Internal Microwave Propagation and Distortion Characteristics of Travelling-Wave Amplifiers Studied by Electro-Optic Sampling

The internal signal propagation and saturation characteristics of two monolithic microwave travelling-wave amplifiers (TWA) are measured by electro-optic sampling. Gate and drainline responses are compared with theory and simulation, leading to revisions in the FET models. Drain voltage frequency dependence and harmonic current propagation together lead to more complex saturation behavior than is discussed in the literature.