ADG918 high video leakage when using DC bias

is there a change in video leakage with or without applying 0.5V DC bias?

I measured and saw a difference:

without bias: 2mV pk-pk

with bias: 300 mV pk-pk

the bias was applied using a 1.5V battery with voltage divider of 100 ohm and 200 ohm to achieve 0.5V bias. I used battery to have cleanest possible power supply.

I require the video leakage to be 2mV also with DC bias. is there any reason why I didn't get that?

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  • 0
    •  Analog Employees 
    on Sep 3, 2018 7:45 PM over 2 years ago

    Hello,

    Can you please comments on the following questions before I can come to a conclusion about the video feed through level when 0.5V DC bias is applied

    • What voltage level you are applying at VDD pin
    • What voltage level you are applying at Vctrl pin, from the plots it looks like you are applying ~3V, ADG918 is only operation up to 2.75V
    • On which pin you are applying the DC bias
    • On which pin you are measuring the video feed through
    • While measuring video feed through is RF1 and RF2 pins left floating as shown in figure 24 of ADG918 data sheet

    Thanks

    Naveen

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  • 0
    •  Analog Employees 
    on Sep 3, 2018 7:45 PM over 2 years ago

    Hello,

    Can you please comments on the following questions before I can come to a conclusion about the video feed through level when 0.5V DC bias is applied

    • What voltage level you are applying at VDD pin
    • What voltage level you are applying at Vctrl pin, from the plots it looks like you are applying ~3V, ADG918 is only operation up to 2.75V
    • On which pin you are applying the DC bias
    • On which pin you are measuring the video feed through
    • While measuring video feed through is RF1 and RF2 pins left floating as shown in figure 24 of ADG918 data sheet

    Thanks

    Naveen

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