Oscillating Pulse Generator Based on a Nonlinear Inductive Line

Abstract

A chain of cascading LC sections consisting of series nonlinear inductors and parallel linear capacitors can be used to generate oscillating pulses. When a rectangular pulse is injected into the input of such a nonlinear inductive line (NLIL), the pulse undergoes modulation and exits at the output with oscillations in the waveform. This paper describes the implementation of high-voltage NLILs using commercial-off-the-shelf components. A pulser comprising of a storage capacitor and a fast semiconductor switch is used to provide the input pulse with approximate rectangular pulse shape. The design of the NLIL, which is a type of nonlinear lumped element transmission line (NLETL), is based on a NLETL circuit model developed earlier in-house. The nonlinear inductors made of ferrites are modeled using a simplified form of the Landau-Lifshitz-Gilbert (LLG) equation. A simple novel approach is proposed to determine the characteristic parameters in the LLG equation. Simulation results from the NLETL model are compared to the experimental results, and analyses on the voltage modulation and frequency content of the output pulses are performed. The use of crosslink capacitors in the line to modify the dispersive characteristics to enhance the performance is also investigated. With the results, the conditions and trends for producing oscillating pulses in NLILs are discussed.