Design Of Low Phase Noise Oscillator Based On High Q SISL Cavity Resonator

In recent years,the application requirements such as 5G communication and IoT have put forward higher requirements on the performance of RF front-end circuit modules in wireless communication systems.In the RF front-end circuit,the oscillator as a device which provides local signals in the transmit and receive links,and its phase noise directly affects the speed and accuracy of the system's received signal.Therefore,the research of high performance oscillator is a valuable topic at present.On the premise of detailed analysis of the working principles and the phase noise models of oscillator circuit,based on the platform of Substrate Integrated Suspended Line(SISL)technology,this paper makes full use of its advantages of low loss,multi-layer wiring,high integration and self-packaging.The high Q SISL cavity resonators are presented and verified,and the low phase noise oscillators are proposed based on SISL high Q cavity resonators.The main work and innovations of this thesis are as follows:1)The typical structure of the SISL technology and its advantages in the application to the circuit are introduced in detail.For the first time,the air cavity in the SISL structure is used as a resonator to realize a high-Q SISL single metal cavity resonator(SMCR),and the test QL of this resonator can achieve 495.2)On the basis of making full use of the low radiation loss property of SISL cavity resonator,combing the advantages of the multi-layer and double-layer wiring of SISL,the Q-enhancement technology of the SISL cavity resonator is proposed based on detailed theoretical analysis.From the perspective of reducing dielectric loss and conductor loss,the SISL SMCR with substrate partly excavation and the SISL double metal cavity resonator(DMCR)with substrate partly excavation are designed and fabricated.The test results show that the QL of the above resonators are 639 and 792,respectively.Compared with SISL SMCR,the QL of the reaontor is significantly improved.3)A low phase noise oscillator adopting SISL SMCR as the frequency selection network based on the series feedback topology is designed and fabricated.The test results show that this oscillator has an oscillation frequency of 12 GHz,and a phase noise of-128.91 d Bc/Hz at 1MHz offset with the output power of 4.9d Bm.This SISL oscillator has the advantages of low phase noise,low cost,high integration,and self-packaging.As a comparative verification,the SISL SMCR with substrate partly excavation and the SISL DMCR with substrate partly excavation are also applied to the oscillator circuit.The test results show that phase noise at 1MHz offset of the oscillators adopting the above two resonators are-131.41 d Bc/Hz and-133.91 d Bc/Hz,respectively.By increasing the Q value of the SISL cavity resonator,the phase noise of the oscillator is significantly reduced.4)By coupling a varactor inside the SISL cavity resonator,a widely-tuned resonator is proposed.When the tuning voltage changes from 0V to 20 V,the resonator achieves a wide tuning range from 10.75 GHz to 11.74 GHz,which can be used in a widely-tuned voltage-controlled oscillator circuit.