The debate about when to select a logic analyzer or an oscilloscope is one that goes on in labs across the country. On one hand, logic analyzers allow you to capture multiple signals from digital circuits or systems and in some cases, even convert the data into information such as timing diagrams or decodes for protocols. On the other hand, oscilloscopes are tools for observing signal voltages that vary constantly and can also measure non-electrical signals like sound and convert and display them as voltages.
If you’re using the wrong instrument to detect electrical signals, you could be missing out on important data. Below are a few helpful hints for determining which instrument works best for your needs.
The bandwidth and high sample rate offered by the oscilloscope give it the ability to capture high resolution views. This makes it a good choice for measuring and displaying analog details of electric signals. Oscilloscopes are also the best choice when you need to take a look at small voltage circuits on a given signal or when time interval accuracy is necessary. However, oscilloscopes are somewhat limited with only two or four input channels to correlate a small number of digital, analog and serial signals.
The Logic Analyzer
Logic analyzers provide an ideal tool to verify and debug complex designs for electrical engineers. Logic analyzers are useful when multiple signals must be observed simultaneously, as well as when you need to look at a system's signals in the same way its hardware does. The biggest difference from the oscilloscope is the extra input channels it offers. Logic analyzers can include anywhere from 34 channels to literally thousands.
Digital and analog sampling
Most oscilloscopes use an analog to digital converter to create a reproduction of the signal within a digital system. Logic analyzers sample signals by comparing a threshold designed by the user. Oscilloscopes are useful when looking for transients or unwanted pulses, as well as looking at the shape of a waveform. Logic analyzers are useful for identifying timing problems and compile larger numbers of digital signals.
In an oscilloscope, triggering is the process that synchronizes input waveforms to the sweep, which makes the waveforms appear as though they are stationary with each sweep. With logic analyzers, triggering sets conditions to help capture acquisition and display results. Differences in triggers come from the oscilloscope’s basic modes, which are focused on isolating analog characteristics. The logic analyzer can provide extensive logic resources including word counters, timers and comparators that can help isolate issues.
However, some electrical engineers need to see the data acquired from logic analyzers and oscilloscopes at once. Manufacturers recognized the need to correlate data through an oscilloscope with information acquired through a logic analyzer and have developed hybrid solutions combining the capabilities of both devices to give users the ability to integrate data from digital and analog signals.
If you need to compare for yourself, take a look at the options from our inventory on our website, or contact the experts here at MATsolutions for reliable guidance.
Originally published June 2014; Updated June 2015