VHDL-AMS modeling of DC-DC converters for steady-state analysis

The paper describes a technique for creating behavioral models of switched DC-DC converters based on a combination of the averaged and the switch-level modeling styles, which allows performing steady-state analysis using a single run of the standard Spice transient simulation. The averaging consists in creating an equivalent model of DC-DC converter for quantities averaged over the switching period. Finding the DC operating point of an averaged model is equivalent to finding the steady-state solution in the switch-level model. Standard transient simulation with the DC operating point as the initial condition is then equivalent to the steady-state analysis. The technique of modified PWM switch is used, which allows incorporating the on-resistance of the active switch together with the forward voltage drop and the differential resistance of diode-type passive switch. This approach allows sharing the values of state variables between DC and transient analyses.