Model Parameters
Curtice GaAs MESFET model parameters are summarized in the following table. Table 89 lists the parameters with descriptions and default values. Setup attributes are listed in Table 90.
Table 88 Summary of Curtice GaAs MESFET Model Parameters
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Controlling Model Parameters
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Inductance and Resistance
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LD, LG, LS, RD, RG, RS
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Diode
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IS, VBI, N
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Threshold
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Level 1: VTO
Level 2: A0, A1, A2, A3
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Linear and Saturation
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Level 1: BETA, LAMBDA, ALPHA
Level 2: BETA, GAMMA
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Capacitance and AC
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CGDO, CGSO, CDS, RDSO, RIN, A5
optionally: CGD, CGS, TAU
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Table 89 Curtice GaAs MESFET Model Parameters
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Inductance and Resistance Parameters
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LD
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Drain Inductance. Specifies external drain inductance.
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0 Henry
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LG
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Gate Inductance. Specifies external gate inductance.
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0 Henry
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LS
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Source Inductance. Specifies external source inductance.
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0 Henry
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RD
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Drain Resistance. Specifies external drain resistance.
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0 Ohm
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RG
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Gate Resistance. Specifies external gate resistance.
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0 Ohm
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RS
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Source Resistance. Specifies external source resistance.
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0 Ohm
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Diode Parameters
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IS
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Diode Reverse Saturation Current. Models gate-drain and gate-source current.
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1 x 10-14 Amp
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VBI
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Gate Junction Potential. Models built-in potentials of gate-source and gate-drain regions.
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0.8 Volt
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N
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Diode Emission Coefficient. Models emission coefficient of an ideal diode. In TECAP and some simulators this parameter is called XN.
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1.0
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XTI
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Diode Saturation Current. Temperature Coefficient.
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3.0
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EG
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Diode Energy Gap
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1.11 EV
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DC Parameters: Level 1 (Quadratic)
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ALPHA
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Coefficient of VDS. It is the Vds coefficient in the tanh function of the quadratic equation.
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2.0 V-1
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BETA
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Transconductance Parameter. Defines transconductance in the saturation or linear operating regions. Same as JFET model. In TECAP and some simulators this parameter is called BETA1 for level 1, and BETA2 for level 2.
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1 x 10-4 AÞV-2
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LAMBDA
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Channel Length Modulation Parameter. Models the finite output conductance of a MESFET in the saturation region.
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0V-1
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VTO
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Threshold Voltage. Models gate turn-on voltage. Same as JFET model.
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0V
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DC Parameters: Level 2 (Cubic)
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GAMMA
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Coefficient of VDS. It is the Vds coefficient in the tanh function of the cubic equation.
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0.5V-1
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BETA
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Coefficient for pinchoff. Defines change with respect to VDS In TECAP and some simulators this parameter is called BETA1 for level 1, and BETA2 for level 2.
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1 x 10-4 A·V-1
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A0
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0-Order Coefficient for V1 in IDS cubic equation.
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1 x 10-2 Amp
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A1
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1st-Order Coefficient for V1 in IDS cubic equation.
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1 x 10-3 A·V-1
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A2
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2nd-Order Coefficient for V1 in IDS cubic equation.
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-1 x 10-3 A·V-2
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A3
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3rd-Order Coefficient for V1 in IDS cubic equation.
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-1 x 10-4 A·V-3
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VDSO
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Value of VDS at which A0 through A3 are determined
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5.0 Volt
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RDSO
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Internal Resistance. Drain to Source AC Leakage Path. In TECAP and some simulators this parameter is called RDS
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1 x 1012 Ohm
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VDSDC
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VDS Bias at which RDSO, CGD and CGS are determined
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0V
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AC and Other Common Parameters
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A5
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Proportionality Constant. Varies TAU as a function of VDS. Use TAU for constant time delay or A5 to vary delay as a function of VDS.
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0 S·V-1
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TAU
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Internal Time Delay. Constant internal time delay from drain to source.
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0 Sec
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VBR
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Reverse Breakdown Voltage. From gate to drain.
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100V
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RIN
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Series Resistance. In series with CGS. Used to model the change in input impedance with frequency.
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0 Ohm
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Piecewise Linear Current Parameters
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R1
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Approximate Breakdown Resistance. R1 is the breakdown resistance from drain to gate.
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0 Ohm
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R2
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Resistance Relating Breakdown Voltage. R2 is the resistance relating breakdown voltage to channel current.
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0 Ohm
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RF
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Effective Value. RF if the effective value of forward-bias resistance gate to source.
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0 Ohm
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Constant Capacitance Parameters
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CGD
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Gate to Drain Capacitance
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0 Farad
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CGS
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Gate to Source Capacitance
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0 Farad
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CDS
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Drain to Source Capacitance
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0 Farad
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FC
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Coefficient for forward-bias depletion capacitance
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0.5
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Non-Linear Capacitance Parameters
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CGDO
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Zero bias Junction Capacitance. Non-linear Gate to Drain Capacitance at zero DC bias.
|
0 Farad
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CGSO
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Zero bias Junction Capacitance. Non-linear Gate to Source Capacitance at zero DC bias.
|
0 Farad
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Table 90 Setup Attributes for the Curtice GaAs Model
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ac/
s_at_f
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vg, vd, vs, freq
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s
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extract_L_and_R
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GAASAC_l_and_r
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LD, LG, LS, RD, RG, RS
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dc/
igvg_0v[sd]
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vg, v[sd]
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ig
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extract
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GAASDC_lev1
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VBI, IS, N
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optim1
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Optimize
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VBI, IS, N
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dc/
idvg_hi_vd
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vg, vd, vs
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id, ig
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extract
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GAASDC_cur1
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Level 1: VTO
Level 2: A0, A1, A2, A3
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optim
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Optimize
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Level 1: VTO
Level 2: A0, A1, A2, A3
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dc
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vd, vg, vs
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id, ig
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extract
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GAASDC_cur2
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Level 1: BETA, ALPHA, LAMBDA
Level 2: BETA, GAMMA
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optim
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Optimize
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Level 1: BETA, ALPHA, LAMBDA
Level 2: BETA, GAMMA
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ac
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vg, vd, vs, freq
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s
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extract_CV
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GAASC_cur
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CGDO, CGSO, CDS, RDSO, RIN, A5
optionally: CGS, CGD,TAU
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