A 0.791 mm On-Chip Self-Aligned Comparator Controller for Boost DC-DC Converter Using Switching Noise Robust Charge-Pump Tae-Hwang Kong, Student Member , IEEE , Sung-Wan Hong , Student Member , IEEE ,a n d

Abstract

Herein we propose a new PWM controller for a DC-DC converter with a Self-aligned Comparator Control (SCC), the purpose of which is to overcome sub-harmonic switching and hysteretic characteristics that are problematic in conven- tional comparator control sch emes. In the proposed scheme, the condition of the output voltage is converted to the form of a phase difference through the SCC block. The main control loop of the converter regulates the inductor current w hich is built up to an optimum value by using this phase difference. In addition to the SCC, the proposed PWM controller is fully integrated on-chip without off-chip components to decrease the size and cost of the DC-DC converter using a new Switching Noise Robust Charge-pump (SNRC). A boost DC-DC converter with the proposed SCC and SNRC was designed and fabrica ted in a commercial 0.35 m BCDMOS process with total controller area of 0.791 mm 2. A maximum ef ficiency of 90% was achieved at a total output power of 480 mW with a switc hing frequency of 926 kHz when the input and the output voltages were 3.7 V and 8 V , respectively. Over 85% efficiency was maintained over a wide range of output load current from 40 mA to 3 00 mA.