  We have developed an avalanche transistor-based pulse generator for driving
the photocathode of an image intensifier, which comprises a mainly capacitive
load on the order of 100 pF. The circuit produces flat-top pulses with rise
time of 2 ns, FWHM of 10 ns and amplitude of tens of V at a high repetition
rate in the range of tens of MHz. The generator is built of identical avalanche
transistor sections connected in parallel and triggered in a sequence,
synchronized to a reference rf signal. The described circuit and mode of
operation overcome the power dissipation limit of avalanche transistor
generators and enable a significant increase of pulse repetition rates. Our
approach is naturally suited for synchronized imaging applications at low light
levels.
