How to choose frequency to specify the amplifier noise

[artho]

Hi,

I would like to know how i choose the frequency to specify the amplifier noise. Some works take the worst value of the noise curve as a constraint for a amplifier design, but in datesheets(example: http://cds.linear.com/docs/en/datasheet/624012fe.pdf at 1 kHz) this value is taken by a specific frequency.
My doubt is, i have to take the first value at low frequency, or i have to take the value where the noise is almost linear?
Thanks.

 

[chuckey]

the LF noise is due to "flicker" which is a different effect from wide band thermal noise, hence two figures for designers to use, depending on their application.
Frank

 

[godfreyl]

How you specify the noise depends on the application. For audio circuits, it's common to specify the total noise over the audio band (20Hz - 20KHz).