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.

  • Resolved

TRF370417: LO output with DC IQ inputs

Expert 1040 points

Part Number: TRF370417

Hello 

In my application I need to output the LO from the modulator, i.e to use I=1 and Q=0. So  the IQ mod RF output is a CW at LO frequency at a decent power level (~-5dBm)

My DAC is DAC38J84 or DAC3484, I am using the app note SLUA647a figure 15 in order to design the level shifting circuit for the Modulator VCM=1.7V

My concern is that whether I will still be able to output the LO as is from the modulator, now that I have external DC bias on the IQ mod inputs. 

Thanks

Izik

  • You can use the TRF370417 to output the LO from the modulator using external DC, if there is a voltage difference between I and Q inputs.
  • Expert 1040 points

    In reply to Abdallah Obidat:

    Thank you for your answer. What would be the I and Q DC voltage levels in this condition?
  • In reply to Izik:

    If I understand your question correctly, you would like the modulator to produce the LO as an output. In your example, I = 1, Q = 0, so you have 1V DC between I and Q. If this is the case, then the LO would shift this to the LO frequency as your output. Is this what you are asking?
  • Expert 1040 points

    In reply to Abdallah Obidat:

    So this means that the I voltage is 2.2V and the Q voltage is 1.2? (TRF370417 Vcm=1.7)
  • In reply to Izik:

    Yes, I believe so. You should also check the DAC datasheet and verify that it can handle those voltages.

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.