Signal Measurement
A mathematical process used in high-frequency circuit analysis removes the parasitic effects of measurement fixtures and cables from the final test results. Through de-embedding calibration, test engineers isolate the performance of the printed circuit board under test from the coaxial adapters and launch traces used to connect it to the network analyzer. This calculation ensures that the measured scattering parameters represent only the target component or trace.
Without this correction, test fixture losses would mask the true high-speed behavior of the circuit.
Mathematical Removal
The calibration routine relies on measuring known reference standards, such as short, open, load, and thru lines fabricated on the same substrate. These measurements generate a matrix of error terms that represent the electrical behavior of the test fixture’s launch structures. The software then applies matrix inversion to subtract these error terms from the raw measurements of the active device.
This mathematical removal is performed in the frequency domain, providing a clean data set of the actual trace performance up to multi-gigahertz frequencies.
Instrument Configuration
Network analyzers require precise calibration files loaded into their memory before running automated high-frequency trace testing. If the launch geometry or substrate material changes, a new calibration must be executed to maintain measurement accuracy.
