Abstract: The transient resistance,voltage,and power of a nonlinear GaAs photoconductive semiconductor switch (PCSS) are presented by the finite difference formula to deal with the experiment data,based on the conversation of energy in the switch circuit.This method resolves the problem of directly measuring the transient characteristics of PCSS in nonlinear mode.The curve of transient voltage shows that the average electric field of PCSS in the lock-on period is always higher than the Gunn threshold,and increases monotonically.By comparing the transient power curves of the PCSS and the electrical source,it is demonstrated directly that the power shortage leads to the PCSS from the lock-on state into the self-turnoff state,so a controllable turnoff of the PCSS in lock-on by changing the distribution of the circuit power is predicted.

Key words: photoconductive semiconductor switch, lock-on effect, nonlinear mode, controllable turnoff