Do n+ / p+ diffusion resistors exhibit flicker noise?

[diarmuid]

Hello,

I know that poly resistors have flicker noise but do diff resistors also?

Thanks,

Diarmuid

 

[erikl]

Yes, any resistor.

 

[diarmuid]

Really. While I have found many articles documenting flicker noise in poly resistors, I havent seen so many for flicker noise in diffusion resistors.

Why is this? Is it that flicker noise in diffusion resistors is perhaps not that big a component of the overall noise or something?

Thanks,

 

[erikl]

Is it that flicker noise in diffusion resistors is perhaps not that big a component of the overall noise or something?

Flicker noise emerges from interferences of current flow at any boundary interfaces (worst in MOS channels). Diffusion resistors show more interface area (actually the whole reverse-biased silicon junction around it) than poly resistors, so I'd expect they'd exhibit relatively more flicker noise than the latter ones - although I have no docu to prove my opinion.

A G00GLE search on flicker noise of diffused resistors indeed reveals some - more or less - theoretical papers on that - amongst others a nice overview on 1/f noise, but I didn't find anything concrete to differentiate between poly and diffused resistors. Also, the foundry docs don't give corresponding values, unfortunately.

 

[diarmuid]

Thanks Erikl for that. Interesting the lack of work done on 1/f noise for diffusion resistors. Certainly be a topic well worth researching.