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Planar Spiral Inductor Calculator
Estimate PCB planar spiral inductance, copper resistance, Q factor, inner dimension, and trace length from spiral geometry.
Input Parameters
Results
For RF spirals, treat Q and high-frequency behavior as approximate.
Equations Used
Inductance Model:
Uses the modified Wheeler/Mohan-style planar spiral approximation.
Fill Ratio:
ρ = (Dout - Din) / (Dout + Din)
Copper Resistance:
R = ρCu × length / area
Q Factor:
Q ≈ 2πfL / R for a simplified copper-loss estimate.
Frequently Asked Questions (FAQ)
Q1: What does this spiral inductor calculator estimate?
It estimates inductance, copper resistance, Q factor, inner dimension, and approximate trace length for a PCB planar spiral.
Q2: Is this accurate for RF IC or microwave spiral inductors?
It is a first-pass estimate. RF inductors require EM simulation because substrate loss, parasitic capacitance, and metal thickness matter.
Q3: Why does spacing affect inductance?
Spacing changes the average diameter and magnetic coupling between turns.
Q4: Why is Q only approximate?
The Q estimate uses simple copper resistance and does not include skin effect, proximity effect, substrate loss, or parasitic capacitance.
Q5: When should I use EM simulation?
Use EM simulation for RF, high-Q, high-frequency, or production-critical spiral inductors.
Q6: Can this be used for PCB power inductors?
No. It is for planar spiral geometry, not wound power inductors with magnetic cores.
