THESIS
2002
x, 71 leaves : ill. ; 30 cm
Abstract
Switched-capacitor power converters, or charge pumps are built from a series of switches and capacitors. Without bulky inductors, the electromagnetic interference problem is reduced and they can be fabricated completely on an integrated circuit for low power applications. Various types of charge pumps have been developed including step-up charge pumps, step-down charge pumps, inverting charge pumps and bi-directional charge pumps....[
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Switched-capacitor power converters, or charge pumps are built from a series of switches and capacitors. Without bulky inductors, the electromagnetic interference problem is reduced and they can be fabricated completely on an integrated circuit for low power applications. Various types of charge pumps have been developed including step-up charge pumps, step-down charge pumps, inverting charge pumps and bi-directional charge pumps.
This research presents a novel bi-directional charge pump that can be used in a battery charging and discharging system. For step-up conversion, the circuit is a 3X charge pump with an input voltage of 1.8V at the low voltage port (LV). The output at the high voltage port (HV) is regulated to 4.5V. For step-down conversion, the circuit becomes a 1/2X charge pump with an input voltage of 4.5V at HV. The output at LV is regulated back to 1.8V. Each port voltage can be regulated using the switching low dropout regulator technique when it serves as the output. The converter was designed and fabricated using an AMS 0.6μm CMOS n-well process. The switching frequency is 250kHz. Measurement results show that each output delivers a load current of 20mA with good line and load regulation. The efficiencies are 72% for the step-up case and 73% for the step-down case.
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