Two Port Networks (1)

TWO PORT NETWORKSTWO PORT NETWORKS

Impedance Parameters [Z]Impedance Parameters [Z]

General equivalent circuitGeneral equivalent circuit

Admittance parameters [Y]Admittance parameters [Y]

Equivalent CircuitEquivalent Circuit

Problem2Problem2

HYBRID PARAMETRSHYBRID PARAMETRS

ExerciseExercise

Transmission or ABCD ParametersTransmission or ABCD Parameters

TWO-PORT NETWORK

Relationships between parameters

If a two-port network can be presented by different set of parameters, then there exists relationships between parameters.

e.g. relationships between z and y parameters:

2

1

2221

1211

2

1

I

I

zz

zz

V

V

2

1

1

2221

1211

2

1

V

V

zz

zz

I

I

We know that

2

1

2221

1211

2

1

V

V

yy

yy

I

I

Therefore

1

2221

1211

2221

1211

zz

zz

yy

yy

TWO-PORT NETWORK

Relationships between parameters

1

2221

1211

zz

zz

z

1121

1222

zz

zz

where 21122211z zzzz

Therefore, z

2211

zy

z

1212

zy

z

2121

zy

z

1122

zy

The conversion formulae can be obtained from the conversion table

e.g. on page 869 of Alexander/Sadiku

TWO-PORT NETWORK

Relationships between parameters

TWO-PORT NETWORK

Interconnection of networks

Complex large network can be modeled with interconnected two-port networks

• Simplify the analysis /synthesis

• Simplify the design

Parameters of interconnected two-port networks can be obtained easily: depending on the type of parameters and type of connections:

• Series: z parameters

• Parallel: y parameters

• Cascade: transmission parameters

TWO-PORT NETWORK

Interconnection of networks

Series: z parameters

[z] = [za] + [zb]

I1a

I1b

I2a

I2b

+V1b

+V1a

+V2a

+V2b

+

V1

+

V2

za

zb

z+V2

+V1

I1 I2

TWO-PORT NETWORK

Interconnection of networks

Parallel: y parameters

[y] = [ya] + [yb]

y+V2

+V1

I1 I2

I1a I2a

+V1b

+V1a

+V2a

+V2b

+V1

+V2

ya

yb

I1 I2

I1b I2b

TWO-PORT NETWORK

Interconnection of networks

Cascade: t parameters

[t] = [ta][tb]

t+V2

+V1

I1 -I2

I1a -I2a

+V1b

+V1a

+V2b

+V1

+V2

ta tb

I1 I1b -I2b

+V2a

-I2

Thank YouThank You