Design of automatic calibration in digital oscilloscope

Abstract

The calibration of the oscilloscope can guarantee the reliability of its performance indicators and improve the credibility of the oscilloscope measurement results. However, the manual calibration method has a slow calibration speed and low production efficiency, and cannot meet the requirements of mass production. This paper improves the calibration method of the oscilloscope according to the hardware structure of the signal conditioning channel. In direct current (DC) gain calibration, the programmable attenuator and analog to digital converter (ADC) gain are combined to calibrate, improving DC gain calibration accuracy. In the calibration of the trigger level, both the positive and negative bias levels of the trigger are calibrated to improve the trigger level accuracy. During trigger level and channel offset calibration, calibration of all amplitude ranges is done by calibrating only one amplitude range. Under the preseted calibration accuracy, the time of automatic calibration is greatly decreased, and the efficiency of automatic calibration is improved.