PT controlled PCCM buck converter with adaptive pulse train generator and NMOS current sensor

Abstract

A pulse train controlled buck converter operating in pseudo continuous conduction mode (PCCM) is implemented in the 0.18-μm CMOS process in this paper. An adaptive pulse train generator, which adjusts duty cycle based on the output power, is proposed to improve the output voltage range and transient response. To operate in PCCM, an NMOS current sensor using a double common-gate amplifier with a high slew rate is utilized to detect the falling inductor current. Simulation results demonstrate that the converter obtains a well regulated variable output voltage from 1 V to 4 V, providing a maximum load current of 1000 mA at the switching frequency of 1 MHz. The transient spike is smaller than 35 mV and recovery time is less than 6.3μs for a 300 mA load current step. The peak efficiency is 94.4% at 300-mA load current.