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Line Impedance Stabilization Networks (LISN)
A: Line Impedance 
Stabilization Networks 
(LISN)
A line impedance stabilization network serves three purposes:
1. The LISN isolates the power mains from the device under test. the power 
supplied to the DUT must be as clean a possible. Any noise on the line will be 
coupled to the EMI Receiver and interpreted as noise generated by the DUT
2. The LISN isolates any noise generated by the DUT from being coupled to the 
power mains. Excess noise on the power mains can cause interference with the 
proper operation of other devices on the line.
3. The signals generated by the DUT are coupled to the EMI Receiver using a 
high-pass filter, which is part of the LISN. Signals that are in the pass band of the 
high-pass filter see a 50-Ω load, which is the input to the EMI Receiver.