A 40-MHz current-mode hysteretic controlled switching converter with digital push-pull current pumping technique for high performance microprocessors

Ever-increasing power demands of microprocessors have necessitated fast-response, high-speed power converters. This paper presents a fast transient, hysteretic current-mode converter design with a push-pull current pump. By using a current feedback technique in contrast with the parallel feedback control approaches by the prior art, performance and stability are greatly enhanced. The system is implemented and verified on a 0.18 μm CMOS process through fully transistor-level simulations, operating up to 40 MHz. In comparison with the buck converter by itself, the current pump improves the transient response by reducing VOUT undershoot magnitude and settling time by 33.3% and 25.6%, respectively, and overshoot magnitude and settling time by 18.3% and 40.4%, respectively. Undershoot and overshoot are maintained below 3%, at 2.8% and 2.9%, respectively.