使用電感耦合寬頻天線之射頻辨識標籤中AC/DC

Abstract

無線射頻標籤在UHF頻帶長距離應用中，將射頻能量轉直流的功率轉換效率極為重要。本論文研究與寬頻天線（915MHZ）結合的被動標籤前端，其中設計高轉換效率的電荷泵及與天線輸入阻抗的匹配更是焦點所在。 利用金氧半製程實現射頻辨識標籤中的AC/DC電荷泵電路，此AC/DC電荷泵電路設計採用TSMC 0.18um製程，其倍壓率為8.575倍、溫度變化範圍0~80度、操作頻率為915MHz~2.4GHz之間、DC輸出穩壓位準為850mV、上升時間為1.3776ms、下降時間為8.6546ms、射頻能量感應範圍-6dBm~6dBm；利用電感耦合理論實現寬頻天線，利用0.4mm FR4板去實現寬頻天線，其頻寬為626MHz、在共振頻率915MH時增益為2.701dbi。在電荷泵電路與電感耦合寬頻天線輸入阻抗為共軛匹配時，且直流輸出電壓為1.3V，其量測距離可以到達4.3m。

Radio frequency identification (RFID) has received much attention.The RF to DC conversion efficiency is crucial for long range application in UHF band.The front end of the passive tag combined with the broadband antenna at 915MHz is investigated. Two subjects of high efficient charge-pump and antenna matching are focused in this study. This AC/DC charge-pump circuit is manufactured by TSMC 0.18um process.The multiplier factor is 8.575 for ten stage conversion.It can perform well at 0~80℃ and at 915MHz~2.4GHz.The dc voltage is regulated to 850mV with input power lying between -6~6dBm.Its Rising Time and Falling Time are 1.3776ms and 8.6546ms, respectively.Based on the Inductively-coupled mechanism, its bandwidth achieves 626MHz.The antenna gain is 2.701 dbi centered at 915MHz.Under complex conjugate matching between antenna and charge pump, the measured range can reach 4.3m with stable DC output voltage equal to 1.3V.