26-12-2012, 03:43 PM
An Introduction to S-parameters
An Introduction.ppt (Size: 2.82 MB / Downloads: 160)
S-parameters are a useful method for representing a circuit as a “black box”
The external behaviour of thisblack box can be predicted without any regard for the contents of the black box.
This black box could contain anything:a resistor, a transmission line or an integrated circuit.
A little math…
This is the matrix algebraic representationof 2 port S-parameters:
Some matrices are symmetrical. A symmetrical matrix has symmetry about the leading diagonal. In the case of a 2-port network, that means that S21 = S12 and interchanging the input and output ports does not change the transmission properties.
Larger networks:
The S-matrix for an n-port network contains n2 coefficients (S-parameters), each one representing a possible input-output path.
The number of rows and columns in an S-parameters matrix is equal to the number of ports.
The S-matrix for an n-port network contains n2 coefficients (S-parameters), each one representing a possible input-output path.
The number of rows and columns in an S-parameters matrix is equal to the number of ports.
For the S-parameter subscripts “ij”, “j” is the port that is excited (the input port) and “i” is the output port.