Standard Protocol for De-Embedding S-Parameter Calibration Data on Test Benches
Stripping test fixture phase delay and magnitude loss from raw vector network analyzer measurements ensures true S-parameter extraction.
ABCD Matrix
Meaning
Mathematical cascades of two-port electrical networks use matrix representations to compute transmission properties. An abcd matrix represents a chain of electronic components where the input voltage and current are defined directly as functions of the output voltage and current.
Cascade Calculation
Multiport networks are simplified by multiplying the individual matrices of each component sequentially from source to load. This chain calculation allows designers to model complex transmission lines or connector transitions as a single composite matrix without solving system-level differential equations. A series impedance has a straightforward representation that makes hand calculation practical.
Circuit simulators execute this multiplication to model trace losses in multi-layer board structures.
Network Parameter
Transmission line parameters require conversions before they can be displayed on vector network analyzers. The scattering parameters gathered during physical board tests are converted into the matrix format to simplify cascade calculations. This representation lacks the symmetry of S-parameters but handles series and shunt components much faster.
Interface Limit
High frequency active devices are difficult to characterize using this format because open and short circuit currents are unstable at microwave limits. Standard probes measure reflected waves instead of voltage or current. The calculated parameters remain valid only within linear operation boundaries.