The Design And Realization Of Broadband Frequency Source

With the development of semiconductor technology, frequency synthesis technology has also had a big progress from the initial direct frequency synthesis to indirect frequency synthesis and the latest direct digital synthesizer technology. The requirements of the frequency synthesizer for electronic systems has become stricter with the development of the technology. As the heart of the electronic systems, the performance of the frequency synthesizer will directly affect the performance of the whole system. This thesis presents the implementation of a 2.5GHz-14.6GHz ultra-wideband low phase noise frequency synthesizer.This thesis describes the development process of frequency synthesis technology, and describes the characteristics and key indicators of the frequency synthesizer in every stage of the development of the important frequency synthesis techniques, and then introduced the 2.5GHz-14.6GHz ultra-wideband frequency synthesizer demand indicators by analyzing indicators realize this frequency synthesizer need to use key technologies and methods.Through analysis, we finally choose the structure of using the PLL + DDS to realize the frequency synthesizer, through the analysis of phase-locked loop system, the phase-locked loop system can be decomposed into a phase detector, prescaler, fractional divider, oscillators, etc. The frequency step is mainly determined by fractional divider; stray mainly determined by the phase detector and the fractional divider; each part has a certain influence on the phase noise. Through the analysis of each section, we propose one or two options for each part.This thesis then design and implement the plan of each part we have analyzed before, and during the process of design, we confirm the alternatives, while give some supplement and changes to the unreasonable which did not noticed during the analysis. We also provide the details need to pay attention and the corresponding solving method of each part, and then provide the schematic and PCB board and physical map of each part. Finally we provide the design drawing of the shield cavity.According to the test, the frequency source satisfies the index of 1Hz frequency step, with spurs lower than-75 dBc and output power higher than 10 dBm. The phase noise of the frequency lower than-85dBc/Hz@10kHz through the whole frequency range.The end of the thesis introduce the deficiencies and the improving method of the frequency source.