Why does the noise parameter KF of PMOS bigger than NMOS ?

[jake]

af kf noise

Hi, everyone
I am doing a simulation using TSMC 0.18, and I find that the parameter KF of PMOS is bigger than NMOS, why? Nomally, the noise of PMOS is less than NMOS.

.MODEL pch3 PMOS ( LMIN = '1.2E-06-dxl3'
+NOIMOD = 1 EF = 1.152 AF = 1.052 KF = 8.262E-28

.MODEL nch3 NMOS ( LMIN = '1.2E-06-dxl3'
+NOIMOD = 1 EF = 0.907 AF = 0.9065 KF = 8.704E-29

 

[hanm]

typical flicker noise coefficient

Hi jake;
af is Flicker noise exponent; kf is Flicker noise coefficient.
But flicker noise is not expressed straitfoward. Click the link for ditails:

**broken link removed**

 

[ezt]

why flicker noise is more in nmos than nmos

Hi.
Maybe I'm wrong, but I always thought that flicker noise is larger for PMOS devices than for NMOS. It's related to their physics. maybe that's because our process is usually n-well and this spec has something to do with doping.

EZT

 

[APPLESTREE]

why pmos has less flicker than nmos

I agreed with ezt. The carriers are holes in PMOS devices, and electrons in NMOS. Holes and electrons have different flick noise performance.

 

[jake]

why pmos is bigger than nmos

Hi jake;
af is Flicker noise exponent; kf is Flicker noise coefficient.
But flicker noise is not expressed straitfoward. Click the link for ditails:

h**p://www.ece.cmu.edu/~ee762/hspice-docs/html/hspice_and_qrg/hspice_2001_2-151.html#27580

thanks,
but for SPICE, we should use the formula when NlEV=0, right? When we assume the current Ids of the PMOS and NMOS are the same, Δaf=0.1455 in my case.so the Flicker nosie of PMOS is bigger than NMOS. In fact, in my simulation, the noise of NMOS is less than PMOS.

 

[yibinhsieh]

kf nmos

From physcis, the flicker noise in PMOS is less than the flicker noise in NMOS.


Yibin.

 

[qutang]

I think the hole is large than electrons.

 

[extraord]

Re: Why does the noise parameter KF of PMOS bigger than NMOS

I think the hole is much heavier than electron . So the noise should be less.
but if the pmos is in nwell, the surface of pmos is more coarse than nmos more doping IIIA and VA elements. So maybe Pmos's flicker noise is high

 

[richloo]

Flicker noise is caused by carriers randomly entering and leaving traps introduced by defects near the semiconductor surface.
So, PMOS have less flicker noise than NMOS since their majority carriers (holes) have less potential to be trapped in surface states.

 

[carlyou]

I agree with APPLESTREE

 

[wanily1983]

i think to the flicker noise pmos is less than nmos.

 

[Syukri]

Re: Why does the noise parameter KF of PMOS bigger than NMOS

Hi all,
Unlike thermal noise, the average power of flikcker noise cannot be predicted easily..In addition of trapping there are several factors generating lficker noise..

Ones that maybe easy to tell is that the "cleaness" of the oxide silicon interface. Doping level plays the role and thus it's varied for diffrent type of technology.

According to all the assumption above, diffrent technology uses diffrent doping and different design in order to get the best I/O transfers. These may cause the pmos kf bigger than nmos