Meaning
De-embedding techniques isolate the performance of a device under test by removing the effects of non-standard connectors or traces. Using a 2x thru calibration involves measuring a double-length representation of the test fixture to characterize the parasitic elements present at each port. This approach assumes the fixture halves are symmetric.
Error Correction
Mathematical models provide the basis for removing unwanted signal reflections from the final measurement data. Once the 2x thru calibration captures the insertion loss and phase of the interconnects, the software subtracts these values from the live acquisition by applying a series of complex matrix operations to the raw port data. Results reflect only the electrical behavior of the central component.
Fixture Characterization
Physical trace layout determines the accuracy of the resulting s-parameter files. Engineers design the 2x thru calibration structure to mirror the impedance and material properties of the actual test path. Differences in board thickness or copper plating between the calibration coupon and the production fixture introduce systematic errors.
Computational Logic
Algorithms determine how the scattering matrices are divided to find the individual fixture responses. The 2x thru calibration routine usually assumes a perfectly matched impedance environment. It fails when the fixture halves differ from one another.
