.8 ~ 18ghz Wideband Microwave Frequency Source Module

Direct Analogy Frequency Synthesis, Phase Locked Loop and Direct Digital Synthesis are three common frequency synthesis techniques. The said three techniques are comprehensively applied in the modern frequency synthesis technique, which are also called"Admixture-Frequency Synthesis Technique". This paper briefly introduces the basic theory of the technique and comes up with technical proposals of L-Band Frequency Source and 8~18GHz Frequency Source and demonstrates the feasibility of proposals.The L-Band Frequency Source applies DDS driving PLL circuit structure, which makes DDS and PLL complementary to each other, reaching the better technical index. The test result shows that the technical indexes of Frequency Source are: frequency range: 875MHz～1375MHz; step: 1MHz; spur: better than -80dBc; phase noise: -110dBc/Hz@100kHz; power: 4dBm±2dBm. 8-18GHz wideband frequency source applies DDS interpolation to PLL circuit structure as well as three common frequency synthesis techniques and replaces VCO with YTO to realize the output of broadband radio frequency. The frequency source adopts the idea of modular design. In accordance with its function, the circuit is divided into DDS,PLL,coupling, frequency division and filter circuits, which simplifies the circuit design and reduces the difficulties in debugging. The frequency source is controlled by FPGA. The test result shows that the technical indexes of Frequency Source are: frequency range: 8～18GHz; step: 100kHz; spur: better than -60dBc; phase noise: -70dBc/Hz@10kHz; transmission signal power: greater than 4dBm; local oscillator signal power: greater than 13dBm.This paper researches spur suppression of DDS, phase noise optimization of PLL, filter and power divider design, FPGA software control, establishment of automated test platform and design of the whole structure, which provides references for the further research of frequency synthesis techniques.