Differences Between Digital and Analog Oscilloscopes

The oscilloscope has been a commonly used piece of testing equipment for over fifty years now and is used by TV technicians and aerospace engineers alike. Oscilloscopes are one of the most frequently used instruments in the field of electronics circuit design, testing, and troubleshooting because they have the ability to graphically depict the waveform, magnitude, and time base of electrical signals on its screen.

In addition it can be calibrated so that the magnitude and frequency can be observed with a great deal of accuracy. Most models also have more than one input, allowing for two or more signals to be observed at once. For these reasons oscilloscopes are invaluable to those seeking to observe the function and operation of electronic circuits in real time. Because electronic circuits operate in a decidedly non-visually way, an oscilloscope acts as a window into its operation.

Early oscilloscope designs were based on analog amplifier circuits which brought the signal’s amplitude to a level sufficient to drive the oscilloscope’s cathode ray tube’s deflection plates. An analog oscilloscope’s built-in sawtooth waveform moved the CRT’s beam from one side to the other and rapidly returned it for a consecutive scan, but these days it needs to be able to trigger at the exact moment of a digital event and it needs to be capable of showing what happens in other parts of the circuit when a digital event occurs (it may or may not be repetitive).

For this reason triggering systems capable of causing the oscilloscope to sweep exclusively at the instruction of the incoming pulse were developed. It was also commonly necessary to synch the horizontal sweep to the digital system’s clock frequency in order to show the digital switching events because timing was and is a high priority for those debugging a logic module.

It’s no wonder that digital oscilloscopes developed into a collection of of electronic circuits when you take into account all the functionality digital devices demanded. Digital oscilloscopes have quickly become very complex instruments that require some of the brightest minds in the digital electronics field for their design and to fine tune their performance characteristics as digital equipment — especially computers — become faster and more sophisticated.