Why does the Ethernet interface circuit need to be connected to GND through resistors and capacitors?

linchichang

Why does the Ethernet interface circuit need to be connected to GND through resistors and capacitors? [Copy link]

 

As shown in the figure, we can see that the Ethernet interface differential signal is connected to resistors and capacitors, and the other end is grounded. In addition, every two resistors share a capacitor. What are the functions of these resistors and capacitors?

mounthill

50 ohm impedance matching and differential common mode filtering circuit

linchichang

mounthill posted on 2018-11-18 10:59 50 ohm impedance matching and differential common mode filtering circuit

In other words, this structure of connecting a capacitor to GND between two resistors is used to filter out common mode interference on the differential line?

cruelfox

The resistors are used for impedance matching at the receiving end, and the capacitors are only used to block DC and make one end of the resistors equivalent to ground.

linchichang

cruelfox posted on 2018-11-18 14:57 The resistor is used for impedance matching at the receiving end, and the capacitor is only used to block DC and make one end of the resistor equivalent to ground.

Is what the brother above said right?

曹伟1993

Resistors are used for impedance matching. When communicating, both parties need impedance matching. I feel like capacitors are used for filtering.

曹伟1993

Resistors are used for impedance matching. When communicating, both parties need impedance matching. I feel like capacitors are used for filtering.

QWE4562009

What is impedance matching? Doesn't that mean there is an extra load loss?

PowerAnts

cruelfox posted on 2018-11-18 14:57 Resistors are used for impedance matching at the receiving end, and capacitors are only used to block DC and make one end of those resistors equivalent to grounding.

Is it the receiving end impedance? Or the transmission line impedance? Find it out

PowerAnts

The receiving end is already 50 ohms, what is the use of connecting another 50 ohms? Only when the terminal resistance is 50 ohms = the transmission line impedance is 50 ohms, the standing wave ratio is 1, and the line is completely matched