vivkr
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Hi F117,
I am not sure if I understand your statement correctly, but here is an attempt to answer it:
1. Each trap operates independent of all the others. Hence, the overall effect is ensemble averaged. For instance, not all traps may be trapping and releasing the charges at the same time. The trap density is typically constant for a given process and so for moderate-large gate areas, increasing the overall gate area gradually increases number of traps. As the trap action can be considered as charge fluctuations in the channel, these can be referred back to the gate. In summary:
in^2 = K. (WL), where K is some constant vn^2 (at gate) = in^2/Cgate^2 => vn^2 = K/(W.L)
This is the principal reason why you have smaller 1/f voltage noise when the gate area is increased.
2. For very small gate area, there may be no trap. However, if there is a single trap for a very small gate, it causes more noise. For example, if the trap density is 2 traps/10 (um)^2, then the average number of traps for a 1 (um)^2 gate would be 0.2 . However, for any specific gate, you will either have a trap or not have a trap (assuming no more than 1 trap for a small gate). Thus, the noise from having a trap is higher than the average prediction. Note that the numbers quoted here are not realistic.
3. To remove 1/f noise, you need to use some form of autozeroing such as correlated double sampling or chopper stabilization, both of which will result in circuit overhead and more thermal noise.
You can find more information by searching for these topics in the previous posts.
Regards Vivek
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