• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 821 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADC12J2700EVM

wening fang
Prodigy 55 points
Other Parts Discussed in Thread: ADC12J2700EVM, ADC12J2700

The document "ADC12J2700EVM and ADC12J1600EVM User's" mentioned  "Transformer-coupled signal input network allowing a single-ended signal source from 400 MHz to 3GHz". How to understand this feature? Does it mean that signal below 400MHz  may not be accepted by this evaluation board ?

  • 0
    TI__Mastermind 43870 points

    Hi User

    The standard configuration of the EVM uses the on-board balun path for the input signal. This is limited to approximately 400MHz to 3000 MHz signals for best performance. The balun response drops off below 400 MHz and above 3 GHz.

    The board can be reconfigured to allow external differential inputs (either DC coupled or AC coupled). In that configuration you can use a differential source such as an amplifier evaluation board, or balun board, etc. To reconfigure the board you will need to remove C3 and C5, and install C1 and C6. For low frequency AC coupled inputs I would recommend values of 0.1uF. For DC coupling, 0 ohm resistors can be installed in place of capacitors. When driving in DC coupled mode the common mode voltage of the differential inputs should be referenced and controlled by the ADC VCMO output voltage. Please refer to the schematic snapshot below, and the design package information in the ADC12J2700EVM product folder for more details on the location of these components.

    I hope this is helpful.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    Prodigy 55 points
    Thanks for your reply.
    In fact , in most of cases, the signals to be collected on our equipment may range from 2.5Mhz to 10MHz. Does that mean
    the A/D chip on the board can support them as long as they are converted to differencial type. Surely,
    the board has been reconfigured to allow external differencial inputs based on your suggestions.
  • 0 in reply to wening fang
    TI__Mastermind 43870 points

    Hi

    The ADC12J2700 device has excellent performance with inputs from DC to 3 GHz.

    If you DC couple a differential amplifier output (or other differential signal) to the EVM inputs you will get good performance. The only constraint is that the common mode voltage of the applied differential signal must be close to the Vcmo (common mode output) voltage output by the ADC device. The Vcmo voltage and a ground reference are available on the Vcmo 2-pin connector near the VIN+ SMA connector.

    Best regards,

    Jim B