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

Department of Solid-State Electronics, Technische Universitt Ilmenau, D-98684 Ilmenau, Germany

Toufik.Sadi@tu-ilmenau.deMOS-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 SummaryOutlineMOS-AK/GSA Workshop Paris - 7th & 8th April 2011

Framework: Within the COMON (COmpact MOdelling Network) project funded by the European Union

Aim: 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 HEMTsMOS-AK/GSA Workshop Paris - 7th & 8th April 2011

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 modelsNon-linear HEMT Models Design of modern microwave circuits and systems Minimization of Intermodulation DistortionMotivationMOS-AK/GSA Workshop Paris - 7th & 8th April 2011

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

Intermodulation in HEMTsTwo-tone Input Input with two frequency components f1 and f2Signal (Intermodulation ) components at new frequencies are generatedExample: 3rd order transfer characteristicsMOS-AK/GSA Workshop Paris - 7th & 8th April 2011

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

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

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 extractionSuitability for intermodulation distortion studies Angelov et al, IEEE Trans. MTT, vol. 40, p. 2258, 1992MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

Chalmers Model for HEMTs Limitations 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 IPKImproved model to provide much more independent control of the shape of the current and transconductance curves while maintaining the principal advantages of the Chalmers modelAngelov et al, IEEE Trans. MTT, vol. 40, p. 2258, 1992MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

New Current-Voltage Model (1)f(VGS)f(VDS)MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

New Current-Voltage Model (2)MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

New Current-Voltage Model (3)EC: more flexibility for I-V curves & derivativesVTN: fine-tuning parametersFager 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)MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

I-V Curves0.25m 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, 2004VGS : -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 DCMOS-AK/GSA Workshop Paris - 7th & 8th April 2011

Volterra Series AnalysisTwo-tone excitation input 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 pointsModeling the contribution of the current source to non-linearitiesMOS-AK/GSA Workshop Paris - 7th & 8th April 2011

Accomplished Work (5)

IMD analysis in high-power GaN HEMTs and LDMOSFETsGaN HEMT (Cabral et al., MTTS 2004)LDMOS FET (Fager et al., IEEE MTT, p. 2834, 2002)MOS-AK/GSA Workshop Paris - 7th & 8th April 2011

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 devicesAcknowledgmentsThis work is funded by the European Union, in the framework of the COMON project.MOS-AK/GSA Workshop Paris - 7th & 8th April 2011