L-Band Sub-Ouncer Low Phase Noise PLL Frenquency Synthesizer

The frequency synthesizer is the core of electronic system, widely used in the microwave communication, radar, navigation and instrumentation. The frequency synthesizer’s performance directly affects the performance of the entire electronic system. The phase-locked loop(PLL) frequency synthesizers are widely applied due to its excellent performance. The modern microwave electronic systems have much more requirement on the size and performance, so the research of low phase noise PLL frequency synthesizer with miniaturization size has become more and more critical.At present most of the traditional phase-locked synthesizer use PCB process with packaged device. That can’t meet the requirement on miniaturization and lightweight for modern electronic equipment. Below the frequency of S-band, the phase noise of monolithic PLL synthesizer is poor, can’t reach low phase noise requirements.In response to the above, to meet the needs of the project, this thesis accomplished L-band low phase noise PLL frequency synthesizer with in-depth theoretical analysis. The synthesizer has small size and good phase noise with software emulation to simplify the design process, has a good reference value for future design. The main difficulties of the design:1, PLL design; 2, the miniaturization process design; 3,design, simulation and debugging of low phase noise voltage controlled oscillator (VCO).This thesis reviews the development history of PLL frequency synthesizer first, and then expounds basic theory of it, and analyzes the principle of PLL synthesizer further. This thesis studies the reason of the phase noise of PLL synthesizer, and proposes several ways to reduce the phase noise of PLL synthesizer, which include increase the frequency of the phase, the appropriate loop and the usage of low-noise devices. On demand of miniature, it needs to develop the voltage-controlled oscillator (VCO) independently. This thesis analyzed the working principle and the structure of VCO, and derived the Leesson model of the phase noise, proposed design method of low phase noise VCO.Based on previous theory basis and needs of miniature, reliability, the circuit apply microwave thin film hybrid process, select low phase noise phase detector and perational amplifier die, simulate an active loop filter and low phase noise VCO accurately, design layout reasonable, we have designed and produced a hermetic, miniature and low phase noise PLL synthesizer, and tested the electrical specification of it. The synthesizer size is 21 x 15 x 4.1 mm3 and the phase noise is better than-105 dBc/Hz @ 10 kHz. This thesis analysis the test result, propose the problems of sample and further improve measures.