1. S-parameters measurements
If you use Spectre
In the schematic view, add instance “psin” from analoglib/sources/ports
Each port of the DUT is connected to one “psin”
In the property form of “psin”, specify the resistance (like 50ohm) and port number. For each “psin”, the port number should be different (such as “1”, “2”). (As shown in Fig.2)
Open analog artist window (As shown in Fig.3)
Click “Analyses” and then click “sp” (“sp” stands for “S-parameter"), fill out the form like what is shown in Fig.4. Make sure you push the “select” button in “S-parameter analysis” session and then choose the right ports in your schematic. Make sure the port names show up in the window. Then click “ok”.
Run simulation
7. After you finish simulation, choose result/direct plot/main form, the pop-up window is shown in Fig.5
8. In the form, select “sp” in the “function" session and select the plot type and modifier that you want. Then you can plot Sij by clicking the corresponding button.
9. If you are interested in the NF, you can click “NF” in the “function” session and plot NF. However, this number is not accurate
If you want to measure the S-parameters of three-port DUT like mixer. You can ground one input and measure the S-parameters. Repeat for the other input port. You have two sets of S-parameter.
If you use Spice
11. Set up the circuit based on the definition, measure current and voltage to calculate the S-parameters.

2. DUT
PORT0
r:50
PORT1
psin
Fig.1. S-parameter measurement of DUT

3. Fig.2. The property form of instance “psin”

4. Fig.3. Analog Artist window

5. Fig.4. “sp” analysis form

6. Fig.5. Direct plot form