# Capacitive and Inductive Coupled EMI model

• newengr
In summary: There are a number of ways that microwave radiation can affect an integrated circuit. One of the most common ways is through the use of shared impedance coupling. This happens when two circuits share the same load, like a power supply or antenna, and the radiation from one circuit affects the operation of the other. This can cause problems with the data transmission on the circuit, as well as the overall operation of the circuit. Other ways that radiation can affect an IC are through the use of node-to-node coupling and through the use of surface waves. Node-to-node coupling happens when the radiation from one circuit affects the operation of another circuit directly. This type
newengr
TL;DR Summary
I would like to create an EMI equivalent circuit model considering both inductive and capacitive coupling in one.
I am new to EMI modeling and just looking into it. I would like to create a circuit schematic to represent the inductive and capacitive coupling paths in one schematic. All that I've been able to find online is references discussing each independently. Is this the best approach if you want to consider both? Any references or suggestions for modeling both together would be helpful. Or if there's a reason not to, that would be helpful too.

What is the source of the EMI ?
What is the target ?

Directional couplers and short antennas can be hard to express on a circuit schematic.

The source of the EMI is a MOSFET switching on a DC bus. The target are nearby circuits referenced to a the midpoint of the bus or the -DC rail; both cases work. I extracted the parasitics which include capacitive coupling and inductive coupling terms using Q3D. I have the netlists for capacitive and inductive separate so I can draw the circuit for each. The challenge for me is trying to combine them.

I think combining them would be best if I can model my loads and source well enough. Then my circuit would have the appropriate voltage and current waveforms. Or is it better (or equivalent) to just take my voltage waveform and use it to analyze capacitive coupling the use my current waveform to look at inductive coupling? O and I'm neglecting radiated coupling at this point.

What form does the mutual C and L data take.
Does it employ nodes similar to a spice model?

If you can define the nodes on the EMI generator, and the nodes on the sensitive target, then you might define a scattering matrix that combines the reactive currents being delivered to the target.
Induced currents would appear between two nodes and could be simulated using transformers with coupling coefficients. Capacitive currents due to voltage changes would be between nodes. The method of moments might be considered.

I don't think EM radiation will be important for such a small space. It will all be near field.

newengr said:
The source of the EMI is a MOSFET switching on a DC bus. The target are nearby circuits referenced to a the midpoint of the bus or the -DC rail
Probably shared impedance coupling will dominate the crosstalk, but without seeing your schematic and layout, it's hard to know. Can you share the schematic and layout?

## What is a capacitive and inductive coupled EMI model?

A capacitive and inductive coupled EMI model is a mathematical representation of the electromagnetic interference (EMI) that occurs between two electronic circuits due to the coupling of their capacitive and inductive components.

## What is the difference between capacitive and inductive coupling?

Capacitive coupling occurs when two circuits are connected through a capacitor, allowing the flow of AC current between them. Inductive coupling, on the other hand, occurs when two circuits are connected through an inductor, causing a magnetic field to be induced between them.

## What are the effects of capacitive and inductive coupling on electronic circuits?

The effects of capacitive and inductive coupling can include signal distortion, noise interference, and even damage to electronic components. This can result in malfunctions, reduced performance, and even complete failure of the affected circuits.

## How can capacitive and inductive coupling be mitigated?

To reduce the effects of capacitive and inductive coupling, techniques such as shielding, filtering, and proper circuit layout can be used. These methods help to minimize the interference between circuits and improve overall EMI performance.

## What are some real-world applications of capacitive and inductive coupling?

Capacitive and inductive coupling can be found in various electronic systems, such as power supplies, audio amplifiers, and communication devices. It is also commonly used in wireless charging technology, where a magnetic field is used to transfer power between two devices.

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