使用密封環天線之60 GHz(下行) / 24 GHz(上行)被動式RFID電子標籤

Abstract

無線射頻辨識系統(RFID)近年來被廣泛的使用於日常生活中，如門禁系統、捷運悠遊卡、電子收費系統等等。RFID需要天線來感應及產生無線電波，而傳統的RFID電子標籤使用外接的天線，並且操作在低頻，天線的大面積及成本使得RFID的應用受限。 為了解決傳統RFID電子標籤的大面積及成本問題，本論文首次提出了晶片面積為1毫米平方的被動式RFID電子標籤。此系統晶片直接利用晶片內既有的密封環作為天線，與電子標籤電路整合在晶片上，不需外接天線，亦不需額外的晶片面積來放置天線，除了節省晶片面積亦可省下封裝及組裝的步驟，大幅降低電子標籤的製作成本。所提出的電子標籤電路將利用讀取器發送的60 GHz信號進行充電，充電完畢之後則會對讀取器發送的60 GHz脈寬調變(PWM)信號進行解調，得到輸入資料，最後電子標籤將內部資料以24 GHz頻率偏移鍵控(FSK)或背散射的調變方式回傳給讀取器。選擇60 GHz / 24 GHz的高頻訊號使得訊號傳輸不易受干擾，更可使接收天線的面積大幅縮小，資料傳輸速率加快；而選擇較低頻段的訊號回傳則可降低系統功耗。所提出的整合式電子標籤由於面積小、成本低，可使電子標籤的應用範圍更為廣泛，亦易於植入各項商品中，將可帶來商機。

Radio-frequency identification (RFID) is widely used in our daily life in recent years such as the access control, public transportation, electronic toll collection and many other applications. Antennas are required in RFID system for data transfer by radio-frequency electromagnetic fields. However, conventional RFID tags utilize external antennas which operate at low frequency and the external antennas size and costs limit the widespread adoption of RFID technology. To solve the antenna size and cost problem of conventional RFID tags, a passive RFID tag with the size of 1 mm2 is proposed in this thesis. The proposed RFID tag utilizes seal-ring which already exists in the integrated circuit chip as on-chip antenna that is not only integrated on chip but reduces large chip area to lower fabrication costs. The seal-ring antenna also has the advantage of eliminating the expensive packaging and assembly process and greatly reduces the costs of RFID tag. The RFID tag is wireless powered by the signals from RFID reader and then starts to demodulate the 60 GHz PWM signals to binary data as the tag possess enough power. Finally, the tag transmits output data back to reader by 24 GHz FSK modulation and backscatter modulation. Choosing high carrier frequencies as 60 GHz or 24 GHz has the advantages of protecting data transmission from interference, reducing the antenna dimension and allowing higher data rate. The proposed RFID tag is small-size and low-cost so that it allows extensive applications of RFID tag and brings unlimited business opportunities.