Photoconductive semiconductor switches made from semi-insulating (SI) GaAs material using the deep donor shallow acceptor (DDSA) compensation technique have been analyzed to account for premature break-down that has been demonstrated in experiments. Analyses show that in the "on" state the conduction process is filamentary in nature and at high bias conditions, due to the rapid formation of trap-filled regions, the homogenous nature of the device changes, thus affecting the conduction process and resulting in breakdown. An n(+) layer next to the negative electrode has been found to suppress carrier injection and the formation of trap-filled regions, consequently allowing for higher voltage operation. Higher voltage device operation has been found to lead to faster risetime switching, an important factor for ultra-wideband radiation generation.