Low Phase Noise Lc Vco Design And Production

The goal of this subject is to sum up and exploit our technique how to produce low phase noise wideband VCOs ,through investigating and studying the basic theory and recent research fruits ,combining national condition ,and produce our low phase noise wideband VCOs .Using high Q components ,such as :coaxial resonator ,dielectric resonator , makes bandwidth of VCO become narrower ,so that recently common wideband VCOs generally make inductor and capacitor (LC) as resonators ,combining varactors with wide range tunable capacitance ,and achieve the wideband . At present ,I have carried out and finished the research and producing of low phase noise VCOs ,but the research of widebanth haven't gone deep(now can achieve normal level ) . In the course of the low phase noise research ,by integrating many aspects , using recent accomplishments ,I come up with my method and theory ,that by comprehending and controlling subcircuit of oscillator's resonator ,can let us know exactly their working states .Using this method and theory ,combining the VCO circuit of this subject ,I deduce and demonstrate particularly the reason of low frequency oscillation ,and come up with the measure of avoiding it .This makes design and producing VCOs can avoid the disturbing of low frequency oscillation ,and improve the features of VCOs .At later process of debugging VCO ,using this method makes the VCO achieves very good working state .The finished VCO ,its phase noise features are very good .At the conditions of free oscillation(not in PLL),high control voltage ,frequency 912MHz ,offset 10KHz from carrier frequency ,the phase noise is -105dBC/Hz ; After changing a better resonate inductor ,at frequency 781MHz ,offset 10KHz from carrier frequency ,the phase noise is -109dBc/Hz .Its wideband features isn't bad ,either .At present stage ,although I mainly want to test its features of low phase noise ,and haven't considered carefully its wideband features ,and haven't set aside enough space and suited structure on print circuit board to accommodate enough quantity of varactors ,so that the VCO's tunable frequency range and phase noise feature at wideband state have been limited .But now , at from 920MHz to 981MHz (60MHz) tunable frequency range , the VCO can achieve the phase noise feature of -100dBc/Hz offset 10KHz from carrier frequency .After changing the circuit board ,we believe the VCO can achieve higher features .Sum up ,the subject have obtained big progress .As the subject carries out deeper and deeper ,we believe the features of VCOs will be better.