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 V_OUT 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.