Wound vs Thin-Film Inductor Comparison
| Property | Wound (LQG/LQM) | Thin-Film (LQP) |
|---|---|---|
| Construction | Wire wound on ferrite core | Spiral conductor on ceramic |
| DC resistance | Lower (thick wire) | Higher (thin film conductor) |
| SRF | Lower (more turns = more Cp) | Higher (fewer turns, less Cp) |
| Q at 1 GHz | 20–50 | 40–80 |
| Best frequency | <1 GHz (DC/switching) | 0.5–5 GHz (RF matching) |
| Typical series | Murata LQG/LQM | Murata LQP15MN |
Analyzing Wound vs Thin-Film at 900 MHz
Load two .s2p files in RF View simultaneously: LQG18HN100J00 (wound 10nH): Q ≈ 35 at 900 MHz LQP15MN100G8ZD (thin-film 10nH): Q ≈ 55 at 900 MHz S11 Smith chart overlay: Both traces should be in upper (inductive) half at 900 MHz LQP15 trace stays on inductive arc further (higher Q = lower ESR) LQG18 trace deviates more from pure inductive arc (lower Q = higher ESR) At self-resonant frequency: LQP15 SRF ≈ 5 GHz (trace crosses real axis at SRF) LQG18 SRF ≈ 2 GHz (lower SRF due to more parasitic capacitance)
Choosing the Right Inductor
- Above 1 GHz, <100 nH: Use thin-film (LQP series) — higher Q, higher SRF
- Below 500 MHz, current choke: Wound (LQG/LQM) — lower DCR for bias feeds
- RF bypass/choke at >2 GHz: Wire-wound ferrite bead with high impedance
- Critical matching >2.4 GHz: 0201 thin-film for higher SRF and smaller size
RF View Inductor Comparison: Load wound and thin-film .s2p files simultaneously. Smith chart overlay immediately shows SRF difference and Q comparison. Choose the better type for your frequency. Free on Android.