S-parameter formulation of quality factor for a spiral inductor in generalized two-port configuration

In this paper, we present the most rigorous S-parameter formulation of quality (Q) factor that has ever been seen for a spiral inductor in generalized two-port configuration. The derivation employs a complex power concept and can reduce to the conventional Q-factor expression based on one-port inductor model with the second port grounded. The Q factor of a tank circuit that connects the spiral inductor with an ideally lossless capacitor in series or in parallel can be also predicted successfully using this Q-parameter formulation.