Wireless LAN (WLAN) operating in the 5-6 GHz range, become commercially viable only, if they can be produced at low cost. Consequently, tight integration of the physical layer, consisting of the radio front-end and the digital signal processing part, is a must. Especially with respect to mixed-signal feedback loops, with automatic gain control as a recurring example, existing tools have major difficulties in offering efficient ways of modeling and simulation. We present a modeling approach where the complexity of the analog behavioral model has been reduced to the minimum required by the digital receiver, namely its steady-state responses and a ?worst-case? time delay. Moreover, we show how this mixed-signal receiver model can be used in an end-to-end communication link simulation to provide the designer insight into statistical information such as transient delays and gain tolerances. For this model, we set up a co-simulation of two existing in-house tools, one for the analog part, the other for the digital system part.