A monolithic current-mode CMOS DC-DC converter with on-chip current-sensing technique

• Published in: IEEE journal of solid-state circuits Vol. 39; no. 1; pp. 3 - 14
• Main Authors: Cheung Fai Lee, Mok, P.K.T.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2004; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Battery charge measurement; Capacitors; CMOS; CMOS process; Converters; Current measurement; DC-DC power converters; Electric potential; Feedback control; Inductors; Pins; Ripples; Sensors; Switching converters; Voltage
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2003.820870

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.