Anjan Chakravorty

The on-chip planar spiral inductors having variable width (W) and spacing (S) across their turns are known to exhibit higher quality factors (Q). In this paper, we present an efficient parameterized cell (pcell) design in cadence using SKILL scripts for automatic layout generation of these complex, high-Q, variable W&S spiral inductors comprising of single ended and symmetric structures with rectangular, hexagonal, octagonal and circular spirals. Electromagnetic simulations are performed on the inductor layouts generated using the developed pcells. The constant W&S and variable W&S spiral inductor structures are fabricated in a 0.18 μm silicon on insulator process. Measurements show ∼25% improvement in the quality factor of variable W%S spiral inductors compared to their constant W&S counterparts and also validates the proper operation of the developed inductor parameterized cells. The presented variable W&S inductor pcell significantly reduces the layout design time of RF circuit designers and also helps in the design automation of these complex inductor structures to boost their own performance and the RF circuits as well.

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 $0.18~\mu \text{m}$ 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.