From Frequency-Domain Physics-Based Simulation to Time-Domain Modeling of Traveling-Wave Tube Amplifiers for High Data-Rate Communication Applications

We report here on a methodology to use frequency-domain physics-based nonlinear simulations of traveling-wave tubes (TWTs) in block time-domain models. We present examples using an improved version of the large-signal code CHRISTINE and a two-block baseband time-dependent model with a feedback loop that takes into account reflections internal to the TWT. The novelty in this approach is that it enables us to relate digital performance to the physical characteristics of the device, and it has the potential to significantly impact the analysis of TWT amplifiers for high data-rate applications.