Design and implementation of a 0.8 V input, 84% duty cycle, variable frequency step-up converter

A 0.8 V input, 84% duty cycle, variable frequency CMOS DC–DC step-up converter with integrated power switches has been presented in this paper. The converter has the properties of both the current mode and hysteric control mode operations. The inductor charging time of the topology is designed to be inversely proportional to the input voltage and as a result the inductor current disturbance dies out immediately. Hence, no external components and extra I/O pins are required for the compensation of the current loop. The step-up converter has been fabricated with a standard 0.5μm pseudo BiCMOS process. Special MOS device of threshold voltage 0.5 V and start-up circuitries enable the converter to start from a voltage as low as 0.8 V. The real time data show that the converter can boost 0.8 V to as high as 5 V, which makes it suitable for low voltage applications. The efficiency of the chip has been found over 75 % for the entire load range from 10 to 100 mA.