A 0.9-V Input Discontinuous-Conduction-Mode Boost Converter With CMOS-Control Rectifier

• Published in: IEEE journal of solid-state circuits 2008-09, Vol.43 (9), p.2036-2046
• Main Authors: Man, T.Y., Mok, P., Chan, M.J.
• Format: Article
• Language: English
• Subjects: adaptive dead-time; Applied sciences; boost converter; Capacitors; Circuit properties; CMOS process; Design. Technologies. Operation analysis. Testing; discontinuous-conduction mode; Efficiency; Electric power; Electric, optical and optoelectronic circuits; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Inductors; Integrated circuits; Process design; Pulse modulation; Rectifiers; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Signal convertors; Space vector pulse width modulation; Sub-1V; Switches; Switching frequency; Switching, multiplexing, switched capacity circuits; Thermal stresses
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2008.2001933

A 0.9-V input discontinuous-conduction-mode (DCM) boost converter delivering 2.5-V and 100-mA output is presented. A novel low-voltage pulse-width modulator is proposed. The modulator can be directly powered from the 0.9-V input instead of using the 2.5-V output as in general modulator designs. Sophisticated low-voltage analog blocks, which normally consume a large amount of power and chip area, are not required in the modulator. The impact of output-voltage ripple and transient-induced output-voltage perturbation on the operation of analog blocks inside the modulator is eliminated. Boost converter start-up sequence is also greatly simplified. A CMOS-control rectifier (CCR) is also proposed to improve converter power efficiency. The CCR is used to replace the conventional rectifying switch to provide adaptive dead-time, which helps to minimize charge-sharing loss and body-diode conduction loss. Corresponding thermal stress on the rectifying switch is hence minimized. The CCR also enables the use of small off-chip inductor and capacitor at sub-MHz switching frequency to improve light-load efficiency. This converter has been implemented in a 0.35- mum CMOS process. It is designed to operate at ~ 667 kHz with a 1 mu H inductor and 4.7 mu F output capacitor to reduce both switching loss and form factor. Experimental results prove that the converter can be directly powered from 0.9-V input with ~ 85% efficiency at 100-mA output.