Parasitic Inductance
====================

Parasitic inductance checks identify wirebond, via, loop, and package effects that
                shift mode frequencies and add crosstalk.

.. list-table::
   :header-rows: 1

   * - #
     - Parameter
     - Symbol / Unit
     - Extraction Method
     - Typical Q3D Value
     - Ideal / Optimal
     - Good Range
     - Worst Case
     - Why It Matters
     - Key Design Note
   * - 25
     - Wirebond / Bump Inductance
     - L_wb / nH
     - Q3D wire cylinder model; HFSS S-parameter fitting
     - 0.5 – 2 nH per bond
     - < 1 nH
     - 0.3 – 3 nH
     - > 5 nH
     - Series inductance in signal path creates impedance discontinuity; resonates
                        near operating freq
     - Flip-chip indium bumps reduce L_wb to ~0.1 nH vs 1–2 nH for wirebonds; key
                        for 3D scaling
   * - 26
     - Control Line Lead Inductance
     - L_lead / pH
     - Q3D PEEC; partial inductance extraction
     - < 100 pH
     - < 100 pH (short on-chip)
     - 50 – 500 pH
     - > 2 nH
     - Lead inductance in flux/charge bias lines causes AC flux errors and qubit
                        frequency shifts
     - Long coax from room-temperature electronics adds 1–10 nH; de-embed by
                        careful calibration
   * - 27
     - Ground Plane Slot Inductance
     - L_slot / pH/sq
     - Q3D mesh simulation of ground plane geometry
     - < 1 pH/sq
     - < 1 pH/sq (continuous ground)
     - 1 – 5 pH/sq
     - > 20 pH/sq
     - Inductance from ground return path gaps distorts mode frequencies across the
                        chip
     - Vortex-pinning holes (diameter ~ 1 μm, pitch ~ 2 μm) add ~5–10 pH/sq but are
                        necessary at B > 0
   * - 28
     - Package / Board Parasitic Inductance
     - L_pkg / nH
     - HFSS full package model + Q3D trace extraction
     - < 0.5 nH (SMA launch)
     - < 0.5 nH
     - 0.5 – 2 nH
     - > 5 nH
     - Package inductance shifts resonator input impedance; must be de-embedded
                        from measurement
     - Surface-mount SMP connectors (< 0.3 nH) preferred over SMA (~0.5–1 nH)
                        for cryo packages