All Questions
Tagged with differential ethernet
37
questions
5
votes
5
answers
978
views
Is the voltage on the negative of a differential pair actually below the ground voltage used to generate the signals?
Apologies if it’s obvious but I always hear that differential pairs have a negative and positive waveform (one on each line) that’s opposite. Now I get that you could choose whatever value or point “...
- 667
0
votes
0
answers
56
views
Interface Ethernet voltage
I just want to know what are the voltage levels on the Ethernet differential lines (both single ended voltage level wrto ground & different voltage between the pairs). I haven't measured the ...
- 1
4
votes
1
answer
550
views
10/100 Ethernet Routing Review
I know it is a big favor to ask, but this is my first ethernet design, so could you provide input on the routing from connector to mag and from mag to PHY? Is it fine or how can I improve it?
Really ...
- 345
3
votes
2
answers
2k
views
Is there a maximum differential skew in Ethernet communication?
I am working on a device that runs 100 Base-T.
When routing the differential pairs I was wondering if there is a maximum differential skew specified somewhere and if so, what is it? Is there a formula,...
- 61
1
vote
1
answer
172
views
Ethernet PHY RMII waveform without LAN Cable connected
Is the below waveform that I am getting in TX- line of Ethernet (PHY Used - LAN8700) correct? (Waveform obtained without connecting the LAN cable).
Using RMII mode in the PHY. R801 & R803 (pin 1) ...
user220456
2
votes
2
answers
286
views
Ethernet differential signals
I've 2 questions on Ethernet design:
Suppose I am using a current mode Ethernet PHY which requires termination resistor of 49.9 ohms to VDD on the Ethernet differential lines.
Can I increase the ...
user220456
0
votes
3
answers
682
views
Splitting of a differential signal
Can the Ethernet Tx and Rx signals (Using all 4 pairs; RGMII interface) be split into 2 so as to connect to 2 RJ-45 connectors, but only 1 will be used at a time. In general, can we split any ...
user220456
1
vote
1
answer
81
views
What are the recommended differential trace characteristics for Power over Ethernet input section?
I've been looking through a few application notes for Power over Ethernet front ends such as Microchip AN3468 and Skyworks AN1130.
I can't figure out what the characteristic impedance of the ...
- 140
-1
votes
1
answer
2k
views
What are the voltage levels in 100 Base-TX Ethernet?
I know what the differential voltage looks like. If you measure across Tx+ and Tx- it goes from -1V to 0V to 1V and so on, but how are these voltage levels actually transmitted?
Does Tx+ go from 0V - ...
- 61
2
votes
1
answer
714
views
What voltage difference should I use for 10BASE-T?
Looking through some resources about the electronics behind ethernet, specifically the 10BASE-T standard, I've found some conflicting information about what the voltage differential should be for the ...
- 160
2
votes
1
answer
416
views
Routing ethernet differential pairs over ground plane
I am routing a flexible PCB which connects a panel-mount ethernet connector (without integrated magnetics) to a rigid PCB which contains the ethernet magnetics. I plan to route the differential pairs ...
- 21
1
vote
2
answers
1k
views
What is Ethernet diff. pair referenced to between connector and magnetics
This is a little bit confusing part. I clearly understand that in ethernet cable fields are coupled between wires of differential pair. On PCB on IC/PHY side it is also known that differential pair ...
- 11
1
vote
0
answers
365
views
Which differential protocol to use when redriving Ethernet?
I want to redrive a 100-BaseTX signal on a board. The signal is to be redriven 3 times (by the same setup). On one end is a STM32 NUCLEO-F767ZI board, and on the other end is a GbE switch including ...
- 166
4
votes
1
answer
7k
views
Should Ethernet MDI Pairs all be Length Matched (Inter-Pair) before going into magnetics?
I've been trying to find information for the above question and I can't seem to find anything. I have 1000 BASE-T lines coming from an Ethernet cable to a PCB mounted connector. I'm pretty much ...
- 107
1
vote
1
answer
289
views
Special requirements 100Mbps (Ethernet) connection to PCB
Is there any special requirements/limitations to how 100Mbps Ethernet conductors can be connected to the PCB?
For instance in the design prompting the question I have a Ethernet connection entering ...
- 11