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1~3 watt 3~300kHz ampilfier 10 ohm load low distortion amplifier

Albert Lu1
Intellectual 520 points
Other Parts Discussed in Thread: OPA564

Hi All,

I'm looking for a low frequency amplifier that's capable of driving 1+ watt into a coil antenna around audio frequencies, and if possible, into 100~300KHz . 2nd order harmonic needs to be better than 80db, since I'm actually looking for the harmonics produced by the sensor.

I know there are tons of audio amps out there capable at low frequencies, but they always end up using THD instead of IIP.. which is pretty frustrating.

  • 0
    TI__Guru* 93105 points

    Hi,

    Our power operational amplifiers may not have high enough bandwidth to assure that the 2nd harmonic will be down 80 dB, at 100 to 300 kHz. The best candidate would be the OPA564, but its open-loop gain looks to be only about 30 to 32 dB at 300 kHz. Even if the closed-loop gain is set to 1 V/V, there just may not be enough loop gain to keep the distortion low. And then there is the issue of the load impedance which can highly affect the distortion produced by the amplifier. I suspect you may get the best results using a wideband operational amplifier, followed by a discrete transistor output stage.

    Regards, Thomas

    PA - Linear Applications Engineering