**Part Number:**OPA627

Hi,

In TI Precision Lab Training about OP AMP noise part3,

voltage noise is divided into 1/f noise and broadband noise.

1/f noise is calculated with a complex equation.

Can we use the parameter offered in the datasheet "input voltage noise BW = 0.1 Hz to 10 Hz" to replace 1/f noise to calculate the total noise since 0.1Hz to 10Hz should be low frequency?

And for the resistor noise, I don't understand why we use R1//RF to calculate the noise.

What's wrong for calculating R1 noise, Rf noise independently and add them together?