Why do the pi commands generate multiple Q values?
Q1 represents the Q of the 2-port if you were to ground the inner port of the spiral. Similarly, Q2 represents the Q looking in from the inner port and grounding the outer port. Usually Q1 > Q2 since Q2 has extra substrate losses associated with the bottom metal layer. For symmetric inductors Q1 ~ Q2. Q3 or Qd represents the differential Q if you were to drive the structure differentially. Qd > max(Q1,Q2) since the substrate injection is minimized. Note that the concept of the outer and inner port of the spiral depends on the order of the spiral segments (see PSEGS to display the segments).
