Modeling Intermodulation Distortion in HEMT and LDMOS Devices Using a New Empirical Non-Linear...

Modeling Intermodulation Distortion in HEMT and LDMOS Devices Using a New Empirical Non-Linear Compact Model

Toufik Sadi and Frank SchwierzDepartment of Solid-State Electronics,

Technische Universität Ilmenau, D-98684 Ilmenau, Germany

[email protected]

MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

Objectives Motivation Non-linearities in semiconductor devices Non-linear FET models Compact modeling of III-V HEMTs and LDMOSFETs

Motivation New in-house model Validation

Summary

Outline


Framework: Within the COMON (COmpact MOdelling Network) project funded by the European UnionAim: Development of improved universal HEMT models Objectives:

Efficient current-voltage, charge and noise models GaAs, GaN HEMTs and other high-power devices

Focus: Non-Linearities in HEMTs Intermodulation distortion (IMD)

Included Effects: Self-heating; frequency dispersion; etc..

Compact Modeling of III-V HEMTs


Current-Voltage (I-V) Model Accurate modeling of I-V characteristics and derivatives

Inclusion of electrothermal & frequency dispersion effects Applicable to GaAs and GaN HEMTs, and to Si LDMOS FETs Effective parameter extraction and fitting routines Modeling of IMD figures of merit using Volterra series analysis

Charge (C-V) Model Correct modeling of C-V characteristics is sufficient

Using simple/existing models

Non-linear HEMT Models Design of modern microwave circuits and systems

Minimization of Intermodulation Distortion

Motivation


Non-Linearities in Electron Devices

Non-linear I-V characteristics Distortion of the output signal shape New frequency components appear

2nd order: 2xf 3rd order: 2xf, 3xf nth order: 2xf, 3xf,…,nxf

0.0 0.5 1.0 1.5 2.0-15

-10

-5

0

5

10

15

Dra

in c

urre

nt (a

.u.)

Time

0.0 0.5 1.0 1.5 2.0-20

-10

0

10

20

30

40

Out

put (

a.u.

)

Time

Output Signal

Linear output Non-linear output

Almost everything in semiconductor electronics is nonlinear !!!

cos( )GS PV V t

1( )

d GSI t K V

2

1 2

3 4 5

3 4 5

( )

d GS GS

GS GS GS

I t K V K V

K V K V K V


Intermodulation in HEMTs

Two-tone Input Input with two frequency components f1 and f2

Signal (Intermodulation ) components at new frequencies are generated

1 2 1 1 2 2

cos cos inV t V t V t A t A t

Example: 3rd order transfer characteristics

1 2 1 2

1 2 1 2

2

1 2

1 2

1 2

th

st

nd

1

rd

0 :

1 :

2 :

( ), ( )

(2 ), (2 ),

3 :

,

2 , 2 ,

(2 ), (

3 , 3 ,

2

out

f f

DC

f f

f f

f f

V

f f

f f f f

f

t

f

2 1)

f f


Compact Models for III-V FETs

Physics-based Analysis of effect of physical parameters (gate length, mobility, etc…) No parameter optimization Rigorous mathematical formula Technology-dependent Discontinuous (using of conditional functions)

Table-based Storing parameters at several biases in a table No parameter optimization Technology-dependent Discontinuities in the model elements or their derivatives

Empirical Simple Flexible Continuous Technology-independent Good model formulation Parameter optimization


Non-Linear Empirical III-V FET Models

Curtice Model (1980) Quadratic/cubic dependence of ID on VGS

First empirical time-domain simulation model Tajima Model (1981) Exponential dependence of ID on VDS and VGS

First empirical frequency-domain simulation model Materka Model (1985) Quadratic/hyperbolic dependence of ID on VGS

Including drain-bias dependent pinch-off potential Statz Model (1987) Hyperbolic/cubic dependence of ID on VGS/VDS

Temperature scalability TOM Model(s) (1990) Exponential/cubic dependence of ID on VGS/VDS

Spatial/temperature scalability ADS EEFET/EEHEMT Model(s) (1993) Rigorous formula

Charge-based C-V model Chalmers Model (1992) Hyperbolic dependence of ID on VGS/VDS

First to provide a good fit for transconductance and derivatives Auriga Model (2004) Enhanced version of the Chalmers model


Chalmers Model for HEMTs – Advantages

Infinitely differentiable hyperbolic functions Inherent reconstruction of the bell-shape of Gm(VGS) for GaAs HEMTs

