AD9613 input circuitry

Dear Sir.

I am using the circuit for single ended to double ended outputs .

The outputs are fed into a AD9613 .

I apply a signal of 2V @ 1kHZ at the input , I get no outputs at the resistor R97,R102.

Please Advise.

Ephraim Oved

Schematicad9613.pdf
  • 0
    •  Analog Employees 
    on Mar 14, 2016 7:46 PM

    Hi Ephraim,

    I do not see resistors R97 and R102 in your schematic.  However, if your input signal is at 1kHz it is likely being attenuated because of the input network (RC response likely does not extend that low in frequency).  I'd suggest increasing the frequency of your input signal (try 1-10MHz).  I would suspect you'd find that you can then see the input signal in your FFT as it would no longer be attenuated by the input network.

    Regards,

    Jonathan

  • Hi.

    The resistors are R57,R62,R46,R51.

    I have copied this design from Analog Devices .

    Do I need to install T5 , I recall that I saw that T5 was not installed ?.

    I will check later the input frequency .

    Please Advise.

    Ephraim Oved.

  • 0
    •  Analog Employees 
    on Mar 14, 2016 8:29 PM

    Hi Ephraim,

    If you have copied the AD9613 evaluation board then T1 and T4 are DNI.  In the layout the footprints for T1/T2 are combined and T4/T5 are combined.  This allows for the input network to be interchanged between the default double balun input network with T2/T3 and T5/T6 and the single transformer input network (T1 and T4).  Note that the evaluation board schematic shows T1/T4 (T301/T305) as DNI.  I'd also recommend comparing component values to the BOM that is linked form the AD9613 documentation to get the recommended component values.  Keep in mind that these components were chosen to provide the best performance over several hundred MHz of operating range and should be optimized for specific frequencies/applications.

    Regards,

    Jonathan