A High-e cient current-mode PWM DC-DC buck converter using dynamic frequency scaling

Abstract

Power Management Integrated Circuits (ICs), such as high-efficient switched mode dc- dc converters are essential building blocks in portable battery operated devices. This work presents design and implementation of a novel high-efficiency current-mode pulse width modulated (PWM) buck converter with dynamic frequency scaling. This circuit is capable of ensuring high efficiency under different load conditions, by dynamically changing the frequency of operation with respect to the load current with the help of a novel frequency decision circuit. In addition, soft start operation protects the circuit from large in-rush current during start up of the converter. The proposed circuit is implemented in TSMC 16nm CMOS technology. Simulation outcome has shown an output voltage of 0.8V, when the input voltage is ranging from 2.3 to 3.6V, with a maximum conversion efficiency of 92.25% (heavy loads) and 92.11% (light loads), making this circuit quite useful in power management ICs.Lower technology nodes such as 16nm dont allow voltage more than 1.8V across their junctions. In this work, 3.3V input supply is converted to 0.8V to supply a digital logic block of memory controller used in micro SD card. The design ensures the difference between no two junction voltages exceed 1.8V.