The Study, Based On The Linc System Demultiplexer

The information transmission technology of modern communication system is developing rapidly in direction of multi-carrier,multi-level,broadband and high Peak-Average-Ratio(PAR).New broadband digital transmission techniques(such as OFDM and WCDMA)and high spectrum efficiency modulation techniques(such as QPSK and M-QAM ) are extensive used. These high efficient multi-carrier & multi-channel digital modulation transmission techniques, which are based on non-constant envelope, request high linearity of radio frequency power amplifiers(RF PAs). When signal is amplified by RF PAs, intermodulation distortion is generated, which results in spectral regret, then lead to adjacent channel interference. In modern wireless communication system, adjacent channel interference has got stringent restrictions, for instance, according to 3GPP WCDMA specification, if the adjacent channel power is greater than -50dBm then the Adjacent Channel Power Ratio (ACPR) shall be higher than the value of -33dBc@5MHz and -43dBc@10MHz. Furthermore, power amplifier also need give attention to high efficiency in wireless communication system, the linearization to high efficiency in wireless communication system, the linearization technique for RF PAs is necessary.LINC transmitter is linear transmitter in substance, which can overcome the disadvantages coming from the amplifier's nonlinearity. It can use the high-efficient nonlinear amplifier. This paper studied the design and implementation of SCS,which is the most important part of LINC transmitter. Based on the analysis of SCS realization architectures, the arithmetic simulation using MATLAB has been studied, and with the simulation results and theoretic analysis, the final architecture and data resolution of SCS has been decided. Then the FPGA design and realization of SCS has been researched. In order to improve the speed and performance of SCS, from the structure of FPGA, the pipelining technology and LUT technology have been studied to improve the speed and save hardware resources. These have been validated by MATLAB simulation and Verilog HDL program. Compared with the test results using frequency spectrum analyzer and oscillograph, the design is correct, and can meet the request. For the complexity of the design and the short of time, there still something else has not been finished completely, for example the accurate effect of the bandwidth after SCS and how to reduce this effect etc. The next work is to research the effect caused by SCS on the LINC system, and refines the design.