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When to use capacitive coupling in Ethernet networking?
The most common application where capacitively coupled Ethernet PHYs are used is in backplane applications where a single cap can be used to isolate the two nodes that are attached to the backplane using ethernet compliant connectors. Capacitive coupling may also be used in applications requiring a short cable less than 1 meter.
What kind of PHY do I need for Ethernet?
What you really need is a different variety of PHY, so called “backplane phy”. Those are specifically designed to work with capacitive coupling over PCB traces. The relevant standard is called 802.3ap.
Do you have to put two capacitor on the line?
In a case where you control both side of the connector, only one capacitor on the line can be mounted. But if you control only one side you have to put a capacitor two, in case the other side has nothing or has a transformer.
What is the line code for etherent 100 Mbit Ethernet?
Read the datasheet. Etherent uses various types of line codes to ensure that the transmitted data is DC balanced. 4b/5b is the line code used in 100 Mbit ethernet, and then it is transmitted with MLT-3 encoding. The 4b/5b code caps the number of ones and zeros you can get in a row.
Which is an example of inductive and capacitive coupling?
For example, in below circuit I tried to add capacitive coupling from AC mains and some radiated noise as inductive coupling (using a transformer model). Vs is the signal source 1V 1Hz sine wave. R_source is the output impedance. R_balance is the series resistor to make the transmission balanced.
How to reduce the coupling factor in a transformer?
The only possible suggestion I would make is to reduce the coupling factor in the transformer from 1 to something much smaller. You could even go on to use two pairs of coupled inductors fed from the same interfering source feeding each individual wire then changing the coupling facts also introduces a differential noise.