Lumped Modeling of Differentially Driven Symmetric Inductors for RF IC Design

This paper presents a lumped scalable model of integrated inductors for RF IC design. The model is validated up to 20 GHz by comparison with on-wafer measurements of both single-ended and differentially driven spirals covering 0.2- to 8.3-nH inductance values. Average errors on inductance, self-resonance frequency and quality factor are 2%, 5%, and 7%, respectively. High accuracy, full geometrical scalability and compactness promote the proposed model as a reliable time-saving design tool. As an example of model exploitation, an image-reject down-converter for 5-GHz wireless local area networks is presented. In this circuit differentially driven symmetric inductors are adopted to implement monolithic filters, which provide an image-rejection ratio as high as 56 dB