A Review of Streamline Calibration Approaches for Digital Storage Oscilloscopes with Time-Interleaved Channels

The digital storage oscilloscope (DSO) has a vital role in measurement practice, since its resourcefulness fits both general purpose aims and requirements of more specific applications. A deep knowledge of DSO operation principles and available features is fundamental for technicians to best exploit the possibilities of the instrument. Operation principles regard digitization, acquisition, processing and visualization of the input waveform and concern a number of issues. For performant DSO digitizing systems, one of the most relevant issues is the calibration of the time-interleaved structure at the very heart of the instrument. Unfortunately, the calibration techniques adopted by the manufacturers are never disclosed in plain form with application notes or demos, and limited information can be read from patents, if available. In this article, the state-of-the-art of DSO technologies is reviewed; a general framework to face the calibration issue in time-interleaved systems, which is based on the generalized sampling theorem, is presented; and the case of some DSOs, which require special calibration approaches, implemented through the analysis of the input-output crosscorrelation of the individual acquisition channels, is discussed. Concluding remarks underline the value of the contribution, that provides a significant example of how more ideal acquisition channels can be realized by the combination of analog circuitry with digital processors.