Compact Solid-State Marx Modulator With Fast Switching for Nanosecond Pulse

This article describes the compact solid-state Marx modulator (SSMM) with a fast rising time and a short pulsewidth based on the modular structure. By stacking of the TO-263-7 packaged silicon carbide
mosfet
s having high voltage and fast switching capabilities, the designed circuit consists of three components, including the Marx capacitor, an
on
switch for applying pulse to the load, and an
off
switch to pull down the pulse. The
off
switch connected in parallel with load is chosen as a
mosfet
instead of a diode that is used in the conventional Marx generator. Because the
off
switch provides a discharging path for the stored energy on the parasitic capacitance, it is highly related to the fast falling time. In order to provide complementary driving signal and power for
on/off
switches, the simple control algorithm with a minimum component count and a reliable drive circuit against the noise are proposed. In addition, the synchronization of all the gate signals and a compact configuration for minimizing the stray inductance are essential to shorten the rising, falling, and pulsewidth. Based on the proposed circuit, the following specifications of the developed SSMM are achieved: the output voltage of 10 kV, the pulsewidth of less than 50 ns, and the rising and falling times of less than 15 ns.