Real-time oscilloscopes are usually called DSO (digital storage oscilloscope) or MSO (mixed signal oscilloscope). Most oscilloscopes currently on sale are real-time oscilloscopes. The bandwidth of real-time oscilloscopes ranges from a few MHz to tens of GHz, and the price ranges from several hundred dollars to several hundred thousand dollars. Sampling oscilloscopes are usually called DCA (Digital Communication Analyzer), with bandwidth ranging from tens of GHz, mainly used to analyze high-speed serial buses, optical devices, and clock signals. As the bandwidth increases, sampling oscilloscopes and real-time oscilloscopes begin to overlap in multiple application areas.

The digitalization path of real-time oscilloscope and sampling oscilloscope is basically the same. The input signal passes through the front-end signal conditioning circuit of the oscilloscope, is digitized and saved to the memory, and finally displayed on the screen. However, the basic technologies of the two oscilloscopes are quite different.

Real-time oscilloscope

Real-time oscilloscopes include trigger ASIC technology, allowing users to specify events of interest, such as rising voltage thresholds, setup and hold violations, or pattern triggers. In the normal acquisition mode, when the oscilloscope's trigger circuit observes this event, the oscilloscope will capture and save the continuous sampling points near the trigger point, and update the display with the captured data. The real-time oscilloscope can work in single capture mode or continuous capture mode. In single mode, the oscilloscope is set according to the memory depth and sampling rate to perform a single acquisition and display a set of continuous samples. After the oscilloscope captures a single trace, the user can pan and zoom to any event of interest. In the continuous operation mode, the oscilloscope continuously collects and displays every condition that matches the trigger specifications. Variable persistence or infinite persistence allows multiple captured signals to be overlaid on the original signal. The continuous mode allows the user to view the device under test in real time. Rise time or pulse width measurement, math function or FFT analysis can be performed in single acquisition or continuous repeat acquisition mode. Most real-time oscilloscopes with bandwidths below 6GHz include lMΩ and 50MΩ inputs, which can be used with a variety of probes and cables.