Design Of Fractional Divider And Voltage Controlled Oscillator Based On SiGe Technology

In the past hundred years,the field of wireless communication has experienced rapid development,the application of wireless communication technology has become more and more extensive,to today,wireless communication has been like "electricity" into people’s daily life.For a wireless communication system,the frequency synthesizer is an indispensable and important part.At present,the implementation of frequency synthesizers based on phase-locked loops is a more mainstream choice in the field of wireless communication.This synthesizer consists of multiple core circuits,of which fractional dividers and voltage controlled oscillators are two important components.Fractional dividers achieve fractional ratios to improve the frequency resolution of frequency synthesizers.Voltage-controlled oscillators directly affect the tuning range and phase noise of the synthesizer.The excellent fractional divider and voltage-controlled oscillator are prerequisites for the realization of a high-quality phase-locked loop synthesizer,so they are of great significance in the field of wireless communication.This thesis first briefly introduces the structure of several frequency synthesizers,focusing on the basic concepts of phase-locked loop synthesizers.Next,the working principle of the fractional divider is briefly explained,the mechanism of fractional spurs is explained,and two common methods for eliminating fractional spurs are compared.After comparison,the Sigma-Delta modulation technique was chosen to suppress fractional spurs.The fractional divider in this thesis consists of a 3rd-order MASH1-1-1structure Sigma-Delta modulator and a multimode divider based on TSPC structure.The fractional divider works under 1.5V voltage,when the input frequency is between1GHz～3.3GHz,it can work normally,the input width of the fractional is 18 bits,the frequency resolution is 2.441 k Hz,and the range of divider ratio is 35～60.At the same time,this thesis analyzes the implementation principle of oscillator,compares various structures of oscillator,explains the basic working mechanism of voltage-controlled oscillator,and realizes a differential Colpitts voltage-controlled oscillator on the basis of Colpitts oscillator.Finally,based on the 130 nm SiGe process,the layout of the Sigma-Delta modulator in the fractional divider and the differential Colpitts voltage-controlled oscillator are realized.Due to the incomplete processing of the phase-locked loop containing a decimal frequency divider,only the actual test results of the voltage controlled oscillator are provided in this thesis.After testing,the output frequency range of the voltage controlled oscillator is 37.109GHz～38.113 GHz,and when the center frequency is 37.1096 GHz,the phase noise of the voltage controlled oscillator in this thesis is-102.94 d Bc/Hz at a frequency offset of 1MHz.