V. A. Romanyuk - Ph.D. (Eng.), Associate Professor, MIET (National Research University). E-mail: v.a.romanjuk@gmail.com Yar Zar Htun - Post-graduate Student, MIET (National Research University). E-mail: yarzarhtun2567@gmail.com

The paper proposes a design method of microwave voltage-controlled oscillators (VCO) based on the quasi-linear theory and modeling in Microwave Office program. The proposed method comprises the following steps: preparation and analytical calculation of the initial oscillator circuit; the oscillator circuit modeling in the linear operation mode of Microwave Office software and changing of the initial circuit settings for implementation of the possibility of the oscillations self-excitation in the desired frequency range; the circuit modeling in the nonlinear operation mode of the program and optimization of the circuit parameters for sufficient power of oscillations at the given frequency; complication of the oscillator circuit by adding a varicap and measurement of the VCO tuning characteristic; measurement of the VCO output waveform spectrum and the power spectral density of its phase noise; optimization of the circuit and its parameters in terms of \"minimum of normalized power spectral density of phase noise\" for a given oscillation frequency and power, as well as restrictions on the allowable voltages across the electrodes of the transistor. The paper presents the mathematical relationships by which you can configure the circuit for self-excitation in the desired frequency. The procedure of modeling and optimization of the microwave VCO circuit in the program Microwave Office has been described and the calculation of its essential characteristics has been given. The 18 GHz VCO electric circuit has been designed and optimized as an example.

 

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