Conducted EMI differential-mode estimate
Trapezoidal pulse harmonics, user-defined LISN transfer and a damped LC filter estimate.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Assumptions
- Pulse is an ideal rectangular waveform convolved with a finite ramp; harmonic amplitude uses sinc smoothing. Duty refers to pulse area, and results are discrete RMS Fourier lines.
- LISN value is a user-supplied effective differential-mode transimpedance, not a universally valid 50 Ω conversion.
- The filter is an ideal second-order voltage-transfer estimate with specified damping. Common mode, parasitics, spread spectrum, detector bandwidth, quasi-peak detection and test setup are absent.
- The entered limit is a comparison target only. This calculator does not assert EMC compliance.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Pulse-current height
- 2 A
- Pulse area duty
- 0.4
- Switching frequency
- 200000 Hz
- Symmetric ramp smoothing time
- 2e-8 s
- Number of harmonics
- 50
- Effective DM LISN transimpedance
- 25 Ω
- User-selected comparison limit
- 60 dBµV
- Differential filter series L
- 0.00001 H
- Differential filter shunt C
- 0.000001 F
- Effective filter damping resistance
- 1 Ω
Results
- Largest filtered modeled harmonic
- 123.179 dBµV
- Maximum additional attenuation required
- 63.1792 dB
- Largest modeled harmonic
- 146.611 dBµV
- Frequency of largest filtered harmonic
- 200000 Hz