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TRF370315: Minimum Baseband Frequency

Part Number: TRF370315

The Electrical characteristics in the datasheet repeatedly state that they are using a Single 4-MHz CW baseband input tone, differential-ended 196 VRMS. Can you tell me the lowest frequency baseband that can be used with the TRF370315?

Thanks for your help with this!

Richard Elmquist

  • The TRF3711 BB output supports down to DC (I hope that is low enough for you :) ). The upper frequency is set by the programmed low pass filter corner.

    --RJH
  • In reply to RJ Hopper:

    RJ,
    Thanks for your quick reply!
    Have a wonderful day!
    Richard Elmquist
  • In reply to Richard Elmquist:

    RJ,
    The customer has asked additional questions:
    "For the TRF370315, what frequency range of baseband does it support? It seems to me since the electrical characteristics are performed with 4 MHz CW tones into the baseband inputs, it can at least go down to there, far below 350 MHz, do you agree? I don’t necessarily need to pass DC, I just need to find out how far down in frequency I can go for baseband inputs."
    I am just not sure what he is asking, but I think that you might be able to interpret it.
    Thanks for your help with this!
    Richard Elmquist
  • In reply to Richard Elmquist:

    Let's get our nomenclature correct. This is a demodulator. The input is RF. The *output* is baseband. The input RF frequency supports down to 350 MHz on the TRF371109.

    The BB output supports DC to 25 MHz (max) and is dependent on the programmed low pass frequency corner frequency. The programmed LPF settings operate from 700 KHz to 15 MHz with a bypass that extends to 25 MHz. Note this is IQ BB frequency so it will support twice that in terms of signal BW (i.e 1.4 MHz - 50 MHz BW).

    --RJH
  • In reply to RJ Hopper:

    RJ,

    Thanks for your response! I will send this to the customer.

    The customer also made the following statement:

    Just to make sure, I am interested in baseband input performance below 350 MHz, not RF out.    I am pretty sure it works below since a 4 MHz CW tone is being sent to the baseband inputs for characterization of the parts.  This what leads me to believe that the 1dB knee at 350 MHz is the upper frequency of performance.

    Please comment on this. Thanks for your help with this!

    Richard Elmquist

  • In reply to Richard Elmquist:

    Richard:

    The customers response/question is confusing. The TRF3711 does not have a baseband *input*. The baseband is an *output*. It supports a baseband output of DC-15MHz with the programmable LPF and up to 25 MHz with LPF bypass. 4 MHz is just a point used for characterization.

    It sounds like the customer is interested in a modulator or mixer. If so, then the TRF3703/TRF3704/TRF3705 would suffice.

    For additional questions on the TRF3711, let's reference specific plots in the datasheet so we can be clear on the question.

    --RJH
  • In reply to RJ Hopper:

    RJ,
    The original question was on the TRF370315. Can you respond with your thoughts on this part. The TRF3711 might be a similar part, but is it the same part? Isn't the TRF370315 also a modulator? The customer is confused by the responses that state other part numbers. Can you please look at the questions posed and answer them in terms of the TRF370315? Or if the TRF370315 is not the proper part for the application please let me know so that I can try and answer the customer's questions.
    Thanks for your help with this!
    Richard Elmquist
  • In reply to Richard Elmquist:

    Am I loosing my mind. Was this post always about the TRF370315? How did I get TRF3711 in my mind? Looks like it is my mistake. Sorry for the confusing run-around.

    OK, let's reset on the TRF370315 (which is indeed a modulator). The baseband inputs on the TRF370x product can go down to DC. The input BB frequency range is DC - ~1GHz. There are 3 flavors in this family: TRF3703-33, TRF3703-15, and TRF3703-17. The last part designates the Vcm: 3.3V, 1.5V, 1.7V. If you are interfacing to a TI current sink DAC with a 3.3V common mode then the -33 part is best. Otherwise, I recommend the -17 device for best linearity.

    There is also a TRF370417 which operates down to 50 MHz and up to 6 GHz on the output. There is also the TRF3705 which offers a 0.25V Vcm for better interfacing with newer TI DACs. All flavors support BB input down to DC.

    --Russell
  • In reply to RJ Hopper:

    RJ,
    Don't worry about it. I sometimes wonder if I am working while I am working.
    Hopefully this will answer the customer's questions. I will let you know.
    Thanks for your help with this!
    Richard Elmquist