Model Analysis And Optimization Design Of RF On-chip Spiral Inductor

Recently, silicon-based on-chip spiral inductor which can be widely used in wireless telecommunication has received more and more international attention as it is a key element to realize monolithic silicon-radio frequency integrated circuit (Si-RFIC). There are many aspects to research on-chip inductor and the research in this paper is on the computation of inductance, the improvement of physical model and optimization of quality factor (Q) of inductor.Based on Greenhouse algorithm and Jenei algorithm, we compute the inductance of the novel inductor by physics -based approximation algorithm which calculates the inductance by summing every turn of the inductor. The algorithm is efficient and scalable and also provides good accuracy for conventional inductor with errors of about 6.5 %. A research on wide-band on-chip spiral inductors modeling is also performed in the thesis. By introducing distributed effects and the asymmetry effects in amendment model, the discrepancies between the conventional inductor model and the simulated data at high frequencies are greatly improved. The amendment models of inductors are then verified by the quasi-3D EM software.After analyzing in detail the energy loss mechanism of the inductor by electromagnetic theory, we propose a novel inductor layout structure with gradually reduced metal line width and space from outside to inside. The optimized inductors have shown less eddy-current losses than the conventional designs whose metal line width and space are normally fixed. Based on these kinds of advanced inductors, series resistance Rs could be reduced and at the same time, the quality factor of the inductor (Q) would be increased. In the experiments, monolithic on-chip inductors are successfully fabricated on silicon with high resistivity in CMOS process. The obtained results have corroborated the validity of the proposed method. Measurement results indicate Q factor of a 5.96-nH new designed inductor on high-resistance silicon at 2.4 GHz is 14.23, 11.6% higher than the conventional structure with the same layout size.In conclusion, all the experiment results show that the optimized inductors are reasonable and IC designers will benefit from them.