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Op-amp selection assistance

Art Mecina
Genius 16785 points
Other Parts Discussed in Thread: THS3491, OPA2677

Hello Guys,

Good day.

Please help on selecting an Op-amp for our customer requirements below.

"I'd like to amplify the signal (in range from ~100kHz to ~4MHz) from my signal generator (Hantek DSO2D10), to be able to send it to a simple antenna (50 Ohm impedance, maybe just a coax cable will also work) and get around 50w of emitted signal power. The device will be in a Faraday cage to avoid possible interference with people already using those frequencies.

I'm not trying to build any kind of a radio transmitter or so. My goal is to just emit various frequencies in the air and inspect how those frequencies affect test objects (in near vicinity, around 1 or 2 feet away) in resonance with those emitted frequencies.

Which of your op amps would you use if you were to build such a thing?"

Thanks and regards,

Art

  • 0
    TI__Expert 3620 points

    Hi Art,

    We can't give you 50w of power, but the closest we have is probably the THS3491. You may want to look into a power op amp or RF power amp for this application. 4MHz doesn't really require a high speed amp, so if you would like I can forward this to another apps team to get you a better recommendation from one of those portfolios. The THS3491, while not exactly designed for this task, is pretty capable so take a look and let me know what you think. Sounds like a fun experiment.

    Best,
    Sam

  • 0 in reply to Sam Burnett
    TI__Genius 16785 points

    Hello Sam,

    The customer reviewed the suggestion and for them it looks like a good choice. However, they noticed that its a Current Feedback Amplifier and wanted to know reasoning behind a CFA suggestion?

    Thanks and regards,

    Art

  • 0 in reply to Art Mecina
    Guru 48395 points

    No reasoning, it is just that the CFA apps often require a lot of output power and that is what you are asking for. Also, for lower supplies, the OPA2677 dual puts out a lot of current for another CFA. 

  • 0 in reply to Art Mecina
    TI__Expert 3620 points

    Hi Art,

    Michael is right on point, might want to check out that OPA2677 he suggested as well.

    Best,

    Sam