New type of varactor diode having strongly nonlinear C-V characteristics

A study of a new type of varactor diode which consists of a semiconductor multilayer structure is reported. This varactor diode has much stronger nonlinearity in capacitance variation with applied bias voltage than does the conventional varactor due to the two-dimensional expansion of the depletion region. First, the internal behaviors of this diode are investigated in detail by two-dimensional computer simulation. With the aid of those results, an approximate analytical expression for the voltage dependence of capacitance is derived for the purpose of practical design. Then experimental studies have been performed using Si, which substantiate the theoretical predictions.