Convert S-parameters of 2-port network to voltage or power-wave transfer function
Calculate the voltage transfer function of an S-parameter array.
ckt = read(rfckt.passive,'passive.s2p'); sparams = ckt.NetworkData.Data; tf = s2tf(sparams)
tf = 202×1 complex 0.9964 - 0.0254i 0.9960 - 0.0266i 0.9956 - 0.0284i 0.9961 - 0.0290i 0.9960 - 0.0301i 0.9953 - 0.0317i 0.9953 - 0.0334i 0.9952 - 0.0349i 0.9949 - 0.0367i 0.9946 - 0.0380i ⋮
hs— 2–port S-parameters
2-port S-parameters, specified as an RF Toolbox™ S-parameter object.
s_params— Scattering parameters
Scattering parameters, specified as a complex 2-by-2-by-M array where M represents the number of frequency points of the S-parameters.
z0— Reference impedance
Reference impedance of S-parameters, specified in ohms.
zs— Source impedance
Source impedance of S-parameters, specified in ohms.
zl— Load impedance
Load impedance of S-parameters, specified in ohms.
option— Transfer function type
Transfer function type, specified as an integer equal to
1 — The transfer function is the gain from the
incident voltage, Va, to the output
voltage for arbitrary source and load impedances:
The following figure shows how to compute Va from the source voltage Vs:
For the S-parameters and impedance values, the transfer function is:
The following equation shows how the preceding transfer function is related to
the transducer gain computed by the
Notice that if Zl and ZS are real, .
2 — The transfer function is the gain from the source
voltage to the output voltage for arbitrary source and load impedances:
You can use this option to compute the transfer function by setting
setting means that Γs = –1 and
Vin = Vs.
3 — The transfer function is the power-wave gain from
the incident power wave at the first port to the transmitted power wave at the
tf— Voltage transfer function
Voltage transfer function, returned as a vector of doubles.
Complex Number Support: Yes
The following figure shows the setup for computing the transfer function, along with the impedances, voltages, and the power waves used to determine the gain.
The function uses the following voltages and power waves for calculations:
Vl is the output voltage across the load impedance.
Vs is the source voltage.
Vin is the input voltage of the 2-port network.
is the incident power wave, equal to .
is the transmitted power wave, equal to .
 Gonzalez, Guillermo. Microwave Transistor Amplifiers: Analysis and Design. 2nd ed, Prentice Hall, 1997.