• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 366 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.

DAC5687 Configuration for different IF signal path

Jin Kyung Han
Expert 1520 points
Other Parts Discussed in Thread: DAC5687

Hello

I would like to configure as the below. These are 4x interpolation.

CH A : Input IF= 120MHz

CH B : Input IF= 75MHz


Additional question, In case of  same as Channel A, If set usb(data to DACB is inverted to generate upper-sideband output.) of Addr 0x04h, What results it give?

I atatched file it has detail configuration I want.

Thanks

5344.DAC5687_WTK_0324.ppt

 

  • 0
    TI__Guru 66014 points

    Jin,

    Please let me review and get back to you.

    -Kang

  • 0 in reply to Kang Hsia
    Expert 1520 points

    Kang

    Thank you for reviewing my issue.

    -Jin

  • 0 in reply to Kang Hsia
    Expert 1520 points

    Kang

    Have you reviewed the question?

    My customer is still waiting for answer regarding to the question.

    Thanks and Best Regards

  • 0 in reply to Jin Kyung Han
    TI__Guru 66014 points

    Hello Jin,

    After reviewing the customer's frequency planning, either Channel A or Channel B upconversion to 75MHz and 120MHz is realizable. The Channel A upconversion to 120MHz can be realized with HP/HP approach, while the Channel B upconversion to 75MHz can be realized with HP/LP approach. 

    There are limitations to these configurations:

    1. Since you may only set HP/HP or HP/LP mode one at a time, (not both), it is not possible to create channel A while creating channel B at the same time. 

    2. The same applies to Fs/2 CMIX approach. The Fs/2 CMIX applies to both channels. Therefore, only one type of channel output may be created.

    3. The HP/HP or HP/LP mode will have limitation on the input/output bandwidth due to overlapping filter response of FIR1/FIR3.

    Please see attached spreadsheet for our recommendations on channel configuration. The customer may input their desired channel response in the yellow boxes.

    Note: the usb(in 0x04h) is used in complex IF mode where channel A and B are upconverted in complex fashion. Since the HP/HP or HP/LP mode are meant to be independent operation (real IF), the usb register will not have an impact on the output.

    -Kang

    DAC5687_MixModes.xls
  • 0 in reply to Kang Hsia
    Expert 1520 points

     Hello Kang

    According to the your answer,

    finallly The DAC5687 can not be configured operating different frequency at a same time. My customer wants the DAC5687 to be used for Repeater which need RX path and Tx Path in FDD(Frequency Division Duplex) full Dupulex Mode.

    Actually the customer asked me to compare AD9777 of ADI with DAC5687. All things of DAC5687 are OK but this function(independant setting Complex mix) does not meet ADI..

    Only same frequency in chA / ChB can be configured operation at a same time.

    Thanks and Best Regardds

  • 0 in reply to Jin Kyung Han
    TI__Guru 66014 points

    Jin,

     Looking at the AD9777 datasheet, I do not believe the AD9777 has the ability to change the interpolating filter to high pass/low pass function. All the interpolating stages remains fixed in low pass mode. It seems only the DAC5687 has this feature.

    If the customer is using the AD9777 with complex mixer mode, then the DAC5687 has the complex mixer with either coarse mixing (fs/2, fs/4) or fine mixing (NCO). I believe the customer may use these building blocks to reach the same frequency planning as AD9777.

     Best Regards,

    Kang Hsia