issue with AD8066

Dear Engineers,

i'm having issue with amplifier AD8066 when driving A/D converter AD9288-100,

i'm attaching schematics, and i need to remove or minimize R9 resistor, because i'm having smaller numbers of sine signal,

and also AD9288 has internal resistors on input and they are connected to Vdd with value 28k and to GND with 12kOhm,

and when i remove R9 then AD8066 will start clamping distortion probably,

please help me to identify what is badly designed,

Kind regards,

attachments.zip
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  • 0
    •  Analog Employees 
    on Jul 25, 2013 11:56 PM

    Hi bexizou,

    Thanks for using ADI products on your application. With regards to your circuit, could you provide the scope shots at the output of both AD8066 as well as the sine wave input on IC2A?

    I noticed that you are using high values of resistors. These large values will contribute more Johnson noise to your system. Could you try lowering the value of the following resistors: R5 and R6 to 1Kohms and R9 to 20 ohms, and check if there is a difference? You can also remove R2 on your circuit.

    Best regards,

    Emman

Reply
  • 0
    •  Analog Employees 
    on Jul 25, 2013 11:56 PM

    Hi bexizou,

    Thanks for using ADI products on your application. With regards to your circuit, could you provide the scope shots at the output of both AD8066 as well as the sine wave input on IC2A?

    I noticed that you are using high values of resistors. These large values will contribute more Johnson noise to your system. Could you try lowering the value of the following resistors: R5 and R6 to 1Kohms and R9 to 20 ohms, and check if there is a difference? You can also remove R2 on your circuit.

    Best regards,

    Emman

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