X-band Low Phase Noise Dro Frequency Source

The increasing development of modern communication systems demands for frequency synthesizers with excellent frequency stability, low phase noise and wide frequency range. In the single-frequency output synthesizer technique, dielectric resonator oscillators (DRO) make use of dielectric resonator (DR) of high quality value, high dielectric constant and low loss, and it is able to realize relatively low phase noise in microwave range. Sampling phase locking technique combines the advantages of multiplying reference signal from crystal oscillators and digital phase locked loop; therefore, it features simple structure, high-order multiplying and low phase noise. Sampling phase locking technique can be used to detect the phase of a voltage controlled DRO at high frequency; since it gets rid of the frequency divider part in the phase locked loop, it is able to realize microwave frequency synthesizer of high frequency stability, low phase noise and low cost.The main purpose of this dissertation is to realize the design of an X-band sampling phase locked DRO. It contains three tasks: measurement of dielectric resonator materials, design of X-band DRO and design of sampling phase locked DRO.First, the dielectric resonator method is used to measure microwave dielectric materials. In previous DRO designs, coupling model of dielectric resonator and microstrip is either from software itself, or is constructed in simulation software using DR parameters provided by the manufacturers. When the model is not accurately constructed, it brings trouble to the DRO design in simulation software as well as to the debugging process. Using the measuring system mentioned in this dissertation, electrical parameters of DR such as dielectric constant(εr), dielectric loss angle tangent(tanδ) and resonate frequency are measured precisely, providing the basis of constructing accurate coupling model in simulation software.The second task is to realize design of X-band DRO. Through comparison and analysis of structures and theories of commonly used DRO schemes, this dissertation uses parallel feedback structure to fabricate three X-band DROs. This dissertation uses EDA software to design the DRO, the process of which is introduced in detail. The three DROs are tested and methods of further improving the performance are presented.The last task is design of sampling phase locked dielectric resonator oscillator. Through debugging of the sampling phase locking loop, an X-band sampling phase locked DRO with good phase noise performance is achieved. After comparing it with other designs in reference papers, this dissertation raises some methods to optimize the design and further reduce the phase noise.