TX BUFFER

Hi singerhaha:
If you only simulate TX buffer and the input data is ideal,
I guess the duty cycle is not ideal.
Could you check the output waveform?
mpig

hi mpig09，thank you for your answer！But i don’t know the ralationship between my question with your answer.Could you explain more clearly！i am so eager for it
thank you again.

Hi singerhaha:
Because I don't know your testbench, so I "guess" your add a 100MHz noise on VDD
and input a ideal clock to driver your TX buffer.
If there are multistage in the TX buffer, the noise may effect the output signal of each stage.
1. rising time / falling time will different of each buffer.
2. jitter may obvious on each output stage.
I suggest you to check each stage if the TX buffer has multistage in your design.
If I have any mistake, please let me know.
mpig

hi mpig09，it's so kind of you！input data is random data，TX BUFFER consists of a predriver and main driver.I have checked both stages. What i cheked is differential signalings.Please let me know anything else should be cared during TX BUFEFERdesign?
now the case is when i use a sinenoise，no 分叉！when i use a pulse noise ，分叉 still is there.What shoud i do now?


singerhaha

jitter issues

hi eeweiboy :
could you tell me what helps result in the jitter issue?

nicer

Hi singerhaha:
If the problem is rising / falling time issue, you need to check the root cause at which stage.
==>Input a max. speed clock signal to your TX Buffer, and check which the difference between
rising time and falling time (the Trise - Tfall needs small)
If the problem is jitter, does the random data is ideal?
mpig

hi mpig09 :
the random data is ideal ！it's caused by random_data stream cell.random data's frequency is 1.6G, rising time/fall time is 40p.From this ,any problem?what confusing me is why a sine waveno 分叉.


singerhaha

Hi singerhaha:
What mean "what confusing me is why a sine waveno 分叉." ?
Does the waveform result meet your spec?
mpig

Hi singerhaha:
The waveform is p-n result?
Which view tool that you get the waveform?
If you use spice explorer,
you can use Tools --> Jitter vs time to get more detail info.
ex:long time jitter
long time duty variation
It will help to know the root cause.
If youhave any problem, please let me know.
mpig

如果是加了电源噪声才出现分叉，看看是不是电源噪声引入的DJ。

hi bebe00

加sine信号的噪声时是没有出现分叉，而加矩形波形的噪声就出现了分叉，为什么会这样?
谢谢
singerhaha