| Summary: | 碩士 === 國立臺灣大學 === 電子工程學研究所 === 97 === In recent years, harmonic distortion problem has been emphasized. To achieve the standards which were made by each country, power factor correctors have played an important role in switching power supplies. In current architecture of active power factor corrector, input current is controlled by input voltage which multiplies feedback control signal to become sinusoidal wave; hence analog multipliers are the heart of the control circuits. This thesis mainly discusses on an analog multiplier which can be applied to power factor corrector, and purposes a method by shifting input voltage up one threshold voltage, improving the analog multiplier using linear variable resistor applies in non-inverting amplifier. The linear variable resistor is composed of two MOS in parallel. One is operated in linear region, and the other is operated in saturation region. The value of linear variable resistance will change by input; therefore change the gain of non-inverting amplifier to realize multiplier. In this thesis, a complete boundary conduction mode boost PFC circuit is built with the proposed multiplier. Finally, simulation outcomes of Hspice verify that the purposed multiplier can be used for PFC circuit.
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