Td-scdma Is The Transmitter Rf Circuit Design And Realization

In the year 2009, the Ministry of Industry and Information Technology issued the TD-SCDMA (Time-Division Synchronous Code Division Multiple Access), WCDMA and CDMA2000 3G's licenses to China Mobile, China Unicom and China Telecom, respectively. China Mobile got the home-grown 3G standard license of TD-SCDMA. Meanwhile, the other two operators were granted licenses for WCDMA and CDMA2000 respectively, which is the mark of entering the 3G age for China.Nowadays, the low power utilization efficiency of the base station results in energy waste, which become a prominent problem with the coming of the 3G era. In the base station, energy consumption of the power amplifier take a large proportion of its in efficiency, which is the main reason for the low efficiency overall. So, the key to raise the power efficiency of base station is to raise the efficiency of amplifier.In this paper, the RF circuit of TD-SCDMA's base station is designed and implemented, which including analog up-conversion and high efficiency power amplifier.Firstly, a detailed analysis of typical analog up-conversion schemes and several methods to improve efficiency of the power amplifier, in which we take IF signal orthogonal conversion and three-way Doherty scheme are adopted to meet the requirement.Secondly, the functional requirements of analog up-conversion were analyzed, and then the hardware circuits were designed and implemented by choosing the proper devices. Each module was tested and the results proved to satisfy the design specifications of TD-SCDMA RF transmitters.Finally, the analysis of design specifications of the final stage is made, based on which I completed the design of the drive amplifier and the simulation of three-way Doherty circuit of the final stage power amplifier and design the PCB.The dynamic range of analog up-conversion output is 31dB, which is larger than the system need 30dB, with the ACLR ?53.91dB@?1.6MHz and ?55.43dB@?3.2MHz in TD six carrier conditions were prior to the system need, 45dB and 47dB. The simulation results of three-way Doherty was greater than 46% at the output power is 43dBm, 6 percentage points higher than the target percentage—40%. The design in this paper could be used as TD-SCDMA's base station RF circuit, which is of great value.