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DAC38RF82EVM: Can DAC38RF82EVM generate square wave signal？

XIaodie Hu
Prodigy 100 points
Part Number: DAC38RF82EVM
Other Parts Discussed in Thread: TSW14J57EVM, DAC38RF82

Hello engineers！

I hope that using DAC38RF82EVM can generate square wave signals with different frequencies, but I see the test examples are all sinusoidal signals with different frequencies.I have the following questions:

1,Can DAC38RF82EVM be used in combination with TSW14J57EVM to generate test signals?

2,How to set up or change the circuit so that the DAC38RF82EVM generates a square wave signal instead of a sine wave signal?

Thank you very much!

  • 0
    TI__Guru* 91947 points

    Xiaodie,

    You can generate a square wave output for CHA with the attached csv file. The problem you will have is that since the EVM has a transformer on the output, the square wave will get rounded off due to the transformer (see photo below). You would need to remove transformer T7 and use SMA's J6 and J7 for a differential output from CHA. The board does not have this option for CHB.

    To convert CHA, the user must do the following:

    Remove T7, L10, C398.

    Install L7 and L8 with proper pullup resistor values.  Install R248 and R241 with 0 Ohms.

    Replace C413 and C399 with 0 Ohm resistors.

    You will also need to change the bias voltage connected to these resistors. This will not be easy as it will require the +1.8V_VDDOUTA trace be removed from L7 and L8. One way is to install the new parts so that only one end is soldered to the board pad that is connected to IOUTAP/N and the other end is connected to an external supply voltage. Per the attached example, which explains how to properly terminate the output when interfacing to an amplifier, this would be 5V.

    Regards,

    Jim 

    6153.DAC38RF8x+LMH5401_interface.docx

    Regards,

    Jim

       6215.narrow_pulse.csv

  • 0 in reply to jim s
    Prodigy 100 points

    Dear Jim,thank you!

    I also want to ask you a few questions:

    What is the maximum frequency of sine wave and square wave generated by DAC38RF82EVM and TSW14J57EVM? Do you have a .csv file?

    Regards,

    Xiaodie

  • 0 in reply to XIaodie Hu
    TI__Guru* 91947 points

    Xiaodie,

    Using the DAC38RF82 in 81180 mode (Table 9 of data sheet), single channel, 8-bit real data, sampling at 9GHz, you should be able to get a 4500MHz output square wave using the attached .csv file.

    Regards,

    Jim

    2 sample square wave.csv