Mixed-Mode Performance - Agilent Technologies N4413A User Manual

Using the Multiport Test System
How to Characterize Balanced Devices

Mixed-Mode Performance

The single-ended (unbalanced) data is not representative of the balanced performance
because of the coupling between the two sides of the balanced pair. For balanced performance,
mixed-mode S-parameters are used. For a device with two balanced ports, each of the four
quadrants represents a different mode of operation. Each quadrant includes input- and
output-reflection parameters, and forward- and reverse-transmission parameters.
For example, SDD11 represents the differential mode match on balanced port 1. SDD21 is the
differential-mode forward transmission parameter from port 1 to port 2. Note the similarities
between SDD21 and S21.
62 Chapter 3