A spectrum analyzer standard input impedance is 50 ohms, so the voltage across that 50 ohms will be the voltage that is going to be evaluated in frequency domain to see where the equipment under test is meeting standards or not. At the output port, we connect a spectrum analyzer to investigate the frequency domain characteristics of the noise generated.
So most of the AC noise, generated by the equipment under test, is diverted to the output port of the LISN.
EMI FILTER DESIGN SOFTWARE SERIES
You can see that any AC current that is going into the equipment under test, would mostly be close through this capacitive coupling to the output port of the LISN, whereas only a little bit of current would be flowing through the series inductance. On the left-hand side, a LISN is connected to a power source, on the right-hand side, it's connected to the equipment under test, and in between, LISN operates as a filter. Let's look at the LISN first, what is shown here is one-half of a complete LISN. We'll talk about differential-mode and common-mode EMI, and we will illustrate the discussion using a simulation example based on a boost DC-DC converter. In this lecture, we will look into more details related to measurement of conducted electromagnetic interference, and the use of the line impedance stabilization network or LISN. Use computer-aided tools and simulations to verify input filter design View Syllabus.Design properly damped multi-stage input filters.Design properly damped single-stage input filters.Understand input filter design principles based on attenuation requirements and impedance interactions.Understand conducted electromagnetic interference (EMI) and the need for input filter.Techniques of Design-Oriented Analysis (ECEA 5706)Īfter completing this course, you will be able to:.Averaged-Switch Modeling and Simulation (ECEA 5705).Introduction to Power Electronics (ECEA 5700).We strongly recommend students complete the CU Boulder Power Electronics specialization as well as Courses #1 (Averaged-Switch Modeling and Simulation) and #2 (Techniques of Design-Oriented Analysis) before enrolling in this course (the course numbers provided below are for students in the CU Boulder's MS-EE program): You will be able to design properly damped single and multi-section filters to meet the conducted EMI attenuation requirements without compromising frequency responses or stability of closed-loop controlled power converters. After completion of this course, you will gain an understanding of issues related to electromagnetic interference (EMI) and electromagnetic compatibility (EMC), the need for input filters and the effects input filters may have on converter responses. This is Course #3 in the Modeling and Control of Power Electronics course sequence. This course can also be taken for academic credit as ECEA 5707, part of CU Boulder’s Master of Science in Electrical Engineering degree.