遠距離無線充電系統之射頻功率放大器與射頻整流器

Abstract

本論文主旨是完成遠距離無線充電系統，完成功率放大器透過天線經能量傳到整流器中最後向功率損耗低的裝置進行充電。 本論文主要分為三個部分，第一部分為設計射頻功率放大器，採用增強模式高電子移動率製成的電晶體(E-pHEMT)製作，在印刷電路板(Printed Circuit Board,PCB)上透過SMD元件做匹配，單級的功率放大器量測結果，當輸入功率17 dBm時，最佳功率附加效率為53.5%，輸出功率為26.15 dBm。藉由威爾金森功率分配器(Wilkinson Power Divider)接上四個相同架構的射頻功率放大器，做成兩級功率放大器。量測結果為在3.6 V供應電壓以及單頻(CW)在2.4 GHz時，當輸入功率為13 dBm時，整體最佳功率附加效率為49%，此時的整體輸出功率約為31.5 dBm。 第二部分是設計射頻整流器，採用90奈米 CMOS製成實現，面積約為0.65×0.45 〖'mm' 〗^'2' 。根據量測結果，在2.4 GHz下，輸入功率為-6 dBm以及0 dBm時，最佳能量轉換效率分別有31.9%以及42.6%，其直流電壓約有1.15 V以及1.62 V。 第三部分則是將前兩部分的功率放大器以及整流器全部整合再一起並實現遠距離無線充電，發射端使用的是4×1的陣列天線，增益值為10 dBi，面積為7×28 cm^2，接收端使用的是1×1的陣列天線，增益值5 dBi，面積為7×7 cm^2。當距離在0.3公尺至3公尺時，經由弗里斯傳輸方程推算，該操作頻率下的空氣損耗，公式算出來的與量測出來的是接近的。當發射端的輸出功率為30.5 dBm時，1.2公尺時的接收功率為0.6 dBm，此時整流出來的電壓為1.62 V，能量轉換效率為35.4%；3公尺時的接收功率為-6.6 dBm，此時整流出來的電壓為1.15 V，能量轉換效率為26.5%。

The main purpose of the dissertation is to complete the Far-Field wireless power charging system. The Radio-Frequency power amplifier amplifies the signal and transmits to the rectifier by antennas. Finally, the received Radio-Frequency power will be rectified from RF signal into DC signal and charge the low power consumption devices. This thesis is divided into three parts. The first part is to design a power amplifier using the enhanced-pseudomorphic-high-electron-mobility-transistor with the SMD components on the PCB. The measurement results of the peak power added efficiency is 53.5 % and output power is 26.15 dBm under a supply voltage 3.6 V at 2.4 GHz. Four identical power amplifiers combined by a wilkison power divider forms a two stage power amplifier. The measurement results of the peak total power added efficiency is 49 % and the total output power is 31.5 dBm under a supply voltage 3.6 V at 2.4 GHz. The second part is to design a rectifier in 90 nm CMOS technology The chip area is 0.65×0.45 〖'mm' 〗^'2' . According to the measurement results, the power conversion efficiencies are 31.9 % and 43 % and the output voltages are 1.15 V and1.62 V with the input power under -6 dBm and 0 dBm, respectively, at 2.4 GHz. The third part reports the Far-field wireless power charging systems. The gain of the 4×1 transmitting antenna is 10 dBi and the size is 7×28 cm^2.The gain of the 1×1 receiving antenna is 5 dBi and the size is 7×7 cm^2. The free space loss is calculated with the Friis transmission equation at operating frequency and distance. The measured results are close to the theoretical values at the distance from 0.3 m to 3 m. When the output power of the transmitter is 30.5 dBm, the received power at 1.2 meters is 0.6 dBm, the rectified output voltage is 1.62 V, and the power conversion efficiency is 35.4%. The received power at 3 meters is -6.6 dBm, the rectified output voltage is 1.15 V, and the power conversion efficiency is 26.5%.