Circuit Modeling of Varactor for Frequency-Agile Microwave Circuit Design

• Main Authors: Siang-Rong Hsu, 許向榮
• Other Authors: Nan-Wei Chen
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/90866660483748889769

碩士 === 元智大學 === 通訊工程學系 === 104 === The thesis proposes a quasi-lumped equivalent circuit of the varactor diode manufactured by Skyworks Inc., and the proposed model predicts an accurate response for wideband applications. Based on the manufacture's pure lumped equivalent circuit model, a lossy transmission line section, i.e. a distributed structure, is introduced to describe packaging parasitic effects and enhance accuracy of the device characteristics. The circuit parameters are retrieved by curve-fitting the measured scattering parameters of the varactor. Besides, the quality factor of the varactor diode can be extracted from simulated scattering parameters of the device model for analyzing varactor loss under different reverse biases. The model validation is carried out by an experimental verification with a varactor-based microstrip tunable bandstop filter and good agreement is observed between the simulated and measured results. Therefore, the proposed model can be used for characterizing varactor-based frequency agile RF circuits with a high accuracy.