A novel on-chip soft-started DC-DC buck converter for biomedical applications

An integrated pulse width modulation (PWM) step-down CMOS DC-DC converter with integrated power switches and a novel on-chip soft-start circuit is presented in this paper. This converter consists of internal ramp signal generator, comparator, error amplifier, PWM control scheme, and a soft-start scheme. The soft-start circuit can produce a slowly rising output voltage without extra clock or any external component to prevent inrush current and output voltage overshoot during the start-up period of the DC-DC converter. Compared with conventional designs, the advantages of proposed DC-DC converter are simple structure, portability, stability and high efficiency, which are very important features for the portable biomedical applications. Back-annotated results showed that the DC-DC converter operates at 1MHZ with supply voltage from 4.8V to 5.5V and a peak efficiency of 91%. The results proved that the proposed buck DC-DC converter is suitable especially for portable biomedical devices that require stability and high efficiency.