Automatic Measurement System Of Varactor Characteristic Parameters

As tuned reactance component, varactor has been used extensively in automaticfrequency control, oscillator circuits, frequency modulation and many kinds ofcommunication systems. Product parameters can be always obtained from data sheetprovided by suppliers, but there is a question that these parameters are suitable for low andmedium frequency circuit, such as KHz and MHz. As extensive use of RF application,when simulating RF circuit containing varactors like voltage controlled oscillator at3.4GHz, fundamental radio frequency parameters of varactor are also necessary to assureaccuracy. Design of the testing platform to abstract RF parameters of varactor is necessaryand significant work. However, there are so many disadvantages in traditional manualtesting method such as complex test process, low efficiency and other interference. Hence,the development of automated testing software has received extensive attention in testindustry due to that it makes testing work simple and convenient.The simulation and manufacture of testing platform based on microwave theory hasbeen introduced firstly in this paper. Then a general capacitor was used to verify thereliability and veracity of testing platform and make foundation for varactor testing.Then the remote control technology of vector network analyzer was researched particularly.Software VB programmed to display the interface of automatic measurement system. Atlast, automatic measurement system was formed including testing platform andmeasurement interface. The system is simple and convenient to operate, while results willbe saved as report and this can avoid manual data record.The thesis is divided into three parts. The first part is microwave theory. In this part,analysis methods of microwave network are given firstly, singe port and double port arediscussed here.Key points in this part are scatter matrix and transfer matrix as theoryfoundation for next part. The second part is the simulation and fabrication of testingplatform. Structure of testing platform composed by transmission line and stub is givenfirstly. Testing function and method of parameter abstracting is discussed by theory abouttransmission line. Size of platform is determined after simulation with HFSS andfabrication of platform are introduced. Nextly, a general capacitor is used to verify the reliability and veracity of testing platform,and results show that it is valid. The last part isdesign of automatic measurement system. In this part, the remote control technology ofmeasurement equipment and the hardware of this system are discussed firstly. The detaildesign process of system’s software is given secondly. The communication buildingprocess between computer and network analyzer and the design of functional modules inthe system are especially focused on. For every module, this part gives operating interfaceand introduce. Finally, varactor called BBY51-02W is measured by this automaticmeasurement system. Report of measuring results formed as word is generated and savedautomatically by system.This paper proposes varactor testing platform and achieves remote control of vectornetwork analyzer by software VB to program interface. The whole automatic measurementsystem of varactor RF parameters is accomplished and provides a reference for theachievement of other microwave automatic measurement system.