ABCD Parameters The ABCD parameters are a set of four parameters that characterize the behavior of a two-port network under steady-state conditions. They ar...
ABCD Parameters
The ABCD parameters are a set of four parameters that characterize the behavior of a two-port network under steady-state conditions. They are named after the four variables that describe the network's impedance:
Z is the magnitude of the complex impedance of the network. It is measured in ohms (Ω).
R is the magnitude of the real part of the impedance. It is also measured in ohms (Ω).
I is the magnitude of the imaginary part of the impedance. It is also measured in ohms (Ω).
θ is the phase angle of the impedance. It is measured in degrees (°).
The ABCD parameters are related by the following equations:
Z = √(R² + I²)
θ = arctan(I/R)
These equations can be used to calculate the ABCD parameters of a two-port network from its impedance.
Example:
Consider a resistor (R) connected in parallel with a capacitor (C) as shown below.
[R] --- [C]
The impedance of the network is:
Z = √(R² + 1/C²)
The ABCD parameters of the network are:
Z = √(R² + 1/C²)
R = R
I = 0
θ = arctan(0/R) = 90°
Therefore, the ABCD parameters of the network are:
Z = √(R² + 1/C²) = √(1² + 1/C²) = √(2/C²)
R = R = 1 Ω
I = 0
θ = 90°