What Is an RF Inductor?
An RF inductor is an inductor designed to work with low loss at high frequencies (MHz–GHz). It's a core part of radio, antenna and communication circuits.
Difference From a Power Inductor
A power inductor is for high current and energy storage; an RF inductor is optimized for low loss and stable inductance at high frequency. It's usually small-valued (nH–µH) and carries low current.
Q Factor (Quality)
It's the RF inductor's most important metric: the ratio of stored energy to loss. A high Q means sharper resonance and less loss; it directly affects filter and oscillator performance.
Self-Resonant Frequency (SRF)
Every coil has a parasitic capacitance between its turns. At a certain frequency the coil resonates with its own capacitance (SRF) and above that no longer behaves like an inductor. An RF inductor should not be chosen with an SRF far below the operating frequency.
| Parameter | Meaning |
|---|---|
| Inductance (nH) | Usually a small value |
| Q factor | High = low loss |
| SRF | Upper operating limit |
Where Is It Used?
RF filters, matching circuits, oscillators, antenna circuits and wireless communication modules.
Common Mistakes
- Ignoring the SRF: if the operating frequency is near the SRF, the coil doesn't behave as expected.
- Choosing a low Q: loss rises in the filter and selectivity drops.
- Layout: at RF, PCB layout and orientation affect the inductance.
Frequently Asked Questions
Why does the Q factor matter?+
Can a power inductor be used instead of an RF inductor?+
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