De-Embedded Measurements Using the HP 8510 Microwave Network Analyzer

This paper describes a. technique for modifying the error coefficients used inside the HP 8510A to provide a measurement vantage point different from that which normal calibration and measurement techniques will allow. Such modification enables the HP 8510A to display data as though it had been calibrated at a measurement plane separated from the actual calibration plane by an embedding network. This technique, called de-embedding, enables direct device measurement at measurement planes for which suitable calibration standards are unavailable or inconvenient to use. While not totally general, the technique can accommodate many fixturing applications (the same ones to which conventional calibration techniques apply), particularly if certain attributes are included in the design and fabrication of the fixture. The technique may be easily extended to allow embedding the device under test in a hypothetical network to allow viewing the device as though it were actually in a circuit with such a. network. Some examples are given which demonstrate the measurement of a packaged transistor in a. fixture with various amounts of de-embedding. Finally, tile same transistor is shown de-embedded from the entire fixture and with a matching/filter network embedded allowing real time observation of the "finished amplifier" performance as a function of bias conditions. author has been with HP since 1972. The majority of that time was spent as a member of a lab team developing swept microwave sources, including the HP 8350 family of broadband plug-ins. Since 1981, he has been involved with the development of the HP 8511-8515 test sets for the HP 8510 and most recently was responsible for the development of the hardware and algorithms used as part of tile HP 85014A Active Device Measurements Pac.