A 40nm CMOS Hysteretic Buck DC-DC Converter With Digital-Controlled Power-Driving-Tracked-Duration Current Pump

A fast-transient voltage-mode hysteretic buck converter with digital-controlled power-driving-tracked-duration (PDTD) auxiliary current pump is proposed. The pump injection current duration is digitally controlled by the driving signal of the power stage. It aims at enhancing the transient response time which is limited by the large inductor used in typical buck converters and reducing the multiple undershoot/overshoot effect encountered in conventional current pump injection technique. The converter has been fabricated using TSMC 40nm CMOS technology with the silicon area of 830\mu \text{m}\times 620\mu \text{m} . The proposed converter regulates properly in both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). The measured output ripple is about 30mVpk and the switching frequency is about 1.45MHz. The peak efficiency is 93%. The measured load transient settling time for a 60-to-300mA/300-to-60mA load step change is 369ns/335ns, resulting in 350% faster than that of conventional counterpart without PDTD control scheme. The performance comparison with the representative state-of-art works has shown that the proposed converter shows good balance on performance metrics and the best figure-of-merit (FOM) in transient-response efficiency.