Modelling of On-chip Spiral Inductors for Silicon RFICs

Download or read book Modelling of On-chip Spiral Inductors for Silicon RFICs written by Daniel Melendy and published by . This book was released on 2002 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: In high-frequency circuit design, performance is often limited by the quality of the passive components available for a particular process. Specifically, spiral inductors can be a major bottle-neck for Voltage-Controlled Oscillators (VCOs), Low-Noise Amplifiers (LNAs), mixers, etc. For designers to correctly optimize a circuit using a spiral inductor, several frequency-domain characteristics must be known including the quality factor (Q), total inductance, and the self-resonant frequency. This information can be difficult to predict for spirals built on lossy silicon substrates because of the complicated frequency-dependent loss mechanisms present. The first part of this research addresses the need for a scalable, predictive model for obtaining the frequency domain behavior of spiral inductors on lossy silicon substrates. The technique is based on the Partial Element Equivalent Circuit (PEEC) method and is a flexible approach to modelling spiral inductors. The basic PEEC technique is also enhanced to efficiently include the frequency dependent eddy-currents in the lossy substrate through a new complex-image method. This enhanced PEEC approach includes all of the major non-ideal effects including the conductor-skin and proximity effects, as well as the substrate-skin effect. The approach is applied to octagonal spiral inductors and comparisons with measurements are presented. To complement the scalable enhanced-PEEC model, a new wide-band compact equivalent circuit model is presented which is suitable for time-domain simulations. This model achieves wide-band accuracy through the use of "transformer-loops" to model losses caused by the magnetic field. A fast extraction technique based on a least squares fitting procedure is also described. Results are presented for a transformer-loop compact model extracted from measurements. The combination of an accurate scalable model and a wide-band compact equivalent-circuit model provides a complete modelling methodology for spiral inductors on lossy silicon.