Why Substitution Is Critical
Auto Match synthesis gives ideal L/C values (e.g., L=3.54 nH, C=6.82 pF) that don't account for real-world component limitations: finite Q (loss), self-resonant frequency (SRF) where component behavior inverts, and package parasitic inductance. Substituting real components before PCB assembly prevents surprises.
Manual Substitution Workflow
- Identify nearest standard values: 3.54 nH → pick 3.3 nH or 3.9 nH (E12 series)
- Download manufacturer .s2p: Murata SimSurfing → LQP15MN3N3 (3.3 nH) .s2p
- Load in Circuit Simulator as S2P block (instead of ideal L element)
- Re-simulate: Compare real vs ideal S11 performance
- Iterate: Try 3.9 nH if 3.3 nH gives better performance
RF View Real Match (Automated)
After Auto Match in RF View:
1. Tap "Real Match" button
2. RF View searches Murata catalog:
→ Finds nearest L value in LQP15MN or LQP03TN series
→ Finds nearest C value in GRM0335 or GJM0335 C0G series
3. Loads measured .s2p for each selected component
4. Re-runs circuit simulation with real component data
5. Displays matched S11 with real components
The real component simulation includes:
- Finite Q factor (ESR loss)
- Self-resonant frequency (SRF) behavior
- Package parasitic capacitance
- Inter-lead inductance
Comparing Ideal vs Real Performance
Common observations after Real Match: 1. S11 dip shifts in frequency slightly (component value ≠ ideal) 2. S11 depth decreases (finite Q adds insertion loss) 3. New resonance appears above design freq (SRF effect) If S11 depth drops below −10 dB: try adjacent E12 value If frequency shift: both L and C shifts should be opposite → sometimes cancel If new resonance appears: choose component with higher SRF (smaller package)
RF View Real Match: One-tap replacement of ideal L/C values with Murata catalog components including measured S-parameter data. Shows realistic performance before PCB assembly. Free on Android.