Development of memristor device models is a research topic of utmost interest. As the resistance switching mechanism is not always known in all details, several “behavioral” models employ window functions (WFs) to improve accuracy and to capture the switching-rate dependency on the bias conditions. The WFs published so far are functions of just the state variable(s), whose effectiveness was tested in fitting typical hysteretic i-v characteristics, ignoring the effect of the applied signal magnitude in dynamic behavior. In this context, we introduce a generalized concept of bias-dependent WFs, designed to enhance simple behavioral models by making possible capturing rich dynamic time-response of memristors. An implementation example is presented and its effect on the response of a threshold-based model of a voltage-controlled bipolar memristor was evaluated in simulations with LTSPICE.