Design Of A Charge Pump Switching Power Chip

Power supply is necessary for modern electronic devices and equipment. In this thesis, a charge-pump switching power-supply chip is designed based on CMOS technology and using HSPICE simulation tool to satisfy requirements of compact electronic instruments with high performances and small weight. The research work includes the chip circuit operating elements, circuit system design and simulation.The chip can be operated to output a constant 5-V voltage in an input voltage range of 2.7 V to 5.5 V. Bandgap-reference and hysteresis-comparator modules are key modules of this chip since temperature characteristics and output-voltage ripples of the whole chip depend on the two modules, and at the same time, their static power will seriously affect conversion efficiency of the chip. A bandgap reference circuit with new curvature-compensated technology which provides a low temperatue coefficient(TC) of 4.5 ppm/℃and a high power supply rejection ratio(PSRR) of 57 dB is employed. The bandgap circuit has a low power supply current of 13μA. For the design of hysteresys comparator, the high-speed operational amplifier is used to improve system feedback velocity and reduce output voltage ripple.The chip can be operated with three modes: shutdown mode, sleep mode and work mode. When the charge pump is applied with sleep mode 30μA current from power is only drawn to improve converter efficiency under low load condition. Simulation results show that high performance is arrived in the chip, such as: converter efficiency(83%), TC (4.5 ppm/℃) and output voltage ripple(30 mV). The design requirement is fully arrived.