The X-band Medium Oscillation Phase-locked Frequency Source Is Developed

Frequency source is an extremely important part of microwave electronic systems, such as radars and satellites, and it directly influences the performance of the whole system. With the development of the modern microwave technology, the demand for better performance of frequency sources is increasing. Therefore, it’s very important to study the technology of frequency synthesizing. Dielectric resonators have many advantages. The quality value and dielectric constant are high, the loss is low, and the temperature stability is very good. Frequency sources using dielectric resonators can realize low phase noise and high frequency stability in microwave band. Therefore, these frequency sources are widely used in microwave systems.Firstly, the basic theory of oscillators and how dielectric resonator works are described in this paper. Then, the coupling structures between dielectric resonator and microstrip line are analyzed in detail. Based on the theoretical analysis, the working principles of series reflective and parallel feedback dielectric resonator oscillators (DRO) are discussed. The two kinds of DROs are designed and realized through the simulation software. The design and debugging procedures are shared. This paper also realized another parallel feedback DRO using two stages amplifier in order to improve the performance. This kind of structure increases the gain of active network, decreases the coupling between dielectric resonator and microstrip line, and improves the loaded quality factor of the resonant network. So phase noise is lowered and the output power is increased. The DRO’s frequency is9GHz, output power is12dBm, phase noise is-80dBc/Hz@10kHz,-101dBc/Hz@100kHz, and the tuning range is15MHz, which meets the requirement.Then, the working principle of phase-locked loop (PLL) is introduced. After that, the design and debugging procedures of PLL are discussed in detail, and an X-band PLL frequency synthesizer is realized. The output power of the completed frequency source is10.5dBm, and phase noise is-93dBc/Hz@10kHz,-105dBc/Hz@100kHz, which meets the requirement of the project.