gate Transfer Switches

In this paper, a ring-type SC DC-DC converter with novel bootstrapped gate transfer switches is proposed. The bootstrapped gate transfer switches are used to achieve higher efficiency. In the proposed bootstrap circuit, maximum voltage of the power converter is charged to a capacitor via maximum circuits constructed with diodes. By connecting the charged-capacitor between the gate terminals of power-switches and the output terminal of the maximum circuit, the bootstrap circuit avoids the threshold voltage drop of power-switches. Concerning the DC-DC converter designed by a 1.2 μm CMOS technology, SPICE simulations are performed to investigate the characteristics of the circuit. The SPICE simulations show that the efficiency of the DC-DC converter with proposed bootstrap circuits is more than 90 % when the output load R_o satisfies R_o > 200 Ω. When R_o = 100 Ω, the proposed circuit can improve efficiency up to 8.7 % of a conventional converter. The validity of the circuit design for the bootstrap circuit is also confirmed by experiments.