On-chip vertical tapered solenoid inductor with high self-resonance frequency

A novel on-chip vertical tapered solenoid inductor has been designed, fabricated and experimentally characterised. Owing to its vertical tapered solenoid structure, it is observed that the frequency corresponding to the peak quality factor (f(Qmax)) increases by 160%, i.e. from 4.05 to 10.55 GHz, and the self-resonance frequency (f(sr)) increases from 21.3 to more than 25 GHz, when compared to a traditional planar inductor of similar inductance and on-chip area. Further, this inductor is found to exhibit a self-shielding characteristic which has a strong impact on the requirements of floating shields underneath the inductor. The performance of the inductor is also characterised at different temperatures.