Bond Wire & Via Inductance Calculator

Bond wires and PCB vias are unavoidable parasitics in RF circuits. Their inductance causes impedance transformation, resonances, and gain roll-off. At GHz frequencies even a short bond wire has significant reactance. Use this tool to estimate the parasitic inductance before committing to a layout.

Equations & Parameters ▸

\(L_{wire}=0.2\ell\!\left[\ln\!\left(\tfrac{2\ell}{d}\right)-0.75\right]\text{nH},\quad L_{via}=0.2h\ln\!\left(\tfrac{4h}{d}\right)\text{nH},\quad C_{via}=\tfrac{1.41\varepsilon_r h}{\ln(D/d)}\text{pF}\)

Bond wire	Gold or aluminium wire connecting die to package. Inductance ≈ 1 nH/mm; exact value depends on height, loop shape, and proximity to other conductors.
PCB via	Plated-through hole connecting layers. Inductance depends on height and diameter; has associated parasitic capacitance from the antipad.
Grover formula	L_wire = 0.2·ℓ·[ln(2ℓ/d) − 0.75] nH, ℓ and d in mm.
Via formula	L_via ≈ 0.2·h·ln(4h/d) nH, C_via ≈ 1.41·εᵣ·h/ln(D/d) pF.

Physical constants used

c	Speed of light = 2.998×10⁸ m/s
µ₀	Permeability of free space = 4π×10⁻⁷ H/m
σ_Cu	Copper conductivity = 5.8×10⁷ S/m
σ_Al	Aluminium conductivity = 3.8×10⁷ S/m
σ_Ag	Silver conductivity = 6.3×10⁷ S/m

Bond Wire

Wire length, ℓ

centre-to-centre arc length

Wire diameter, d

gold: 0.018–0.033 mm, Al: 0.025–0.125 mm

Wire height, h

loop height above bond pads

Bond Wire

Inductance, L_wire—

Reactance at 1 GHz—

Reactance at 10 GHz—

PCB Via

Via height, h

substrate thickness

Via diameter, d

drill diameter

Antipad diameter, D

clearance hole in ground plane

Substrate εᵣ, εᵣ

FR4≈4.4

Via Parasitics

Inductance, L_via—

Capacitance, C_via—

Self-resonant frequency—

Diagram

📖 Learn the theory behind this tool →