Pulse generators based upon avalanche transistors offer fast risetimes, high voltages but low average power, and fairly short pulselengths. Applications include the driving of pockels cells and other electro-optic devices, ultrawideband radar, cable testing and characterisation, sweep and ramp generators, time of flight mass spectroscopy and numerous other applications.

A single avalanche transistor is capable of very limited performance. Our pulsers achieve their high performance by the coupling together of many (thousands in the case of large systems) devices in such a way that the power from each device appears at the output synchronously.

An avalanche effect whether it is in a transistor or some other kind of discharge is a very nonlinear, high gain phenomenum. The non linearity results in the very fast risetimes achieveable, whilst the high gain results in some system jitter. Kentech employs special techniques to keep the jitter at a minimum and as a result is able to offer multichannel pulse systems in which the channel to channel jitter is barely measurable whilst the overal input to output jitter may be up to 20ps peak to peak.

Avalanche pulsers come in two distict types, formed pulse devices and raw pulsers. Typical waveforms from our CPS series are shown below:-

In many cases it is possible to use an unformed pulse and this offers much better use of pulser power. Shaping the pulse often makes the rising edge slower. The falling edge is usually slower than the rising edge, especially on long pulse lengths. When a shaped pulse is required then there are several options that need to be considered. In particular:-

For resistive loads, the pulsers generally drive into 50Ωbut other impedances can be driven via transformers or multichannel outputs.
For capacitive loads the risetime may be set by the source impedance, so this should be selected suitably.