to provide better performance than p channel devices in this example for positive i tbu i e in direction of i tbu arrow transistors q 8 and q 9 cooperate to provide transient blocking for negative i tbu transistors q 7 and q 9 cooperate to provide transient blocking more specifically for negative i tbu exceeding a predetermined first threshold a voltage between terminals t 1 and t 2 provides a voltage at g 3 tending to switch off q 9 which then acts to switch off q 7 thereby shutting off the tbu similarly for positive i tbu exceeding a predetermined second threshold a voltage between terminals t 3 and t 4 provides a voltage at g 4 tending to switch off q 9 which then acts to switch off q 8 thereby shutting off the tbu diodes d 1 and d 4 act to block current flow to or from the gates of q 7 and q 8 in some cases the voltage handling capability of the gates of q 7 and q 8 may be insufficient to handle the high voltage developed across q 9 in such cases resistance can be included in series with diodes d 1 and d 4 or as a replacement to the diodes to ensure the bypass current generated by this high voltage is limited to a.