The Design Of S-band Laminated SIW Voltage-controlled Oscillator

Frequency source is a key component of radar and modern communication systems, it is the origin and reference standard of the signal pulsation in the whole communication system, however oscillator is the core component of frequency source, so it has great influence on the performance of the whole communication system. With the continuous development and progress of the electronic system, it requires the oscillator having small size, low phase noise and high reliability characteristics. Whereas the novel substrate integrated waveguide(SIW) cavity that can realizes smaller size and has high quality factor being used to design oscillator can not only verify the role of SIW theory, but also has a high research value.This thesis summarizes the research development of SIW oscillator in recent years at home and abroad. Then it makes in-depth analysis on the working principle of feedback oscillator and negative resistance oscillator, expounds the reason and influencing factors of the frequency stability and phase noise, then focuses the analysis on the transmission properties of SIW structure, describes the relationship between FSIW’ cut-off frequency and the gap of middle metal layer slot, summarizes the transition modes between SIW and transmission line, analyzes the SIW cavity resonant mode and frequency characteristics briefly, and introduces the laminated SIW cavity briefly.Then this thesis compares the miniaturization degree of L-type slot SIW cavity, Ctype slot SIW cavity and double L-type slot SIW cavity to traditional monolayer SIW cavity by simulation. It finds out that C-type slot SIW cavity can minimize resonant frequency in the same area. And the resonant frequency can be continuously adjusted by changing the length of the short side of middle layer slot. Based on that, we design and simulate four coupling ways of the laminated SIW, and through the comparative analysis find that the probe of greater area has the stronger coupling between the cavity and the top circuit, and the effect of voltage probe’ area on the coupling strength is very large, while the size of current probe only slightly affects the coupling strength.Based upon these, we place active circuit on the C-type slot SIW cavity to design four kinds of laminated SIW voltage-controlled oscillators through the four coupling methods. And we focus on the design and fabrication of the four kinds of oscillators, analyse the principle and function of each part of the principle diagram, including the selection of components, the design of the bias circuit, the design of the negative resistance circuit and the design of reducing the power supply noise and attenuation circuit. Finally, each oscillator has been separately carried on the simulation and actual test, and comparison analysis and summary.In this thesis, we through two ways to realize the miniaturization of S-band laminated SIW voltage-controlled oscillators, one is to use the C-type slot SIW cavity, which has a high degree of miniaturization, the other is to superimpose the active circuit part on the cavity completely for further reducing the area. Finally the four kinds of designed voltage-controlled oscillators have the same small area of 10mm*10mm, the output frequencies are 3.484~3.55 GHz, 3.50~3.526 GHz, 3.48~3.497 GHz, 3.457~3.478 GHz respectively, and the phase noise at 100 k Hz offset of oscillation frequency is-100.18 d Bc/Hz,-111.11 d Bc/Hz,-114.42 d Bc/Hz,-112.66 d Bc/Hz respectively.