Interactive labs to explore PDN impedance, decoupling strategies, anti-resonance, IR drop, ground bounce, and plane resonance. Adjust parameters and observe real-time results.
Lab 1: PDN Impedance Analysis
Visualize the power delivery network impedance across frequency. The goal is to keep impedance below the target impedance line (Ztarget = Vripple / Iload) across all frequencies of interest.
Adjust controls and observe the PDN impedance profile. The red dashed line is your target impedance.
Lab 2: Decoupling Capacitor Optimization
See how individual capacitors contribute to the combined PDN impedance. Each capacitor has its own resonance; combining them fills the frequency gaps.
100 μF
50 mΩ
5.0 nH
10 μF
10 mΩ
1.0 nH
100 nF
5 mΩ
0.5 nH
Blue = Cap A (bulk), Green = Cap B (MLCC), Magenta = Cap C (HF), White = Combined
Lab 3: Anti-Resonance Exploration
When two capacitors are connected in parallel, anti-resonance can create an impedance peak between their individual self-resonant frequencies. This lab lets you see how values affect the peak magnitude.
Anti-resonance occurs between fSRF1 and fSRF2 where the inductive impedance of one cap equals the capacitive impedance of the other.
100 μF
50 mΩ
5.0 nH
100 nF
5 mΩ
0.5 nH
Tip: Increase Cap 1's ESR to dampen the anti-resonance peak. Adding a third intermediate cap also helps bridge the gap.
Blue = Cap 1, Orange = Cap 2, Yellow = Combined (watch for anti-resonance peak!)
Lab 4: IR Drop Analysis
Calculate and visualize voltage drop across a power plane. Thicker copper and wider planes reduce resistance, lowering IR drop.
R = ρ × L / (W × t) | Vdrop = I × R |
ρCu = 1.68 × 10-8 Ω·m
5.0 A
1.0 oz
30 mm
80 mm
25 °C
Set parameters above and view the voltage drop color map and calculated values.
Ground bounce occurs when multiple drivers switch simultaneously, causing a voltage spike on the ground rail due to package lead inductance.
Vbounce = N × Lpkg × (dI/dt)
8
2.0 nH
0.50 A/ns
1.0 ns
Vbounce = 8.00 V — This is the ground bounce voltage when all drivers switch at once.
Lab 6: Power/Ground Plane Resonance
Parallel power/ground planes form a cavity resonator. Resonant modes create standing waves with impedance peaks at specific frequencies determined by board dimensions.
fm,n = (c / 2√εr) × √((m/a)² + (n/b)²)
where a,b = board dimensions, m,n = mode indices
100 mm
80 mm
4.3
1
0
Select mode indices and board dimensions to see the resonant standing wave pattern.
Track 10 Quiz: Power Integrity
1. What determines the target impedance of a PDN?
Target impedance Z = V_ripple / I_load. This sets the maximum acceptable PDN impedance across all frequencies.
2. Anti-resonance between two parallel capacitors occurs:
Anti-resonance occurs at a frequency between the two SRFs, where one cap is inductive and the other is capacitive. Their impedances partially cancel in the denominator, causing a peak.
3. How does increasing copper thickness affect IR drop?
Thicker copper means larger cross-sectional area, which directly reduces DC resistance (R = rho * L / A), thereby reducing IR drop.
4. Ground bounce voltage is proportional to:
V_bounce = N * L * dI/dt. More simultaneous switching drivers, higher inductance, and faster edges all increase ground bounce.
5. Which capacitor parameter primarily dampens anti-resonance?
ESR provides damping at resonance and anti-resonance. Higher ESR reduces the Q factor and flattens impedance peaks, though it also raises the minimum impedance.
6. Plane resonance frequencies depend on:
f(m,n) = (c/2*sqrt(er)) * sqrt((m/a)^2 + (n/b)^2). The resonant frequencies are determined by the cavity dimensions (a, b) and the dielectric constant (er).