A model for integrated spiral inductors which incorporates the physically expected frequency-dependent effects modifying the device's impedance is proposed. Moreover, it is demonstrated that the effect of resonances occurring outside the bandwidth of applicability for the device may considerably influence the performance around the peak of the Q-factor versus frequency curve. In this paper, we present the use of cascaded resonant circuits to represent the additional resonances occurring in the device to improve model accuracy up to 60 GHz.