A new stratified crossed stacked spiral inductor with improved self-resonance frequency

A new stratified crossed structure to decrease the parasitic capacitance of stacked spiral inductor is proposed. By shifting the neighbor trace at same layer to the adjacent, the capacitances between the inductor´s strips are effectively compressed. Hence, its self-resonance frequency and quality factor can be improved. In order to evaluate the performance of the proposed inductor, both the conventional and the proposed stacked spiral inductors have been simulated and compared by Ansoft^™ HFSS. The results show that the self-resonant frequency (f_SR) and maximum quality factor (Q) of the proposed 3.4-nH inductor have 87% and 15% improvements, respectively, compared with those of the conventional inductor. Meanwhile, the presented stratified crossed structure can be integrated into RF circuits based on conventional CMOS process. All analysis and results are valuable for optimizing on-chip stacked spiral inductors, especially for their application on high frequency circuits.