An SC Voltage Doubler with Pseudo-Continuous Output Regulation Using a Three-Stage Switchable Opamp

• Published in: IEEE journal of solid-state circuits Vol. 42; no. 6; pp. 1216 - 1229
• Main Authors: Hoi Lee, Mok, P.K.T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplifiers; Applied sciences; Capacitors; Charge pumps; Charge transfer; Circuit properties; Circuits; Clocks; CMOS; Control; Design. Technologies. Operation analysis. Testing; Dielectric, amorphous and glass solid devices; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Energy management; Exact sciences and technology; Integrated circuits; Other multijunction devices. Power transistors. Thyristors; power management integrated circuits; Pulse width modulation; Regulators; Ripples; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; switched-capacitor regulators; Switching; Switching circuits; Switching frequency; three-stage switchable amplifier; Transient response; Transient responses; Voltage control; Voltage doublers; voltage regulators; Performance evaluation; Feedback regulation; three-stage switchable amplifier; Time division multiplexing; Implementation; Power transistor; switched-capacitor regulators; Predictor corrector method; Active system; Complementary MOS technology; Output voltage; Power losses; Charge pumping; Multistage circuit; Transient response; Charge pumps; Operational amplifier; Frequency doubler; voltage doublers; Voltage regulation; power management integrated circuits; Recovery time; Switching; voltage regulators; Power integrated circuits; Capacitor; Voltage multipliers
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2007.897133

This paper presents a switched-capacitor voltage doubler using pseudo-continuous control (PCC). The proposed PCC does not require extra power transistor to continuously regulate the output of the doubler, thereby saving chip area. The PCC also allows the doubler to operate at lower switching frequencies without sacrificing transient response. The light-load efficiency of the regulated doubler can thus be enhanced by reducing the switching power loss. In addition, a three-stage switchable opamp with time-multiplexed enhanced active-feedback frequency compensation is developed to implement the controller. The proposed implementation enhances the speed of the loop response and then improves the load transient response of the regulated doubler. The SC voltage doubler with the proposed PCC controller has been fabricated in a 0.6-mum CMOS process. The regulated doubler achieves >87% power efficiency even for the load current of 5 mA. By operating the doubler at switching frequency of 200 kHz and using a output capacitor of 2.2 muF, a maximum output ripple of 20mV is maintained for the load current changing from 50 mA to 150 mA. The output transient recovery time of the regulated doubler is ~25 mus with load-current step changes of 100 mA/1 mus