A 10-MHz Current-mode Constant On-time Boost Converter with a Translinear Loop-based Current Sensor

Abstract

DC-DC converters with a high switching frequency are very attractive when fast-response, and small-area are required. In this paper, a translinear loop (TLL)-based digitally controlled current sensor is proposed for boost converters with the switching frequency of 10 MHz. Compared to previous current sensors, the proposed circuit helps to minimize the sensing response time by removing a slow feedback loop. It also uses a digital control to get an accurate sensing waveform. In addition, a ripple-based constant on-time (COT) control helps to further reduce the load-transient response. The proposed boost converter has been fabricated in a 180-nm CMOS process with a total chip area of 1.28 mm × 1.18 mm. The maximum conversion efficiency of 93.3% has been achieved even at the 10-MHz switching frequency, and 3.5-μs transient response time is measured at 400 mA of a load current step.