Low Phasenoise High Linearity Voltage-Controlled Oscillator Research And Implementation

The voltage-controlled oscillator(VCO) is an important part of the phase-lockedloop(PLL). It is widely used in communication products such as mobile phones, digital TVsand navigation terminals. Its phase noise determines the performance of the entirecommunication system. With the advances in CMOS microelectronics technology and radiofrequency (RF) technology, it is possible to integrate the voltage-controlled oscillator andother RF circuits in a single chip. In the process of integrating, the low quality factor ofCMOS integrated inductor and the flicker noise of MOS transistor cause poor phasenoise inthe VCO. At the same time, serious nonlinear characteristics of CMOS varactor leads to poorstability of PLL. Therefore, a VCO with low phase noise and high linear Kvcohas greatpractical value.This thesis designs a fully integrated LC tank VCO used in PLL based on TSMC0.13umRF process. The oscillator resonant frequency of4959.02MHz.The circuit applies a newarchitecture of VCO without tail current source to reduce the phasenoise. As is required byPLL loop stability, in order to improve linearity of Kvco, this thesis adopts an optimizedvaractor array. Layout simulation results show that the phasenoises at4959.02MHz are-74dBc/Hz offset10kHz and-97.7dBc/Hz offset100kHz. The tunning range of VCO is up to12%and the change rate of Kvcoof the voltage controlled oscillators in the sub-band is below10%.