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Hello
I designed a 4k-SDI dual 1 to 4 distributor using LMH1219 as equalizer and LMH1228 as driver as you see in the block diagram.
This is my EQ and DR schematic
In my design I have to use back panel and so I don't have on board BNC connectors.
This is my back panel's picture
You can see my EQ circuit on PCB
And DR circuit:
I tried to have space between EQs and DRs and power section
Also on the back panel I draw a good GND plane between equalizers and drivers
With all this considerations When I enabled all drivers to have output, I can not get more than 25m with Belden-1694 on equalizers while datasheet says it can work with 75m. when I turn off drivers, equalizers will lock more than 60m(I can see on Lock LED). I don't know why drivers effect on equalizer signal and what should I do to prevent this problem. Do you have any advice?
If there is a good simulation tools that I can use to understand where is the problem, please introduce me.
Thanks.
Hi Patrick,
Thank you for sending this detailed information. I want to confirm a few things
Let me know if you have any more questions or would like me to elaborate on anything.
Best Regards,
Nick
Hi Nick
Thanks for your consideration.
Also I simulated my PCB with Ansys SIwave for SYZ and you can see the result in the following image.
This is SYZ parameters between 4 output SDI from 2x LMH1228 and 2 input SDI from 2x LMH1219
With my test results I know that I have problem because of crosstalk and if I could increase space between equalizers and drivers it will be better and I can get about 45m but in this project I can not increase the space. So I want to know is there any solution for me?
I need to mention that when I turn off driver's power and read lock of equalizer, It can lock more than 70m but I don't know how drivers effect on equalizers.
Hi Patrick,
Thanks again for the information.
How SigCon can help? As I know the best answer occurs with the default registers and with default registers I have problem too.
I can not increase the space. So I want to know is there any solution for me?
Set the settings with 0 EQ and 0 deemphasis to see if that helps. Otherwise, the changes that you will make will have to be with the layout.
Best Regards,
Nick