I was designing an EMI Filter for the CE102 standard. I was a bit confused on how to provide noise source to the circuit, since (as of my knowledge) EMI noise enters our system by parasitic capacitance or inductance coupled to power lines.
Also, I provided a noise source to the circuit as given below. Please correct me if I am wrong.
The easiest way to test or simulation ground noise or CM noise is with a series generator using a CM choke. We used to use an audio and RF power amp., brushed motors twisted along cables, and large inductive pulses.
But you could also use a square wave using dry NC contacts in series with power relay coil.
But you should read the standard.
You can even inject a CM 6kV lightning bolt with 30 ns rise time. Use 100 ohm series R into an ideal CM transformer as CM.
A typ. Transformer is not as balanced as a CM choke which requires 0.1% tolerance to suppress 60dB , then the Pi filter provides the LPF breakpoint. check the specs. A typical iron transformer power supply attenuated 70 dB for lightning on a linear DC output with a line filter. SMPS supplies vary widely.
Go fetch Fully Understanding CMRR in DAs, IAs, and OAs Pete Semig Analog Applications Engineer-Precision Linear TI site
