A Monolithic Current-Mode CMOS DC–DC Converter With On-Chip Current-Sensing Technique

TLDR

The paper presents a monolithic current‑mode CMOS DC‑DC converter that integrates power switches and a novel on‑chip current sensor for feedback control. The converter employs an accurate on‑chip current sensor that measures the inductor current and, together with an internal ramp signal, provides feedback control without external components or extra I/O pins, and is fabricated in a standard 0.6‑µm CMOS process. Experimental results show less than 4 % absolute error between sensed and actual inductor current, operation from 300 kHz to 1 MHz with 3–5.2 V supply, 20 mV output ripple, and over 80 % efficiency for 50–450 mA load, making it suitable for single‑cell lithium‑ion battery supply applications.

Abstract

A monolithic current-mode CMOS DC-DC converter with integrated power switches and a novel on-chip current sensor for feedback control is presented in this paper. With the proposed accurate on-chip current sensor, the sensed inductor current, combined with the internal ramp signal, can be used for current-mode DC-DC converter feedback control. In addition, no external components and no extra I/O pins are needed for the current-mode controller. The DC-DC converter has been fabricated with a standard 0.6-/spl mu/m CMOS process. The measured absolute error between the sensed signal and the inductor current is less than 4%. Experimental results show that this converter with on-chip current sensor can operate from 300 kHz to 1 MHz with supply voltage from 3 to 5.2 V, which is suitable for single-cell lithium-ion battery supply applications. The output ripple voltage is about 20 mV with a 10-/spl mu/F off-chip capacitor and 4.7-/spl mu/H off-chip inductor. The power efficiency is over 80% for load current from 50 to 450 mA.