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 45 V 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 muW, and the proposed buck converter operates at a peak efficiency of 82 %. The input voltage range of the regulator is from 1:5 V to 45 V and has a power range from 10 muW to 200 mW. The output regulated voltage is tunable via a feedback resistor and can be varied from 0:6 V to 40 V, with a dropout voltage of 1V.