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Harmonic Spec THS4521

Ronald Dekker
Prodigy 90 points

Other Parts Discussed in Thread: THS4521

Hello,

 

I am looking at the datasheet of the THS4521.

At the harmonic specs of f =1KHz Vout 1Vrms G=1 there is an note 2( Not directly measureable; calculated using noise gain of 101)

Can somebody explane this note to me.

 

Thanks in advance

  • 0
    Genius 5430 points

    Ronald;

    This means that in a gain of 1V/V, the harmonic distortion was so low that it could not be measured. By placing it in a high noise gain, the amplifier's negative feedback was reduced and the distortion was then high enough to measure.

  • 0
    TI__Genius 13335 points

    Ron,

    That note exists to show that at low frequencies the harmonic performance starts to become dominated by the noise floor of the measuring equipment. At 1kHz, the harmonic performance of the THS4521 was actually much better than what the equipment can measure. In fact, the performance measured was nearly the same with and without the amplifier. Therefore, we can't directly measure the performance at 1kHz, but we can estimate the value by placing the THS4521 in a large noise gain and use the reduction in loop gain correction.

    Regards,
    Luke

  • 0 in reply to Luke LaPointe
    TI__Genius 13335 points

    Thanks Neil,

    I did not see your post to this.

    Regards,
    Luke