Design Of Voltage Controlled Oscillators Based On High-Q Tunable SISL Resonator

5G communication technology has the characteristics of high speed,large capacity,low delay,etc.,so it has a wide range of application re Quirements in the field of wireless communication.Voltage controlled oscillator is an important part of wireless communication systems,and its performance restricts the application and development of wireless communication system.As the operating frequency enters the 5G communication frequency band,the trade-off between wide tuning range and low phase noise noise in the design of voltage controlled oscillators has become increasingly serious.Meanwhile,in order to achieve low phase noise,most of the dielectric substrates with low dielectric loss and high prices are used,which leads to high costs of wireless communication systems.Based on the substrate integrated suspended line,this dissertation focuses on how to realize the low phase noise of voltage controlled oscillator with the advantage of wide tuning and low cost.First of all,aiming at the problem of low phase noise caused by the low Q of the resonator,this dissertation proposes a high-Q tunable split-ring resonator.By using weak coupling to increase the Q value,which can reduce the phase noise.The stepped impedance resonator is used to keep the second harmonic frequency away from twice the fundamental frequency and further reduce the phase noise of the voltage controlled oscillator.By loading the varactor on the high-Q tunable resonator to reduce the effect of parasitic capacitance of the circuit,which can broaden the tuning range of the voltage controlled oscillator.Experimental results show that the improved high-Q resonator has doubled the loaded Q value of the troditional split ring resonators.It has a tuning range of 320 MHz when the bias voltage is 0 V to 10 V.Secondly,in order to solve the problems of high cost,high phase noise,and narrow tuning range of the voltage controlled oscillator.Based on the above research,the high-Q tunable resonator is used as the frequency selection part of the voltage controlled oscillator to achieve low phase noise and wide tuning range.Benefitting from the substrate FR4,we can effectively reduce costs while maintaining high performance.The measured results show that the proposed VCO has a tuning range of374 MHz,and the phase noise is-122.81 d Bc/Hz@1MHz at 5.87 GHz.Finally,in order to further improve the phase noise and the VCO’s anti-interference ability,a low phase noise cross-coupled voltage controlled oscillator is designed based on the substrate integrated suspended line high-Q tunable resonator.The simulation results show that the phase noise is-134.561 d Bc/Hz@1MHz at 5.8GHz.