A modified double-π equivalent circuit model for silicon-based planar spiral inductors and its application to a RF mixer

At high frequencies, the traditional single-π equivalent-circuit model can´t accurately describe the electrical performance of silicon-based planar spiral inductors. In this paper, a modified wide-band, scalable double-π equivalent-circuit model is presented with consideration of skin effect, proximity effect, substrate effect, feed-through capacitance, line coupling capacitance. The modeling methodology is applied to various sizes silicon-based planar spiral inductors, and the extracted model shows excellent agreement with the data simulated with the electromagnetic field solver (ADS momentum) over a frequency range of 0.1 to 10GHz. Finally, the scalable double-π equivalent-circuit model is applied in a 0.25μm CMOS wide-band mixer design, which shows the flexibility of the simplified model in AC and transient analysis.