If Digital Polyphase Filter Structure Of The Receiver

With the fast development of Software Radio technology, the wideband digital receiver systems are coming to play a major role whether in the communication systems or in the radar systems. It is expected to be designed based on the Software Radio technology in order to define the function of the hardware by the software, which can greatly improve the facility and the reliability of the systems. DDC (digital down converter) is a key technology in wideband digital receiver systems. However , because of the use of CIC filters in extant ASIC, it is usually very difficult to meet the requirements of wideband systems. Therefore, a method in design and FPGA implementation of wideband digital IF receivers based on polyphase filters to fulfill decimation and filtering is proposed. The results of computer simulation and FPGA simulation indicate that the technique is feasible and the experiment's results show that the performance of the system is excellent. In this paper, it summarize the basic principles of the IF (Intermediate Frequency) digitization technology and detail the design and FPGA realization of the digital IF receiver system.The main contents of this paper include: the theory of IF digitization (sampling, quantization, quadrature demodulation and multi-rate digital signal processing), the simulation of the system project, the design and implementation of the DDC part and introduction of the main devices applied in it.