Integrated hysteretic controlled regulating buck converter with capacitively coupled bootstrapping

Abstract

This paper presents the circuit design, layout implementation and simulations of an on-chip hysteretic regulating buck converter. All the high voltage transistors of the buck converter were implemented using 45V NMOS thin gate oxide layer transistors and are operated by means of a capacitively coupled bootstrap circuit. The circuit was implemented using the XFAB CMOS 0.35 μm high voltage technology and all the circuit blocks were designed using analog electronic techniques, with the transistors operating in the sub-threshold region, in order to minimize power consumption. Simulations show that the control circuit of the hysteretic regulator consumes around 0.5 μW, and the proposed buck converter operates at a peak efficiency of 82%. The input voltage range of the regulator is from 1.5V to 45V and has a power range from 10 μW to 200mW. The output regulated voltage is tunable via a feedback resistor and can be varied from 0.6V to 40V, with a dropout voltage of 1V.