[sdiy] ultra low noise op amps

[John Luciani]

On 9/18/07, John Mahoney <jmahoney at gate.net> wrote:
> Looking for the lowest distortion and noise? National Semi has some
> fairly new op amps (supposedly announced on July 23) with a mere
> 0.00003% THD+noise, making for a dynamic range of 130dB.
>
> Some additional specs:
>         DC Gain Linearity Error: 0.000009% (quite good, no?)
>         Input Offset Voltage  0.1mV (typ.)
>         Input Bias Current  10nA (typ.)
>
> That last number doesn't match the LT1013's "Guaranteed Offset
> Current" of 0.8nA. Am I comparing apples to apples?

IIRC the input bias current is the maximum current that flows into (or out of)
either the +IN or -IN pin. The input offset current is the difference
between the
two bias currents.

The offset current for the LME49740 is 65nA max (11nA typ).

You alse need to verify the test conditions for the bias and offset
current tests to
make sure that your are comparing apples to apples.

(* jcl *)

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