Modeling the Performance of Electromagnetic Pulse Generation Circuit Based on Avalanche Transistor Switches

The output waveform of the electromagnetic pulse generation circuit (EPGC) with avalanche transistors as a switch had a rising edge of hundreds of picoseconds, and its spectrum covered tens of megahertz to several gigahertz. The EPGC was integrated with a printed circuit board, the size of which was several centimeters. The size is comparable with the wavelength of the corresponding pulse spectrum, so the traditional lumped parameter circuit analysis method is no longer suitable. This paper proposed a technique of co-simulation using physical models of avalanche transistor semiconductors and circuit board microstrip line equivalent circuit models. We introduced the transistor physical model, printed circuit board equivalent model, and LRC (inductance, capacitor, and resistor) components into the TCAD software to simulate the output characteristics of the EPGC of the avalanche transistor. Based on the experimental measurement data, we have verified the proposed model's effectiveness by comparing several methods for the simulation of output pulses of the EPGC. The results showed that the proposed model was more than ten times more accurate than the traditional method for waveform amplitude simulation. In addition, the switching-on process of the first-stage avalanche transistor mainly determined the delay stability of the output pulse of the solid-state pulse source. The maximum transistor hot spot is located at the interface of n
0
-n
⁺
in the collector. The first stage avalanche transistor had a smaller temperature rise and higher thermal reliability. Therefore, we could shorten the design iteration period of the electromagnetic pulse generation circuit based on the proposed model.