Authors: A.S. Peng, K.M. Chen, G.W. Huang, S.C. Wang, H.Y. Chen and C.Y. Chang
Affilation: National Nano Device Laboratories, Taiwan
Pages: 155 - 158
Keywords: tapered inductor, quality factor, skin effect, frequency-dependent resistance
The characteristics of tapered inductors and standard inductors have been compared, and an improved compact model for tapered inductors is presented. The measured data of spiral inductors shows that the tapered inductor has higher quality factor (Q) than standard ones above 2.3GHz and higher frequency in which the maximum Q occurs. Because the parasitic capacitances, such as parallel capacitance and oxide capacitance, have lower values for tapered inductors, the real part of the input impedance is smaller, leading to higher Q value. For accurately modeling the behavior of tapered inductors, we propose an improved compact model, which adds a branch to model the frequency-dependent resistance. This model has the advantage of easily acquiring a relative equation because of the simple parallel structure of the skin effect model. The modeled and measured results have excellent agreement.