The Design And Optimization Of LC Voltage-controlled Oscillators

VCO(Voltage Controlled Oscillator)is the core block of PLL based frequency synthesizer. Its performance determines the whole synthesizer to a large extent. In many RFprecesses(GaA,SIGe,Bipolar,CMOS),CMOS Process is widely applied for its high integrated density and low cost.Therefore,CMOS VCOs on chip become the hotspot of many RF applications. It's difficult to fulfill the low noise and wide tuning range requirements with low power dissipation in VDSM.Firstly,the background and current situation of oscillator are introduced simply,the theory and parameters of the oscillator are presented, and a very vital parameter for voltage-controlled oscillators—phase noise is tudied.Secondly,for LC VCO, several common oscillator topologies are listed,their circuit structure have been given out and the analysis and comparison to their characteristics have been done out. In addition,the analysis procedure of design are introduced,an implementation and optimization of low phase noise,low power dissipation and wide frequency turning range in VDSM and low power supply LC VCO is proposed. In the end,to achieve the goal of low phase noise and low power dissaption,a pmos-core cross-coupled LC-VCO circuit is designed.The VCO circuit applies to the 2.4GHz wireless communications.Then the circuit is simulated with Spectre RF in SMIC 0.13μm CMOS process,the result indicate thatthe design has a Phase noise of -131dBc@1MHz . And the power dissipation of the circuit is only about 2mW, tuning frequeney range is2 .33GHz～2.57GHz and the layout of the related circuit is portrayed by means of the Virtuoso Layout Editor.we compare with similar designs on the references.This VCO has an excellent synthetical function and is able to be used in wireless communications technology, such as wireless digital audio frequency, wireless transmission (mouse, earphone )and bluetooth.