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TRF37C73: Operation down to 500kHZ?

Stephen Turner
Genius 3235 points
Part Number: TRF37C73
Other Parts Discussed in Thread: TINA-TI

Hi,

I'm designing an RF ampflier thats needs to cover the radio AM_FM bandwith, i.e ~500kHz to 120MHz. 

The TRF37C73 is spec'd down to 1MHz and I'd anticipate it would work below that as well. 

Question to TI is - do you have any results for this part at 500kHz and what value does the RF Choke need to be changed to?.  App note TIDU607 suggests a choke value of 4.7uH.  I'm giessing I'd need to double that to at least 10uH?.

Any help would be appreciated

thanks!

  • 0
    TI__Genius 11565 points

    Hi Stephen,

    Good work on finding the TIDU607 app note, the explanation and detail there is done well.  I ran some TINA-TI simulations of the TRF37C73 Reference Design, and found the following:

    Here is the TRF37C73 Reference Design at 1MHz sine signal, DC caps at 0.1uF, choke (L) = 4.7uH as per TIDU607"

    Now see the following at 500kHz with 9.4uH, double that of the recommended value at 1MHz:

    For completeness, I also ran a transient simulation at the high end of your frequency range (120MHz) with the choke (L) = 9.4uH:

    I will leave the decision up to you, but I would say your assumption works out reasonably well.  There are of course other simulations to run or choke values to test, but this is what I got from your starting point.  I encourage you to run these TINA sims for yourself to corroborate my findings, if you have the time.

    I will reach back out on the forum if I find anything about your design ideas or my sims that does not make sense (and run it past my team), and I will look to hear from you shortly.

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Genius 3235 points

    Hi ALex,

    Thank you for doing the sims in TINA-TI. Appreciate it.

    regards