// S-Parameters › Signal Integrity
Group Delay, TDR & Signal Integrity
Upload a 2-port S-parameter file to analyse group delay, simulate TDR/TDT, and run passivity and causality checks — all in the browser.
// How to use
1
Upload a .s2p Touchstone file — MA, RI and DB formats supported. Exported from VNA, ADS, HFSS, or any RF simulator.
2
Group Delay is −dφ/dω from the unwrapped phase. Adjust smoothing window to reduce numerical noise at phase transitions.
3
TDR IFFTs S11 → time domain. Shows impedance discontinuities. Set velocity factor Vf to convert time → distance. TDT does the same for S21 (forward path).
4
Passivity checks σ_max(S) ≤ 1 at every frequency. Violations mean the device appears to have gain — could be a measurement artifact.
5
Causality checks for pre-response energy before t = 0. Pre-causal energy > 1% = Marginal · > 5% = Fail.
// S-Parameter File
Drop .s2p here
or click to browse
or click to browse
// Group Delay Options
1 = no smoothing
// TDR / TDT Options
× c (0.66 = FR4)
Ω
Show TDT (S21 time-domain transmission)
// Key Formulas
Group Delay:τ(ω) = −dφ/dω = −dφ/(2π·df)
TDR Impedance:
Z(t) = Z₀·(1+Γ(t))/(1−Γ(t))
Passivity:
σ_max[S] ≤ 1 ∀ω ⟺ no port gain
Causality:
h(t) = IFFT{S₂₁(f)} = 0 for t<0
Pre-causal % = E(t<0)/E_total × 100
Upload a .s2p file to begin.
Group Delay · TDR/TDT · Passivity · Causality
Group Delay · TDR/TDT · Passivity · Causality