EMC/EMI Calculators
16 free calculators with formulas and worked examples.
Shielding effectiveness, EMI filter design, ferrite bead selection, ESD/TVS diodes, radiated emission estimates, ground plane impedance, and crosstalk calculators.
RF Shielding
Calculate electromagnetic shielding effectiveness, absorption loss, reflection loss, and skin depth. Evaluate enclosure materials per MIL-STD-285.
Ferrite Bead
Calculate ferrite bead impedance, insertion loss, and DC voltage drop at any frequency. Select EMI filter beads for power supply decoupling.
LC EMI Filter
Design LC EMI filters for conducted emissions compliance. Calculate inductance, capacitance, cutoff frequency, and attenuation for CISPR 22/32 and FCC Part 15. Free, instant results.
ESD TVS Diode
Calculate TVS diode clamping voltage, breakdown voltage, and peak pulse power. Select ESD protection for IEC 61000-4-2 circuit design.
CMC Impedance
Calculate common mode choke impedance, insertion loss, and Q factor at any frequency. Design EMC filters for CISPR 25 conducted emissions compliance.
Decoupling Cap EMC
Calculate decoupling capacitor impedance, reactance, and self-resonant frequency. Select bypass caps by package for EMC power integrity.
ESD Clamp
Calculate ESD clamp diode peak current, power dissipation, and clamping ratio. Verify TVS protection for IEC 61000-4-2 compliance.
Radiated Emissions
Estimate radiated emissions from PCB current loops using the small-loop model. Compare E-field against CISPR 22/FCC Class B limits instantly.
Ground Impedance
Calculate PCB ground plane AC impedance, skin depth, and inductive reactance vs frequency. Analyze ground return paths for EMC compliance.
PCB Crosstalk EMC
Analyze PCB trace crosstalk from capacitive and inductive coupling. Calculate coupling voltage and dB isolation for EMC pre-compliance.
Ripple Filter
Calculate LC filter attenuation, resonant frequency, and output ripple voltage. Design power supply EMC filters for ripple rejection.
Cable Shield
Calculate cable shielding effectiveness and transfer impedance vs frequency. Evaluate coaxial and shielded cable EMI performance for EMC compliance.
Chassis Resonance
Calculate the lowest resonant frequency and TE modes of a metallic enclosure. Identify cavity resonance problems for EMC shielding design.
EMI Margin
Calculate EMI compliance margin with measurement uncertainty and safety margin. Predict CISPR/FCC pre-compliance test pass or fail instantly.
Conducted EMI Filter
Design an LC filter for CISPR 22/FCC conducted emissions compliance. Calculate required inductor and capacitor values for target attenuation.
DM EMI Filter
Design a differential mode LC EMI filter. Calculate corner frequency, attenuation, and impedance for SMPS output noise suppression.
About EMC/EMI Calculators
Electromagnetic compatibility engineering ensures that electronic devices neither emit interference that disrupts other equipment nor are susceptible to interference from their environment. Regulatory frameworks (FCC Part 15 in the US, CISPR 32/EN 55032 in Europe) define emission limits; IEC 61000 series defines immunity requirements.
Radiated emissions arise from differential-mode currents (intentional signals on PCB traces) and common-mode currents (unintentional currents on cables and chassis). The dominant emission mechanism at frequencies above 30 MHz is typically a resonant cable acting as an antenna driven by common-mode voltage. Cable shield effectiveness calculators predict the isolation provided by braided or foil shields as a function of frequency and termination quality.
Ferrite beads are lossy inductors that suppress high-frequency common-mode noise without the ringing associated with reactive LC filters. Their effectiveness depends on impedance at the target frequency — datasheets specify impedance at 100 MHz, but actual performance at other frequencies requires interpolation from the impedance vs. frequency curve. ESD protection TVS diodes clamp transient voltages to safe levels; selection requires matching clamping voltage to IC abs-max ratings and peak pulse current to diode ratings.
Ground plane impedance is surprisingly high at RF: a solid plane has inductance (~1 nH/inch), and at 100 MHz a 10 cm return path has ~6 Ω impedance — enough to create significant noise voltages. Splitting ground planes (digital/analog/RF) is often counterproductive; a single solid plane with careful current path routing is usually superior. PCB crosstalk calculators quantify capacitive and inductive coupling between adjacent traces.