Modeling of Current-Return-Path Effect on Single-Ended Inductor in Millimeter-Wave Regime

The effect of current return path (CRP) on the accurate modeling of single-ended inductors in the millimeter-wave regime has been investigated. A series of spiral inductors with different sizes, shapes, and CRP positions was fabricated in a 0.18-μm RF-CMOS process and measured up to 50 GHz. An analytical appended model for CRP is developed to characterize the effect, and its equivalent circuit is validated by measurement results. The proposed model can help millimeter-wave circuit designers to devise layout routing flexibly with high accuracy.