In the thesis, an LED driver circuit that is applied in low power lighting LED with constant output current and Power Factor Correction (PFC) is presented. The insulated Flyback converter is used for the LED driver. Power Factor Correction is realized with both the method of Voltage Follower Approach Control under Discontinuous Conduction Mode and the method of Boundary Conduction Control under Boundary Conduction Mode. Compared with Voltage Follower Approach Control, Boundary Conduction Control needs only output current feedback. Moreover, it possesses lesser magnetize inductance current, lesser electrical stress of elements, more flexible choice of elements specification, smaller output current ripples, and higher power factor under light load. The circuit design is expounded, and verified by IsSpice simulation and experiment result.

The proposed circuit intends to harvest kinetic energy from ElectroMagnetic Generators (EMGs). In order to extract maximum power from an EMG, an AC-DC boost rectifier is designed to match the impedance of the EMG. Rather than operate a buck-boost converter in Discontinuous Conduction Mode (DCM) in other impedance matching cases, the proposed method is running the boost topology in Boundary Conduction Mode (BCM). So it would perform resistive input matching, while reducing the converter power loss. The boost rectifier also merges a rectifier and a boost converter to reduce power loss for rectification. It also utilizes the internal inductance of the EMG to eliminate the impedance matching error and reduce the off-chip inductor size. An optional buck converter regulates the output voltage to 5 V to power devices through USB ports. The proposed circuit is designed and fabricated in BiCMOS 0.18 μm technology. Its functionality is shown through simulation results. The measurement of the IC is also performed. However, since the IC only work partially, test result is gathered using some discrete components as substitutes. It indicates the circuit can realize the proposed control method. / Master of Science / The development of energy-efficient semiconductor devices has reduced the power requirements of electronic circuits. As the electronics’ scale decreases, so does the energy consumption. In this sense, batteries were also produced in smaller size providing more energy storage availability. However, due to technical and technological issues, the batteries have not been followed by the same evolutionary trend limiting the operational time and performance of portable devices as it need to be recharged or replaced periodically. On the other hand, portable electronic devices such as cell phones, GPS, cameras, etc. are powered only by batteries. For circumstances that power supplies are not accessible, energy harvesting (EH) from human or environmental sources has proven to be an effective alternative or complement. Light, thermal, mechanical and RF are major sources in EH. Among them, mechanical energy from wind, waves, vibrations, etc. is commonly existed in our daily life. The energy is harvested by using micro generators and the various types include electromagnetic, piezoelectric and electrostatic. In particular, the ElectroMagnetic Generator (EMG) is of great interest for its potentially high energy density and efficiency. Since EMG is an AC voltage generator while portable devices usually require a stable DC supply, an EH circuit as a rectifier ought to be designed. At the same time, for EH application, we would like to harvest as much power as possible from EMGs. This research project addresses the development of a unique EH circuit capable of fulfilling the distinct needs illustrated above.