This paper introduces an approach to model the power consumption of analog and mixed-signal systems at system level. The method is based on power state machines and is practically applied to a zero-IF receiver. The power state machines model the static power consumption of components with respect to their current state or state transition. The power consumption per state and state transition, respectively, is obtained from a low-level circuit simulation or from measurement. The concept of power state machines can be used for any analog component and enables the simulation of heterogeneous systems with the benefit of a fast simulation time.