Dear Sir,I am working on ADA4858-3 and I am facing some technical issue.
I designed Amplifier Driver using ADA4858-3 driving and equalizing a 100M VGA Cable ,based the application note written by an ADI application engineer via below link. Please check the attached schematic for my design.
I have serious smearing problem in the VGA output image even worse than the situation without this ADA4858-3 driver circuit.
Would you please help to check and give some professional advice?
will look into this. ill update you soon.
I simulated a part of your circuit and it turns out that your magnitude vs. frequency is way far compared to the figure 5 of your reference. I've noticed that the value of your RG is 56ohm compared to the 15ohm on the app note.
the magnitude level was improved when i tried to change R109 (56R) to 15R, and for the load, try to remove R127 (75R) and R116(150R).
Attached in this thread is the simulation i made based from your circuit. Kindly check if I put the right components in the circuit simulation. Try tweaking some components and see improvements.
Many thank for your reply.
We will have a try to change R109 (56R) to 15R at first.
What's more, In the previous exisiting actual circuit, R116 was NC, and the ADA4656-3 R/G/B output were connected directly to a video processor behind (do not via a cable), maybe the series resister R127/ R160 / R156 75ohm could not be removed.