Series Stacked Multipath Inductor With High Self Resonant Frequency

In this brief, a novel combination of multilayer up-down series stacking and multipath architecture for equal path length is explored for the first time to improve the performance of on-chip inductors. The up-down series winding reduces the interlayer capacitance, thereby increasing both the peak quality-factor (Q) frequency ( f_Qmax) and self resonant frequency (SRF). The crossover interconnection architecture ensures equal path length at every pair of spiral turns in the series stack. This architecture lowers skin and proximity effect losses in the spiral, increasing the slope of Q characteristics. Thus, using the proposed architecture, both the ac resistance and capacitance are simultaneously reduced while realizing higher inductance values. Implemented in a 0.18 μm high resistivity silicon-on-insulator technology using a dual thick metal stack, the proposed inductor achieves more than 10% improvement in peak-Q value, 50% improvement in f_Qmax, and 100% improvement in SRF values when compared with a conventional series stacked multipath inductor.