An Approach to Automated Calibration for Wideband RF Systems

The accuracy of an RF test system is limited by the quality of its calibration. Fully calibrating a system can be a time-consuming process, particularly when multiple channels and many frequency points must be considered, making an automated calibration routine necessary. This work discusses a system architecture and automated calibration approach used to correct for gain variation across a channelized wideband 5.5 GHz bandwidth test asset. The calibration program collects uncorrected gain data for an array of frequency points and designs a digital filter to make the spectrum optimally flat. Additionally, a related calibration routine is described that corrects for nonlinear attenuation response by measuring the RF system response at different attenuation levels and calculating a lookup table that produces the most linear response.