Modeling of High-Q Conical Inductors and MOM Capacitors for Millimeter- Wave Applications

Conical inductors and metal-oxide-metal (MOM) capacitors are shown to have higher quality factor (Q) characteristics at millimeter wave (mm-wave) frequencies over conventional inductors and nitride MIM capacitors. In this work, Physics-based analytical models are developed for conical inductors and MOM capacitors usable at mm-wave frequencies. The linear voltage profile along the turns of the conical inductor is taken into account for capacitance calculation which is critical in accurately predicting Q-values. Two RL networks coupled by capacitors are proposed to capture the frequency-dependent characteristics of the MOM capacitor. The lumped elements in both these device models are frequency independent and can be calculated using layout and process parameters. The proposed models for conical inductors and MOM capacitors are verified with electromagnetic (EM) simulations till 100 GHz. A prototype 60-GHz bandpass filter (BPF) is fabricated using 0.18 mu m RF-silicon on insulator (SOI) technology to validate the accuracy of the developed compact models. BPF simulation results using the proposed models are shown to be in excellent agreement with those produced with EM simulations and silicon measurements.