Research And Design Of Wideband RF Front-End Of TD-LTE Base Station Receiver

The cable network communications have been developed from the 14.4 Kbps dialup Internet access to now the 100 Mbps fiber, while the 1 G to 4 G wireless mobile communication is also an inevitable trend. TD-LTE, which has been jointly explored by the several major industrial companies, is a communications technology standard of 3GPP, and also is a branch of the long-term evolution(LTE). The TD-LTE with the capability of offering 100 Mbps downlink and 50 Mbps uplink data communication under the 20 MHz spectrum bandwidth, can provide faster than 100 Kbps access services for 350 km/h high-speed mobile users. It can greatly improve the speed of data transmission and also has a further improvement in the aspect of the spectrum utilization; at the same time, it can make 4G and 3G realize the smooth transition. Orthogonal frequency division multiplexing(OFDM) technology replaces the code division multiple access(CDMA) technology in the LTE, which makes LTE be well against multipath interference. It can support six different bandwidths flexibly. Because high data transmission rate is the feature of the 4G wireless systems, the performance requirments of the receiver should be much higher. Therefore, high-performance RF receiver is the key to supporting these technologies.In this thesis, the research object is the base station receiver of TD-LTE. According to the technical specifications and requirements of 3rd Generation Partnership Project(3GPP) to LTE, the design of TD-LTE base station RF broadband receiver unit circuit can be realized. In this design, the receiver is the digital intermediate frequency structure with 2500-2690 MHz of radio frequency band, 60 MHz of the intermediate frequency(IF) bandwidth and 230.4MHz of the center frequency. This thesis introduces the definition of base station as the breakthrough point to discuss base station RF system structure, followed by the discussion of the advantages and disadvantages of various architecture receiver. Then it elaborates the RF performance index of 3GPP to wide-area base station in detail, and analyzes the important parameters quantificationally in the end. Linking budget according to the parameters, with which is complied strictly, the device selection and circuit design of the receiver can be fulfilled. Compared with the expected index, the final test results are consistent with the link budget index by testing the whole parameters index of link. The innovative ideas show that receiver can still keep the good radio-frequency performance after the bandwidth becomes wider. The circuit can be applied to the 4th generation mobile communication base stations of China Mobile, China Telecom and China Unicom by changing the frequency of its local oscillator. What’s more, the throughput capacity of system can be enhanced by the intermediate frequency bandwidth of 60 MHz which has some reference value to the application research of this domain.