I require to convert RGsB (Gs means "Sync on Green") signals of a Single Ended video stream into Differential output.
I researched and found AD8134 to be suitable for the job. I developed an evaluation board on the resources available on Analog Site, and I looked at following discussion to create a board for AD8134 (I used the designs for AD8142 (same as AD8134) in the answer of AnnaFeB ):
However, in my card i kept the option to give a "negative 5" volt supply. In my case, i have no use for Vsync, Hsync and Sync Level pins (atleast that is what i think, since my Sync signal is on GREEN line), so there fore i have left these three signals "DISCONNECTED"
My issue is that once i start the board, power it up at "Positive and Negative 5 volts", and give no input, i get strange results on my outputs. the Red outputs, show no value, the green outputs show "negative 1 volt", while the blue output shows "Positive one volt". When i give an Input signal of "+1 volt" at all 3 positive inputs ( the negative inputs are grounded), i receive following outputs:
1) R+ and R- show nothing
2) G+= -1, G- = -2
3) B+= +2, B-= +1
I do not think this working correctly, does this have something to do with the three signals i left unconnected? please help..
Please do the following:
1. Connect a 17.3 or 38.3 ohm resistor between ground and inverting pin (negative input) of AD8134. Each of the negative input of R,G and B should have this for termination purposes.
2. If item 1 does not help, follow the level-shifting of sync pulses on page 17 of the AD8134 datasheet.
Let me know if this works.