Ka-band Vco Design And Closed-loop Linear Correction

As a key component of the millimeter wave (MMW) frequency-modulation systemfor measuring distance, the MMW VCO (Voltage Controlled Oscillator) has a great effectupon the range and accuracy of the distance measurement. In this paper, the Ka-band VCOis designed, and an analog closed-loop linearization system is used to improve the linearityof the VCO.Based on the work carried out by former researchers, the circuit model of thelongitudinal configuration of the varactor and Gunn diode along with the waveguide cavityis used to design the VCO, the height reduced waveguide is used for the main cavity, andthe structure of coaxial lowpass filter is used for the DC biasing circuit. The size of theVCO is 29×16×16mm, and the output power is no less than 40 mW.Reactance compensation, open-loop and closed-loop linearization are investigated,and the analog closed-loop linearization system is used to accomplish the linearization. Bycompleting the index of the PLSL and designing the key Circuits as loop filter; low-passedfilter, triangle wave generator, etc., the linearity of the VCO can reach 0.3％.