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

This paper formulates various quality (Q) factors associated with the applications of on-chip spiral inductors to radio-frequency integrated circuits using S-parameters. The formulations start with the Q factor of a spiral inductor in a generalized two-port configuration based on a new complex-power approach and then extend to the Q factors of a tank and matching circuits that use the spiral inductors. In the demonstration, the two-port S-parameters for a series of CMOS spiral inductors have been measured to further generate such various Q factors for a many-sided evaluation of the inductor performance.