Keith F. Anderson

Complete Pure-Mode Balanced Measurement System

Previously, the first author has shown that the nonlinear behavior (e.g. gain compression or TOI) of some balanced amplifiers can be accurately measured using single-ended measurements: amplifiers that have a balanced stage before a non-linear stage; other amplifiers require true-mode drive to give correct differential and common-mode results. This paper describes, for the first time, a complete solution to the problem of true-mode measurements. The system and method included in this makes use of a dual-source VNA to produce either pure-differential or pure-common-mode drives in both the forward and reverse direction. A method for correcting drive signal errors due to mismatch between the VNA and the device under test is introduced, as well as a method to provide full balanced error correction to all terms. Its remarkable that small modifications to a standard single-ended 4-port calibration provides all the required error terms.

A survey of techniques for improving the calibration of high-power network analyzers

High-power RF components are typically characterized by using a linear or nonlinear vector network analyzer which has been modified to operate at high power levels. These test systems can be difficult to calibrate since they may include high-power pre-amps or large attenuators, resulting in compression and noise concerns. Before calibrating such a system it is prudent to review over-power limits and address test set stability issues. Next, three types of calibration are discussed: S-parameter, power, and relative phase. Techniques described for optimizing these calibrations include setting ideal power levels, avoiding compression, noise reduction, adapter removal, de-embedding of test set modifications and a simplified power calibration sequence.