Contactless Terahertz Sensing of Ultrafast Switching in Marx Generator Based on Avalanche Transistors

In this letter, we have studied the temporal evolution of switching for each stage of the Marx generator with picosecond temporal and millimeter spatial resolutions employing terahertz measurements. The Marx circuit utilizes collapsing-field-domain (CFD)-based avalanche switches, which are formed in a bipolar GaAs structure and result in the picosecond speed of powerful carrier generation and electrical switching. The application of the CFD-based avalanche switches emitting mm-wave pulsed radiation in the Marx generator provides a unique opportunity to accurately track the switching instants for each of the circuit stages with a picosecond time precision. The collapsing domains cause the sub-THz pulses radiated by each of the avalanche switches, and the same domains generate the electron-hole plasma thus causing simultaneously the electrical switching. In this work, we report the direct measurements of the switching instants for each of the four stages Marx generator and suggest an interpretation of non-trivial experimental results.