Baseband Modeling Using Multidimensional Networks in VHDL-AMS

Baseband models are widely used to describe the behavior of RF systems. They suppress the RF carrier. Thus, they are many times faster than passband models that evaluate every carrier cycle during the simulation. Nevertheless, passband models are necessary for the component design. To support the top-down design approach, consistent models at baseband and passband level are required. The paper shows how the consistency can be achieved using consequently the possibilities of overloading functions and operators in VHDL-AMS. The mathematical basis is a consistent usage of the describing function theory for baseband modeling. The classical approach of baseband modeling can be extended by completing the waveforms that carry the in-phase and quadrature component by a time-discrete or time-continuous waveform that saves the carrier frequency information. This allows to handle systems with different carriers in different parts of a system or to sweep the carrier frequency during the simulation. Keywords VHDL-AMS, baseband modeling, describing function