Learning by Simulations has been developed by Hans Lohninger to support both teachers and students in the process of knowledge transfer and acquisition . Click here for more information.

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The term "varactor" comes from the English expression for variable reactor and indicates semiconductor diodes, which utilize the dependence of the diode capacitance on the operating point of the diode. With varactor diodes, electronically tunable capacities can be produced, those, for example in tunable filters and oscillators (mobile communication), or for the frequency multiplication and frequency mixing. These are used in television tuners.

In practice, theoretical doping profiles as assumed by the simulation program can be obtained only with difficulty. Complicated diffusion processes cause non-constant concentration-dependent diffusion coefficients and therefore result in deviations from the ideal doping. Diodes are usually manufactured with complex technologies such as multiple diffusion or multiple implantation.

English version [309 kB]
German version [309 kB]
After downloading please unpack all files of
the zipped packages and start the executable.
The program "Varactor" allows to select from various doping profiles, spanning all commonly used concentration profiles, from hyperabrupt, over abrupt to linear. The corresponding characteristic of the diode is calculated and displayed. For downloading the program click on the little floppy disk symbols at right.

Last Update: 2012-Jul-14