Diode-triggeredsilicon-controlled rectifiers(DTSCRs) are used for on-chip electrostatic discharge protection. The role of the trigger diode string in determining the transient voltage overshoot is investigated using a very fast transmission line pulse. A DTSCR containing only poly-bound trigger diodes has a voltage overshoot of just 1.5 V at 7 A, which is significantly less than what is found with STI-bound diodes. A DTSCR with only STI-bound trigger diodes has a lower leakage current. Therefore, DTSCRs with different trigger diode configurations may be suitable for different applications, e.g., high speed or low power.