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LMH6551: THD or distortion rate

Hirotaka Matsumoto
Guru 27575 points
Part Number: LMH6551

Hi all

Would you mind if we asked LMH6551?

Does this device have THD or distortion rate?
We understand that audio OPAMPs have THD or distortion rate, however general OP AMPs and high speed OP AMPs aren't specified specification.

As the background of this question, our customer use this device with following conditions;

<Condition>
-Output : Differential output
-Output impedance(|Z|) : 200ohm 
-Voltage range : 0-5V
-VCM(Center output voltage) : 2.5V
-Vsw : 1Vpp
-> In case of single end output : 1Vpp
-> In case of differential output : 2Vpp

The customer would like to know  THD or distortion rate with both outputs conditions.


Kind regards,

Hirotaka Matsumoto

  • +1
    Guru 140200 points

    Hi HIrotaka,

    the datasheet of LMH6551 contains lots of distortion specifications. But the distortion is not given in the unit "%" but in the unit "dBc".

    Kai

  • +1
    TI__Mastermind 24325 points

    Hello Matsumoto-san,

       Agreed with Kai. Our high speed amplifiers do characterize/measure for distortion specifications, but not in as many configurations as done for our audio amplifier portfolio. LMH6551 distortion specifications can be found on page 6, 7, 10, and 11 of the device datasheet. 

       If above conditions are applied for an amplifier with a +5V single supply configuration:

        The Figure is for RL of 500Ohms, therefore, RL of 100Ohms will lead to lower distortion performance. However, this will also depend on gain and frequency, and above figure was characterized with an amplifier at unity gain at 5MHz. For more distortion performance over frequency, the datasheet has more information shown on Figures 9 to 13. 

    Thank you,
    Sima