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De-embedding is a new feature in 4.2.  It essentially creates the inverse of the part, such that cascading a part and the inverse of the part cancel each other out.  It is typically used when a device under test (DUT) is embedded and measured in a known fixture.  When the inverse elements of the fixture are added to the measurement, the actual device under test S-Parameters can be extracted.

Not every configuration is planned to be supported- Circuit Mason will kick out a warning if a device cannot be inverted.  Currently the balanced two port (one port on the DUT and one port out to the world) and balanced four port (two ports on the DUT and two ports out to the world) are supported in 4.2.1.  More cases will be supported in future revisions.

In TinyCAD, add two parameters: "invert_dut" and "invert_out".  Invert_dut describes the ports which are attached to the device to be de-embed- in this case SEL1 is to be de-embedded.  SEL2's port 2 is attached to the device under test (DUT, hence invert_dut has a value of 2), and SEL2's port 1 is attached to the global port _Port1 (out to the world, hence invert_out has a value of 1).

In Mason, invert_dut and invert_out are attributes of SEL2, as in the following.

   <SEL2  ref_des='SEL2' pkg_type='package' invert_dut= '2' invert_out= '1' rotate='0' node_list='1 3'>
      <__l value='1e nH'>