Quality factor¶
Quality factor (Q) computation for an inductor.
Q is the ratio of imaginary to real part of the input impedance:
\[Q = \frac{\omega L}{R(\omega)}\]
For a planar inductor on a lossy substrate the full Q-factor includes
substrate-loss contributions; this initial implementation gives the
metal-loss-only Q, which is the upper bound and the value the binary
prints as Q_metal for spirals far below their self-resonance.