Q:

Noise calculation for ADA4528

I thought I got familiar with noise calculations and RMS nv/rthz conversions, hence I went forward to test my understanding.
I am comparing some opamps based on their noise levels.
So I wanted peak to peak noise, for an opamp ADA4528 at 0.1 to 10 Hz band, and they quoted the same in datasheet as 99 nVpp. so I wanted to verify this and I went on to their noise density graph at page 18. which shows noise density to be 6nV/rtHz. at 0.1 to 10 Hz and its nice rectangle so I went on and multiplied 6 nV/rtHz with sqrt(9.9 Hz) to get 18nVrms. so to get output noise I multiplied it with gain (100) and everything shattered. :P
Where am I going wrong. in datasheet it says 99nvpp at gain of 100 and I get nowhere near it by calculation.
Please help.

A:

I think, what you have overlooked is, that when you basicly multiply the 10Hz bandwidth with the 6nV, you get an rms voltage. 
According to Paul Horowitz, experiments have shown, that the peak-peak-voltage is about 6 times the rms-voltage. So when you mulitply the 18nVrms by 6, you get about 99nVpp. 

