High power nonlinear measurements: Calibration issues, real time loadpull, and other RF data

Abstract

Effective high power microwave amplifier design and system modeling require accurate nonlinear models, which, in turn, require measurement of at least 3 harmonics with NIST traceable phase reference between them. Exceeding a decade of measurement bandwidth at microwave frequencies can be problematic, and a fraction of a dB of calibration error can lead to 10's of percentage points of “disappointment” in performance for the physical prototype[1]-[2]. Issues related to calibration and accurate wideband measurements for building an S Function model are presented. Pre-measurements required for efficient model extraction can include real time loadpull and “design” of the power amplifier.