On Thu, Jun 1, 2023 at 03:02 PM, Jim Lux wrote:
Consider a minicircuits 1:4 or 1:9 or 1:1 transformer. The S-parameters are
given as 4 port measurements, referenced to the centertap on one of the
windings.
Now tell me a simple expression to extract the L and mutual L and parasitic C
and R (for use in a spice model) from their data.
There are TWO different conventions for 4x4 S parameter matrices, too, for how
common mode and differential mode should be arranged.
Jim,
If you work solely in the realm of s-parameters (e.g. characterizing your load in terms of S11, etc.), you might not need to create a SPICE model, depending upon what your goal is.
Mini-circuits 4-port data ought to let you determine both CM and DM performance, as long as you have characterized your load's CM and DM impedances.
An example of how to do determine CM and DM performance with a transformer defined as a 3-port device (i.e. defined with 3-port s-parameter data) is shown here:
An approach using 4-port data should be similar, but requires defining the "ideal" transformer and the "T-connection" in terms of 4-port s-parameters, rather than the 3-port version shown (the 3-port mathematical derivation of these two ideal devices is shown in the post),.
- Jeff, k6jca
