3-6.2 Ghz High-performance Design And Implementation Of A Voltage Controlled Oscillator

Microwave oscillator is one of the most important components in mobile communication system and automatic measuring system.The noise,sensitivity and bandwidth of system are directly affected by the performance of the oscillator. As the mobile communication and automatic measuring system are developed quickly, system needs oscillators have broadband tuning range when oscillators have good phase noise and high power.The main contributions of this dissertation are presented as follows:Significance of research and the target of VCO (Voltage Controlled Oscillator) are researched, influence factors of the target are be given. Two kinds of wideband oscillators are researched,they are YTO(YIG Tuned Oscillator) and VCO.after they contrast is be given,we use the technology of VCO to design wideband oscillator,and the role and position of VCO in the spectrum are represented.The small signal Y, Z parameter and the large signal Y parameter are researched to analyse the distribution parameters of oscillator in stable state.with the ADS (Advanced Design System),the performances of some kinds of oscillators designed by distribution parameters are simulated.Based on the methods and significance for making a model to a transistor been introduced, models of a transistor named BFP520and a varactor named BB857are given.In addition, the key parameters which will influence the phase noise and frequency of VCO are analysed.After the phase noise theory of VCO was analysed,we get that the Q factor of resonator is the key parameter of phase noise,then,some kinds of resonator which can be integrated to plane easily are compared,and we design a kind of resonator with high Q factor named coupling resonator,the Q factor of coupling resonators is twice as much as ordinary resonators by calculated.With the ADS, the schematic and practical circuit diagram of the biasing circuit, resonator, tuned circuit, output filter and distributed inductance used to get negative impedance in VCO are simulated,and we get each network which are reached target of VCO,then the whole practical circuit diagram of VCO are simulated by using transient simulation and harmonic simulation. With simulation, the phase noise of VCO is better than-78dBc/Hz@10kHz, the power bigger than5dBm,the tuned sensitivity is better than300MHz/V.The VCO is debuged and the excellent performance of coupling resonator are checked.we get a high performance VCO worked in3to6.1GHz, the phase noise of VCO is better than-100dBc/Hz@100kHz, the power is bigger than2dBm, the tuned sensitivity is better than400MHz/V...