Design Of 5GHz LC VCO Based On Silicon

Phase-locked loop(PLL) is one of the most important parts of the radio subsystem. On the other word, PLL is the core of the whole system. Voltage Controlled Oscillator(VCO) is the most significant component in the PLL and one of the core modules in the RF transceiver, it is very important.Voltage-controlled oscillator(VCO) can transfer the RF signal spectrum and choose the appropriate channel by generating the local oscillation signal. The selection of oscillator frequency and the applicable scope are controlled by the tuning range and the sensitivity of VCO is dominated by the oscillator phase noise performance. VCO increasingly focused on much higher standard of phase noise recently.Under the development trend single chip system integration which is compatible with a variety of wireless communication protocol, the design of the VCO is higher and higher standards. This paper aims at designing a VCO which of local oscillator signal can cover a 4.6 to 5.4 GHz in the view of Wi MAX spectrum in the application of 2.3 to 2.7 GHz.Firstly, this thesis reviews the development and researches on the oscillator and the development is also analyzed.Secondly, the working principle, design focus and performance requirements are introduced, mainly on the theory of phase noise. Finally, it refers to the detail in designing and simulating of LC- VCO.In this thesis, the device model adopted the TSMC 0.18 um CMOS technology is used to design the circuit, and the simulation is carried out with the aide of Cadence Spectre simulation software. This oscillator utilizes a NMOS cross couple structure, a 5 bit switched capacitor array used to extend tuning range, which makes KVCO at a low value to effectively reduce VCO's phase noise. In the end, the designed VCO meet the design requirement and taped, which of tuning range from 4.5 to 5.5 GHz, the area of the map 0.147 mm2, power consumption less than 10 m W, and its phase noise only- 122 d Bc/Hz @ 1 MHz in the 5 GHz.