Reliable modeling of the higher order derivatives of Gm(VGS) curves

Continuity – no conditional functions Possibility of readily including several effects, such as temperature effects, frequency dispersion, and soft-breakdown Simple procedure for parameter extraction

Suitability for intermodulation distortion studies Angelov et al, IEEE Trans. MTT, vol. 40, p. 2258, 1992


Chalmers Model for HEMTs – Limitations

max 1 max

1

Drain current at (at ) /

(

[1 tanh{ ( )}] tanh( )(

1

) ( )

)

PKPK GS PK

ni

GS n GS PK

D PK GS DS DS

i

gm gm II V V P

V P V

I I V V V

V

Limited suitability to model high-power devices and new structures such as GaN HEMTs and LDMOSFETs (Fager et al., IEEE MTT, p. 2834, 2002; Cabral et al., MTTS 2004)

Saturation current (ISAT) is limited to 2 IPK

Improved model to provide much more independent control of the shape of the current and transconductance curves while maintaining the principal advantages of the Chalmers model

Angelov et al, IEEE Trans. MTT, vol. 40, p. 2258, 1992


New Current-Voltage Model (1)

( )

( )

( ) (1 tanh

ln(1 exp{ ( ) / })

ln(1 exp{

{ ( ) }) 0

( ) ( tanh{ ( ) }

( / )

0

) }

)

[ ( ) ( ) ] tanh( )(1 )

GS PK

GS P

GS GS

GS G

K

S

GS PK GS

GS PK GSSAT

GS GS DS DS

f V V

f V V

V V

V V

F V I f V

EC g EC

EC g EC

F V I I f V

I F V F V V V

f(VGS) f(VDS)


New Current-Voltage Model (2)

1 2 1 2

1 2 1 2

2 2 2 2

2 2 2 2

1

1

( )

( )

( ) (

( ) (

{

{ .

( )

( )

) }

) }PK

SAT PK

TN TN TN TN

TN TN TN TN

GS n GS

GS n GS

GSN GS P

GS

GS

K

ni

i

ni

GSP

GSN GSN

G S

i

SP G P

I

I I

h V V V

h V V V

V

g V P h V

g V P h

V

V

V V

V V V V

V V V V


New Current-Voltage Model (3)EC: more flexibility for I-V curves & derivativesISAT: IMAX = 2 IPK

VTN: fine-tuning parameters

Fager et al., IEEE MTT, p. 2834, 2002MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

I-V Model Advantages

Continuous – closed-form expression Accurate modeling of I-V characteristics and derivatives

Simple parameter extraction & fitting procedureApplicable to GaAs, GaN HEMTs; LDMOS FETs;

LDMOS FET (Fager et al., IEEE MTT, p. 2834, 2002)GaN HEMT (Cabral et al., MTTS 2004)


I-V Curves

0.25m gate-length GaAs pHEMT [1]

[1] K. Koh et al, in Proc. IEEE IMS, p. 467, 2003 [3] C. Fager et al, IEEE Trans. MTT, vol. 50, p. 2834, 2002 [2] J.-W. Lee et al, IEEE Trans. MTT, vol. 52, p. 2, 2004

VGS : -1.2V to -0.4V — Step = 0.1V0.35m gate length GaN HEMT [2]

VGS : -4V to 0V — Step = 1VLDMOS FET from [3]

VGS : 3 and 5V

Pulsed (300K)

Static DC


Volterra Series Analysis

Two-tone excitation input – 1 2

cos( ) cos( )Vin Vs t t

Results are from the GaAs pHEMT *

*K. Koh et al, in Proc. IEEE IMS, p. 467, 2003

Pin = -20dBm, RL = RS = 50 OhmPlin, PIM2, PIM3: linear, 2nd and 3rd order powerIP2, IP3: 2nd and 3rd order interception points

Modeling the contribution of the current source to non-linearities


Accomplished Work (5) IMD analysis in high-power GaN HEMTs and LDMOSFETs

GaN HEMT (Cabral et al., MTTS 2004)

LDMOS FET (Fager et al., IEEE MTT, p. 2834, 2002)


Conclusions

New flexible empirical non-linear model Minimized parameter fitting Accurate calculation of higher-order derivatives Suitable for intermodulation distortion modeling Applicable to a wide range of devices

AcknowledgmentsThis work is funded by the European Union, in the framework of the COMON project.


Date post:	04-Jan-2016
Category:	Documents
Upload:	dortha-campbell
View:	223 times
Download:	3 times

Modeling Intermodulation Distortion in HEMT and LDMOS Devices Using a New Empirical Non-Linear...

Documents