Small-Signal Fractional-Order Model of PN Junction Long-Base Diode

Most models of PN junction diode are mathematical models rather than circuit models, and there is a necessary trade-off between model versatility and accuracy. The small-signal fractional-order circuit model of PN junction long-base diode based upon the device’s physical operating principles and fractional-order vector fitting is obtained. This model consists of fractional elements and traditional elements; at the same time, the conventional diffusion model, that is two-element diode model, is included as a special one. In particular, only two model parameters, inverse saturation current and minority carrier lifetime of the PN junction diode, need to be extracted for formulating fractional-order model. And it is proved that the simulation effect is perfect by comparing the normalized admittances of different diode models. So the efficiency and accuracy of the model can be greatly improved compared with the high-speed dynamic model of PN junction diode. The presented equivalent model is shown to be capable of reproducing the frequency-dependent characteristics of PN junction long-base diode, and it can be applied to different small-signal circuit environments. Finally, experiment of junction diode can also validate the efficiency of the small-signal fractional model.