Quasi-Static Derived Physically Expressive Circuit Model for Lossy Integrated RF Passives

This paper presents a novel approach for deriving a physically meaningful circuit model for integrated RF lossy passives such as spiral inductors on a silicon substrate. The approach starts from a quasi-static partial element equivalent circuit (PEEC) model. The concept of complex inductance and capacitance is introduced to uniformly deal with the conductor and dielectric losses. Basic Y- Delta network transformation is used to ldquoabsorbrdquo the insignificant internal nodes of the original PEEC network and to reduce the order of the circuit model. The physically expressive circuit model given here can be very concise while preserving the major physical meanings and attributes of the original circuit layout. A low-temperature co-fired ceramic bandpass filter and two practical inductors fabricated using a 0.18-mum CMOS process are studied by the model to demonstrate the validity of this new approach. Furthermore, the stability condition of the model is also discussed.