使用低溫共燒陶瓷技術設計與量測射頻模組

Abstract

目前低溫共燒多層陶瓷(LTCC, Low-Temperature Cofired Ceramics)技術的主要應用市場是在講究體積輕薄短小的可攜式產品上，是無線通訊模組的技術趨勢。此篇論文研究目的在於實現LTCC 射頻前端模組(RF Front End Module) 的縮小化設計與量測。在設計中，使用LTCC為基版將被動元件儘可能地設計於LTCC各層之中，並將主動元件及不易置入LTCC之元件置放於該LTCC上端，使所有的空間完全地有效利用，達到縮小化目的。設計上規劃的主動元件包含了一個射頻功率放大器及兩個射頻開關，其一開關作為發射接收切換，另一開關則作為天線分集使用，被動元件部分規劃了該射頻功率放大器的匹配電路與電源電路，以及一個帶通濾波器電路。初期以FR4的基版先量測主動元件之特性以及規劃的匹配電路驗證，以確保該系統工作狀態正常。進一步利用模擬軟體修正匹配電路上的偏差，以期達到原本的特性與效能。再使用模擬軟體將LTCC各層的佈局上巧妙地安排與空間上儘可能地有效運用，並要求特性上仍然保持原本的效能，符合 IEEE 802.11b/g的規範，最後以13層料片達成LTCC目標。在2.4GHz 產品設計整合上，輸入輸出埠的部份已從LTCC內部電路匹配到50歐姆的阻抗，因此提供更容易更快速地搭配整合晶片組及天線端接點，以便加速新產品開發。該LTCC射頻前端模組完成後，以OFDM模式測試，在EVM小於5%的情況下，天線端平均輸出功率達16.4dBm，電流消耗平均約200毫安培，平均增益為26.9dB，相對地發射器只要提供-10.5dBm的能量就足以推動。使用一家以IEEE802.11b/g為標準的晶片組結合測試，該資料傳輸率平均值21Mbps，與原本相同電路架構的產品可達到同樣的特性，並且大幅地有效節省82.4%的空間。

The major application and market place for Low-Temperature Cofired Ceramics (LTCC), is in the mini, portable electronic products. LTCC is the technological trend of wireless communication module. This thesis will describe the design method to minimize RF Front End Module of LTCC and measurement of the module. In this design, LTCC is used as a substrate, all non-passive components are integrated, as much as possible, in all layers of LTCC, while passive components and any components that cannot be easily integrated in LTCC layer are placed on top of the LTCC. All space will be effectively used, producing smaller module. The non- passive elements in this design include one power amplifier and two RF switches, one of the switches is used as transmit/Receive and the other for Antenna Diversity. The passive elements in this design include the matching and power circuits of the PA, and one band pass filter circuit. In the traditional way to use the FR4 as substrate, we need to measure the passive components circuit performance to confirm the matching circuit component value. This will prove the working performance. Then use the RF simulation software tool to prove the circuit. Use the software to simulate the different dialectical constant in the same type circuit structure. The above will achieve the design specification. If we use the RF simulation software and utilize the layout space, and keep the specification, that will match the IEEE 802.11 B/G specification. Finally when using the 13 layers LTCC, it can achieve the design specification when integrating the design into 2.4GHz product. The input and output port already matches the 50 OHM. Therefore, it could provide the easy and fast integration with the whole chip and antenna port. It can achieve new product development time, save man power and material. When this LTCC module assembled, use OFDM signal to test it when the EVM is less then 5%. We can achieve the average power of 16.4dBm, average current about 200mA, it is 26.9dB to average gain, so long as the transmitter is offered the power of -10.5dBm is enough to promote relatively. Use one to regard IEEE802.11b/g as the standard chip set to combine and test, this throughput of data average 21Mbps. The performance is the same as original FR4 board's product, and the total circuit size will be only 5.4 mm x 4.0 mm x 1.0 mm. To compare with the original, this can save around 82.4% of space.