we are use the IC AD8130 ,
we offer vcc +5v vss grand,
but can't output single.
if we offer vcc +5v vss -5v,
the output is right.
so how can offer vcc +5v vss grand, to marker output is right.
The amplifier is not getting the correct output at a single supply because the input signal is outside of the valid input common-mode range of the AD8130. The part specifies an input common mode range of 1.25V to 3.8V at a single supply to operate properly. A CVBS signal will go from 0V to 1.073V, so your amplifier is basically not seeing anything. With a dual supply, the input common mode range is extended from -3.8V to 3.8V (assuming +/-5V), so the amplifier can still see the input signal.
You can get this working on a single supply by biasing the input signal at mid-supply. This can be implemented by placing a resistor divider from the positive supply to ground and connecting this to the input as in the circuit below:
You will need to be careful with the resistors that you use so that you ensure the proper matching of impedances. Am I correct in assuming that you are using a 75ohm RGA cable?
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