Flicker Noise Extraction for Scalable MOS Simulation Models · Page 18 Summary Together with the...

Flicker Noise Extraction forScalable MOS Simulation Models

Dr. Thomas Gneiting

AdMOS GmbH

[email protected]

Content

Flicker noise equations in modern MOS models

Noise simulation in different simulators

Steps in parameter extraction using a PSP example

Problems to be solved

Summary

Common Flicker NoiseModels

100 101 102 103 104 105

10-17

10-18

10-19

10-20

10-21

10-22

10-23

10-24

f [Hz]

Sid [A²/Hz]

Frequencyexponent

Start ofthermal noise

100 101 102 103 104 105

10-17

10-18

10-19

10-20

10-21

10-22

10-23

10-24

f [Hz]

Sid [A²/Hz]

DC biasdependency

+ Dimension dependency

The most MOS simulation models provide the following 2 principaldegrees of freedom to adjust the flicker noise behavior.

BSIM3 Flicker Noise

EFeffOX

AF

DSid

fLC

IKFfS

2)(

*

2

82

2

22

14

14

82

2

10*2

2102

102log

10*2)(

NN

NNOICNNOIBNOIA

fLINTNOILW

LITk

NNNOIC

NNNOIBN

NNOIA

fALINTNOILC

IqTkfS

l

ll

EFeffeff

CLMDSB

lOlO

l

O

EFbulkeffoxe

DSeffB

id

36

2

'

'

104)(,)(

EFeffeff

DStmwi

wimitli

wimitliid

fLW

IVNOIAfS

SS

SSfS

NOIMOD=1,4,5

NOIMOD=2,3,6

Vgs>Vth+0.1:

Vgs<Vth+0.1:

“classic” SPICE model

BSIM3 model

BSIM4 Flicker Noise

EFeffOX

AF

DSid

fLC

IKFS

2

2*

2

102

2

22

*

*

102

2

,

10*2

2log

10*2)(

NN

NNOICNNOIBNOIA

fLINTNOILW

LITk

NNNOIC

NNNOIBNN

NNNOIA

fALINTNOILC

IqTkfS

l

ll

EFeffeff

CLMDSB

lOlO

l

O

EFbulkeffoxe

DSeffB

invid

102*

2

,

,,

,,

10)(,

)()(

)()()(

NfLW

ITkNOIAfS

fSfS

fSfSfS

EFeffeff

DSBsubVtid

subVtidinvid

subVtidinvid

id

FNOIMOD=0

FNOIMOD=1

Inversion:

SubVth:

“classic” SPICE model

PSP Flicker Noise

NNNNFCNFB

NN

NNNNFCNNFBNFA

NGCf

IqfS

m

m

m

vsatox

DSTfl

**

*

*2**

*

2

2

2/

2/ln)(

EE

ENEN

EE

ENEN

EE

ENEN

LW

LWNFCLWNVC

LW

LWNFBLWNFB

LW

LWNFALWNFA

Local model:

Scalingequation:

Fixed frequency exponent of 1!

Noise in ADS

define noise_circ (D G OUT)Flicker_Noise:MAIN D1 G 0 0 \L=10u W=10u Mult=1;; sense the noise currentR:Rdummy D D1 R=1m Noise=no;;convert noise current into anidentical voltageZ_Port:v D1 D OUT 0 Z[2,1]=1R:Raux OUT 0 R=1k Noise=no;end noise_circ

Noise in Spice, HSPICE

.subckt noise_circ 1 2 5 7MAIN 9 6 0 0 Flicker_Noise+ L=10u W=10u NF=1L2 6 2 1000000C2 5 6 1000000H1 8 0 V1 1R1 7 8 1e-4V1 1 9 0.ends

Content

Flicker noise equations in modern MOS models

Noise simulation in different simulators

Steps in parameter extraction using a PSP example Measurement (see paper from IHP, Falk Korndörfer)

Determination of the frequency exponent

Determination of bias dependency

Extraction of parameters for scalable noise models shown withan example using the PSP model


Summary

*) Based on the work of Knoblinger, Grabinski, Sischka

*)

Frequency Exponent (1)

100 101 102 103 104 105

10-17

10-18

10-19

10-20

10-21

10-22

10-23

10-24

f [Hz]

Sid [A²/Hz]

EF

If the model provides afrequency exponent, it can bederived from the slope of themeasured curves in logarithmicrepresentation:(Example for SPICE model, the othermodels behave similar)

xmcy

fEFconfS

fconfS

fLC

IKFfS

id

EFid

EFeffOX

AF

DSid

loglog)(log

)(

)(2

Frequency Exponent (2)

In the real world:

EF must fitseveral deviceswith diff. L, Wsimultaneously

Take intoaccount onlyparts of thecurves due tomeasurementrestrictions.

DC Bias dependency (1)

100 101 102 103 104 105

10-17

10-18

10-19

10-20

10-21

10-22

10-23

10-24

f [Hz]

Sid [A²/Hz]

Sid [A²/Hz]

0 1 2 3 4

10-17

10-18

10-19

10-20

10-21

Vg[V]

Once the slope is given, the noise values at 1Hz can be determined byextrapolating the measured curve to 1Hz.

EFeffOX

AF

DSid

fLC

IKFfS

2)(

=1 at 1Hz

(Example for SPICE model, the othermodels behave similar)

DC Bias dependency (2)

3 Steps:

Select range ofcurves todetermine slope

Make curvesslopeless

Apply linearfitting to theselected range ofthe curve anddetermine cross-point at 1Hz

Parameter Extraction – PSP (1)

Sid(f=1Hz)@ diff Vg,Vd, L, W

SolverSfl(1Hz)=f(Parameter,Dimensions,DC Bias)

Iterative Solutionusing a modifiedLevenberg-Marquardt algorithm

Noise parameters

PSP:PSP1020 Par.L, W, MULTVG, VD

PSP:NFALW, NFBLW,NFCLW


1. Simulation withdefault valuesof NFALW,NFBLW,NFCLW

2. Performextraction inca. 1s andrepeatsimulation

Example parameterextraction process:


Final resultfor 4differenttransistordimensions.


The scalability of the simulation models isstill not good enough.

The PSP scaling equation:

does not allow to modify parametersindependently for L and W. Actually, onlythe product L·W is taken into account.

EE

ENEN

EE

ENEN

EE

ENEN

LW

LWNFCLWNVC

LW

LWNFBLWNFB

LW

LWNFALWNFA

Fitting for smalldevice cannot beimproved in this areawithout the distortionof the other devices.

Summary

Together with the measurement of flicker noise ( presentedby Falk Korndörfer, IHP), the shown extraction strategy isthe basis of a complete noise modeling method.

The very effective simultaneous extraction of flicker noiseparameters for different devices with different dimensions isthe key improvement of this tool.

The shown methodology for PSP was implemented forcommon MOS models (BSIM3, BSIM4) and can be easilyextended to other models like HiSIM2 etc.

The co-operation between IHP and AdMOS resulted in acommercial available Flicker Noise Modeling Tool. Fordetails, please see:www.admos.de Products Flicker Noise System

Flicker Noise Extraction for Scalable MOS Simulation Models · Page 18 Summary Together with the...

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