Optimization of RF front end circuit for IMT-Band

• Main Authors: Chi-hung Wu, 巫奇紘
• Other Authors: Jia-chin Lin
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/75391870385223084008

碩士 === 國立中央大學 === 通訊工程研究所碩士在職專班 === 100 === In this thesis, the SAW filter of RF front end circuit was eliminated, it would save area on the PCB as well as cost. The transmit frequency lies between 1.92 and 1.98GHz, receiver frequency lies between 2.11 and 2.17GHz, which meets the bandwidth specifications for WCDMA and LTE systems. According to the 3GPP specification, the Rx sensitivity within BER test of CMU-200 (Rohde & Schwarz) cannot exceed -106.7dBm. The research would use surface mount device (SMD) and a multilayer PCB to make sub-circuits. After the elements of sub-circuits have passed measurement and performance tests, we combine the elements on multilayer PCB. Low cost and small size are to be expected from circuits. Our design seeks to implement the best solution. The transceiver of the RF front end circuit includes antenna switch module, power amplifier, SAW filter, duplexer and transceiver. Assume, the SAW filter is existed from the Tx chain and the noise figure is 5.5dB. The receiver sensitivity is -112.2dBm; Assume, the SAW filter is removed from the Tx chain and the noise figure is 8.3dB. The receiver sensitivity is -109.4dBm. Tx to Rx desensitization occurs because the transmit noise in the Rx band leaks into the Rx chain and effectively increases the noise figure of the Rx; the perspective of improving the performance of the duplexer from the Tx and the noise figure is 5.8dB. The receiver sensitivity is -111.9dBm. After the integration test combining all the elements of sub-circuits, the result of all Rx channel measurement covering 2.11 to 2.17GHz for IMT band. Sensitivity measurements can be made by using the CMU-200.The full suite of Rohde & Schwarz CMUgo measurement is available for analysis. When the SAW filter is existed, the mean value of receiver sensitivity is -111.94dBm. When the SAW filter is removed, the mean value of receiver sensitivity is -109.59dBm. Improving the performance of the duplexer, the mean value of receiver sensitivity is -111.75dBm. From the above-mentioned, measurement values and equation value are the same result.