Hi, I have a question about OPAMP input differential voltage.

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Hi, I was studying OPAMP distortion from TI precision lab.

In the above picture, one of distortion source of OPAMP is 'input differential voltage.'

Does 'input differential voltage' same with 'input offset voltage'?

Thanks,

Yun

1 Reply

  • Hello Yunsik,

    The op amp circuit above is a non-inverting amplifier circuit. The non-inverting input sees the full voltage range that the input signal source produces. The op amp common-mode voltage (VCM) is equal to the source voltage level. The inverting input will track the non-inverting input's VCM level, but they will be separated in voltage by the op amp's voltage offset plus a small differential voltage whose level is a function of the amplifier circuit's loop gain.

    Low level distortion occurs as the Vcm level applied to the op amp input changes. It tends to require a large Vcm change for the distortion to be measurable. This distortion is the result of a non-linear change in the common-mode capacitance (CCM) as the voltage across the capacitance changes. Newer TI audio op amps are designed to minimize this type of distortion as well as other types of distortion.

    Regards, Thomas

    Precision Amplifiers Applications Engineering