Extending Oscilloscope Bandwidth Calibrations To 27GHz

Until recently, finding a convenient solution for oscilloscope bandwidth calibrations above 6GHz using levelled sinewaves was problematic, currently the highest frequency provided by oscilloscope calibrators. Imputing equivalent bandwidth from a fast edge rise time measurement is possible (to around 15GHz with the fastest calibrator 25ps risetime edge), but may be impractical or inappropriate. Alternatively, users often resort to the added complexity of a high frequency signal generator, power splitter and power meter. A new RF calibrator greatly speeds up and simplifies oscilloscope bandwidth testing up to 27GHz. This paper overviews oscilloscope calibration, including levelled sine and fast pulse bandwidth testing methods, and describes how such an RF calibrator may be used alongside dedicated oscilloscope calibrators or other multi-product calibrators with oscilloscope calibration options. Considerations for placing trigger signal pick-off devices inside the RF calibrator's automated digital levelling loop and also evaluating and combining mismatch errors are discussed.