Pre-Amplifier + Latch Overall Input-Referred Offset

[Osawa_Odessa]

Hello,
Here is Pre-Amplifier + Latch Overall Input-Referred Offset:

Can anyone help me explain why these offset voltages are computed like that?
Why it is not V_offset preamp + V_offset latch/ Av?
Thanks!

 

[monsoon]

If you know the exact value of V_offset preamp and V_offset latch then you can use the formula V_offset preamp + V_offset latch/ Av. But these offsets are only know statistically. Further it is assumed that V_offset preamp and V_offset latch are uncorelated. Variance of sum of two uncorelated random variables is given by sum of the variances of the two random variables.

 

[Osawa_Odessa]

Thanks a lot, monsoon!
If you possible, please recommend me some material about the calculation or something relate to this.
And I would like to know why the result under the formula is more precise than the one obtain by using mean value?

 

[monsoon]

You refer to Razavi book. (chapter on noise and mismatch).
Its not "more" precise. Random variables are characterized by both mean and variance. You can also search about gaussian random variables.

 

[Osawa_Odessa]

Just curious, do you study about IC design? I want to be an IC designer and currently, I am learning about flash adc.