X-band Microwave Local Oscillator, Digital Circuit Design

With the development of science and technology, the system of microwave local oscillator source is becomeing increasingly demanding, mainly in the stability, accuracy and phase noise, while the traditional method of frequency synthesis can not meet the actual requirements. Therefore, the research of high precision and high stability microwave local source technology has become an urgent mission.The main subject of the article is studying the digital circuit of high performance X-band microwave local oscillator source. The article analyzes three commonly used frequency synthesis methods, according to the requirements of the article's target and considering from the overall of the system, and determine to adopt the DDS integrate chip to complete the design of the local oscillator source. On the basis of analysis of the performance of the key devices AD9851, ADF4106 and XC3S200, the thesis indicate the total design scheme of X-band microwave local oscillator source. The thesis also shows the function of the DDS module, FPGA module, serial communication module, filter module, amplitude module and power module, and designs the circuit schematic diagram, and the PCB of the digital control circuit of the local oscillator source.The paper completes the initialization of AD9851, the transmit of the control words, the FPGA program design and simulation sending and receiving of serial port in the circumstance of ISE by using Verilog language. The paper also indicate the software flow chart, design process and simulation result, which demonstrates the correctness of the design.