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Design >> Analog Design >> Flicker Noise
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Message started by Vikram C on Mar 20^th, 2009, 4:29am

Title: Flicker Noise
Post by Vikram C on Mar 20^th, 2009, 4:29am

Hi Guys,

I am designing an amplifier which is limited by flicker noise. Usually people have been using higher technologies as 0.7um for it as flicker noise was lower there. I am planning to design it in 130nm. I want an idea of how flicker noise is dependent on :

1. Technology.

2. Bias : Strong inversion or weak inversion

Thanks

Title: Re: Flicker Noise
Post by indysjl on Mar 20^th, 2009, 11:35am

Hello Vikram,

I don't know if this will help, but Razavi's CMOS design book cites Y. Tsividis, Operation and Modeling of the MOS Transistor, Second Ed. for more detailed expression for Flicker noise. Perhaps Tsividis sheds some light on Razavi's Process-Dependent Constant, K?

Title: Re: Flicker Noise
Post by raja.cedt on Mar 20^th, 2009, 10:12pm

hi,
first it is very difficult to model,even we can't believe spice in this regard..but up to some extent we can say with technology corner frequency will decreases.and i guess current flicker noise is independent on bias..where as voltage noise id depends on 1/gm..

but use spice for flicker noise don't believe expressions
Thanks,
Rajasekhar.

Title: Re: Flicker Noise
Post by Vikram C on Mar 21^st, 2009, 2:08am

@ indysji : yea i have been referring to them but they r dealing with the issues at a very basic level, u can say only an introduction.

@ raja.cedt: thanks for reply, but i think corner frequency has been increasing with technology scaling. Earlier it was in 10-100kHz , n nw in sum Mhz. Please tell me if i am missing sumthing. :-[

Do u have any idea if the models are based on number fluctuation or mobility fluctuation ?? And m still not sure hw Flicker Noise depends on bias as carrier conc. do change with bias and if we go by no. fluctuation, it should change with bias. But am very confused. :)

Title: Re: Flicker Noise
Post by loose-electron on Mar 22^nd, 2009, 4:51pm

as geometry scales down, the flicker noise bandwidth goes up

Fnoise is proportional to WL. now for the same size devices on different foundry processes, its difficult to say with authority, but for any semiconductor where the surface area of a junction structure becomes a larger proportion of the device, then the flicker noise should, in theory, go up.