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Suggestion of Op Amp

Hau Ran Cheong
Prodigy 20 points
Other Parts Discussed in Thread: LM7171, THS3095, THS3091

Hi, I'm a university student currently working on wireless power transfer system.

Does any Op Amp when design as an inverting or non inverting amplifier can support up to Below criteria?

Sinusoidal Signal 

Input signal frequency = 25MHz 

input signal Vpp = 10Vpp

Output signal Vpp = 26-30Vpp with same frequency as input signal.

Can anyone suggest me an appropriate Op Amp can be used to amplifier the signal mentioned?

  • 0
    TI__Prodigy 610 points

    Hi Hau,

    Wireless power transfer sounds like a fun project, and we are happy to help you select an amplifier.

    Based on your requirements, you will need an amplifier with a slew rate of minimum SR=Vo*2*pi*f=15*2*pi*25=2400V/us.. These amplifiers will all have a gain bandwidth product (GBWP) of more than 50MHz. All TI amplifiers with GBWP>50MHz are found among the High Speed Amplifiers.

    It would be helpful to know how many channels you need and what your supply voltage is (it must be more than +/-15V). You might want to consider the LM7171. It should have more than enough bandwidth and slew rate to support your requirements and has a total supply voltage of 33V. Please check the datasheets to ensure that you stay within the specifications of the amplifier. Finally, ensure that the circuit is stable; particularly if you have a capacitive load or if you use large feedback resistors (above some hundreds of Ohms) in the inverting configuration. Stability concepts are very well explained in the TI Precision Labs.

    Good luck,

    Gustaf Falk Olson

  • 0 in reply to Gustaf Falk Olson58
    Prodigy 20 points

    Hi Gustaf Falk Olson,

    Thanks for your suggestion.

    Previously I've tried with LM7171. The GBWP is more than 100MHz, however the signal output is distorted due to the limited slew rate.

    The output shall be around 26-30Vpp. But the distortion made it became 17Vpp only.

    The supply voltage is +/- 15V and the signal input is as mentioned by the question.

    And I have followed exactly the connection of inverting amplifier in datasheet.

    Thanks for your replied Gustaf Falk Olson. Much appreciated.

  • 0 in reply to Hau Ran Cheong
    TI__Genius 15975 points
    Hi Hau,

    You might take a look at the THS3091 or THS3095 which could possibly make it to 26Vpp using +/-16V and lighter load condition. 30Vpp might be challenging for the high speed parts as you might need around +/-36V supply with > 2400V/us slew rate at 25MHz. We currently don't have such a part in our portfolio.

    Best Regards,
    Rohit