Design of a dynamic calibrator with high accuracy and linearity

In RF/microwave power measurement using diodes, the detecting inherent characteristics lead to an open-loop measurement because there is no DC-substitution. Sensitivity and linearity differences between sensors or the drift due to aging or temperature can result in a different DC output voltage for the same RF power. So a calibrator is needed to absolute the incident power. In this paper, after the common principles of power reference source are presented, a dynamic calibrator source with high accuracy and linearity is fully discussed. The emphases are put on the methods to ensure the technical specifications associated with the accuracy, linearity, and temperature stability. The results show that the techniques of Automatic-Level-Control, the software compensation and synchronous detection compensation can dramatically improve the key performances.