By Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Commercial sub-nanosecond pulse generators allow the change of amplitudes and widths of generated pulses, and offer features such as generating single pulses on external triggering, modulating the repetition frequency, and more. However, these generators are expensive.

If you need a current- or voltage pulse of predetermined amplitude and width, with the fundamental requirement that its rise- or fall time is below a nanosecond, then the simple circuit shown in Figure 1 can do this easily and cheaply.