TWO-PORT NETWORK

ADMITTANCE PARAMETERS
The admittance parameters describe the currents in terms of the voltages
The first subindex identifies
the output port. The second
the input port.
The network contains NO independent sources

LEARNING EXAMPLE
Find the admittance parameters for the network
Next we show one use of this model

An application of the admittance parameters
The model plus the conditions at the
ports are sufficient to determine the
other variables.
Determine the current through the
4 Ohm resistor

IMPEDANCE PARAMETERS
The network contains NO independent sources

LEARNING EXAMPLE
Find the Z parameters
Write the loop equations

LEARNING EXAMPLE
Use the Z parameters to find the current through the 4 Ohm
resistor
Output port constraint
Input port constraint

HYBRID PARAMETERS
The network contains NO independent sources
These parameters are very common in modeling transistors

LEARNING EXAMPLE
Find the hybrid parameters for the network

TRANSMISSION PARAMETERS
The network contains NO independent sources
ABCD parameters

LEARNING EXAMPLE
Determine the transmission parameters

PARAMETER CONVERSIONS
If all parameters exist, they can be related by conventional algebraic manipulations.
As an example consider the relationship between Z and Y parameters

INTERCONNECTION OF TWO-PORTS
Interconnections permit the description of complex systems in terms of simpler
components or subsystems
The basic interconnections to be considered are: parallel, series and cascade
PARALLEL: Voltages are the same.
Current of interconnection
is the sum of currents
The rules used to derive models
for interconnection assume that
each subsystem behaves in the
same manner before and after
the interconnection

Parallel Interconnection: Description Using Y Parameters

Series interconnection using Z parameters
SERIES: Currents are the same.
Voltage of interconnection is the sum
of voltages

Cascade connection using transmission parameters
Matrix multiplication does not commute.
Order of the interconnection is important
CASCADE:
Output of first subsystem
acts as input for the
second

LEARNING EXAMPLE
Find the Y parameters for the network

LEARNING EXAMPLE
Find the Z parameters of the network
Use direct method,
or given the Y parameters transform to Z
… or decompose the network in a series
connection of simpler networks