LFT representations of parametrized polynomial systems

The paper focuses on general linear constant differential systems in which the coefficients depend polynomially on several parameters. It is shown how the system matrix can be written in terms of a linear fractional transformation (LFT), which is a representation that extracts the parametric uncertainty. The LFT form yields lower bounds for the robust stability radius of the system via /spl mu/-analysis tools. The method is applied to the linearized model of a transistor amplifier.