> JFET model from Datasheet

JFET model from Datasheet

 

In this article we' ll see how to find the parameters used to describe the mathematical behaviour of JFET (Junction Field Effect Transistors).The syntax for the N-channel model is:

model ModelName NJF( par1=a par2=b.........parn=x)

while for the P-channel model is:

model ModelName PJF( par1=a par2=b.........parn=x)

Where par1 par2... parn are the parameters that allow us to model the equations of the JFET transistor.

The main parameters for modeling the JFET are listed below in this table:

 

Parameters

 

Description

Units

Default

AF

Flicker noise exponent

no unit dimension

1.0

ALPHA

Ionization coefficient

1/V

1e-006

BETA

Transconductance coefficient

A/V^2

0.0001

BETATCE

BETA exponential temperature coefficient

%/°C

-0.5

CGD

Zero-bias gate-drain p-n capacitance

F

1e-012

CGS

Zero-bias gate-source p-n capacitance

F

1e-012

FC

Forward-bias depletion capacitance coefficient

no unit dimension

0.5

IS

Gate p-n saturation current

A

1e-014

ISR

Gate p-n recombination current parameter

A

0

KF

Flicker noise coefficient

no unit dimension

1e-018

LAMBDA

Channel-length modulation

1/V

1e-006

M

Gate p-n grading coefficient

no unit dimension

0.5

N

Gate p-n emission coefficient

no unit dimension

1.0

NR

Emission coefficient for ISR

no unit dimension

2.0

PB

Gatep-n potential

V

1.0

RD

Drain ohmic resistance

Ohm

1.0

RS

Source ohmic resistance

Ohm

1.0

VK

Ionization knee voltage

V

1.0

VTO

Thresold voltage

V

-2.0

VTOTC

VTO temperature coefficient

V/°C

-0.0025

XTI

IS temperature coefficient

no unit dimension

3.0

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