Novel Tunable Ultrashort Pulse Generator With High Amplitude and Low Ringing Level

A new design of the ultrashort pulse generator based on a step recovery diode (SRD) is presented in this letter. The design schematic features allow us to increase the pulse amplitude, decrease the ringing level, and realize pulse duration tuning. The signal amplitude increase results from the use of an additional inductive energy storage, which accumulates energy of the magnetic field during both charge storing and extraction phases of the generator duty cycle. The ringing level is reduced by including the ringing reduction subcircuit in the design. This subcircuit consists of the Schottky diode to block the negative half-waves of ringing oscillation and the resistor to force oscillation fading. The electronic tuning of the pulse duration is based on the relation between the SRD recovery time and the forward current. In the experiments ultrashort pulses with the duration in a range from 350 psto 1.5 ns and the 40-V amplitude were obtained for a 50-Ω load by varying the diode forward current. The output signal has a good symmetry shape, which is shown both in simulation and experimentally. The measured ringing level was -20.5 dB.