Measurement of Oscilloscopes Bandwidth

Bandwidth measurement of a 63 GHz real-time bandwidth oscilloscope requires a new set of equipment with high frequency capability. The new measurement system setup requires thorough system validation, software development and validation, and measurement uncertainty evaluation. The substitution measurement method is applied in the bandwidth measurement by using a resistive power splitter to deliver an RF signal to two measurement arms. Both of the measurement arms are characterized by two power sensors to obtain the corrective factor for the tracking error of the splitter. The power sensor from one of the measurement arms is then replaced by the oscilloscope input to perform the bandwidth measurement. Uncertainty for mismatch and power sensor calibration factor are the major uncertainty contributors. The measurement uncertainty is evaluated and improved to an optimum value to minimize false reject risk.