Study And Design Of Low Phase-noise Voltage Controlled Oscillator Based On SISL Technology

With the wide application and continuous innovation of wireless communication technology,people's communication quality and communication speed requirements are getting higher and higher.Therefore,high performance RF transceiver,which is the key module of wireless communication system,is highly demanded.Signal source is a key subsystem for RF transceiver,because its phase noise is a critical specification that affects the dynamic range and sensitivity of a transceiver.As one of the main contributors to the phase noise of a signal source,the design of a low phase noise voltage controlled oscillator(VCO)is significative to improve the performance of wireless communication system.It is known that the phase noise of a VCO depends dominantly on the Q factor of LC tank or resonator.Therefore,the use of a high-Q resonator is an effective way to improve the phase noise performance of VCOs.Due to the features of low loss,substrate integrated suspended line(SISL)is conducive to the design of high-Q passive circuits and resonators,and the circuit based on SISL has the advantages of small size,self-package,easy integration,etc.Therefore,this thesis uses the advantages of SISL and combines with the technique of reducing phase noise to design a low phase noise VCO besed on SISL.The main contents of this thesis are as follws:In the first chapter,the literatures of board level low phase noise VCO are studied.Then the topology of the board level VCO and the methods to reduce the phase noise are summarized.In the second chapter,based on the theory and analysis models of oscillators,the starting conditions and stable conditions of oscillators are analyzed.After that,the definition of the main performance indexes,including the phase noise,which is the most important specification of VCO is introduced.The major methods to reduce the phase noise of VCO are given by analyzing the basic principle and Leeson model of the phase noise.The third chapter introduces the SISL,highlights the adantages of SISL by comparing with the plane transmission line and traditional waveguide suspended line,and proposes to use SISL based high-Q resonator to reduce the VCO phase noise.Based on the above theoretical research,the fourth chapter focuses on the design of SISL low phase noise VCO.As an expansion,the influence of different implementations of ?g/2 resonator on SISL to the phase noise of oscillator is also studied in the chapter five.In this thesis,ADS is used to sumulate the circuit schematic and layout of SISL VCO.The measured frequency tuning range of the proposed VCO is from 4.08 to 4.25 GHz with a 4.1% bandwidth.Over the operating frequency range,the phase noise is better than-130.2 dBc/Hz at 1MHz offset frequency,the output power is higher than 4.64 dBm,and the FOM of SISL VCO is 192.1 dBc/Hz.When Vt is set to 6 V,the beset phase noise of-132.1 dBc/Hz at 1MHz offset from 4.167 GHz is obtained.Compared to other board level VCOs,this work not only has low phase noise,but also has compact size and features of self-package.