In the real world, all electrical signals, including digital ones, are analog. An oscilloscope allows you to see analog voltages and how they change over time. Oscilloscopes are best used to evaluate signal integrity and measure analog circuit performance.
On the other hand, logic analyzers represent signals in their digital form. This is similar to a 1-bit resolution oscilloscope. But most logic analyzers have much more channels (8, 16 or even over 100 channels) than oscilloscopes. Logic analyzers are great tools for viewing digital waveforms, debugging digital communications, and characterizing digital systems with multiple lines. When debugging circuits, choosing the right tool for the job can be a crucial step. In essence, an oscilloscope is useful for measuring and visualizing 1-4-channel analog signals. The logic analyzer is best for digital systems with more than 4 channels. An oscilloscope can help you visualize analog waveforms and measure various properties such as amplitude, buzzer, transient signals, phase, and unwanted pulses. Even when debugging digital systems, you can easily measure signal integrity with an oscilloscope. However, if you need to monitor the output of a digital system and troubleshoot or capture serial and digital communication, the logic analyzer is usually the better tool. Logic analyzers usually offer more channels than an oscilloscope and can view data in state mode where one of the channels acts as a clock.
Differences Between Oscilloscope vs Logic Analyzer
The differences between oscilloscope vs logic analyzer can be summarized in the table below:
- Measures and displays analog signals in several channels,
- Stores and displays small snapshots repeatedly,
- Displays signals in real time,
- Measures the amplitude and timing of a waveform,
- Offers real-time features such as fast Fourier transform,
- It has simple threshold or pulse width triggers that are used to represent a fixed waveform.
- Measures and displays digital signals in many channels,
- Saves data before viewing,
- Allows users to navigate potentially long recordings,
- It measures the time between data capture points,
- Offers features specific to digital systems such as protocol analyzers,
- It has a complex trigger system used to capture and filter data.
Working Principle of Oscilloscope and Logic Analyzer
The working principle differences of oscilloscope vs logic analyzer are as follows.
Prob: The part that connects to your circuit. Most probes have two ends, as an oscilloscope measures the voltage between two points.
Amplifier / Attenuator: Oscilloscopes often include circuitry to amplify or attenuate electrical signals so that they can be effectively displayed to the user. This circuit can be inside the probe or inside the oscilloscope case.
Trigger Selection: Many oscilloscopes let you choose between an internal signal or an external signal to trigger the scan that displays the captured waveform.
Control Logic: Internal logic or software that allows you to configure how the signals are captured and displayed.
ADC: Analog to Digital Converter. The ADC is responsible for periodically sampling the electrical signal and converting the voltage to digital information stored in memory. ADCs for oscilloscopes usually have a resolution of 8, 12 or 16 bits.
Probes: If you are using a logic analyzer, you may need to fit many probes in a tight space. As a result, probes are generally simple: a piece of wire with a clip and little or no circuitry. Some probes may have dozens of channels packaged in a single high density connector that requires a dedicated mounting point on your test system.
Clock Selection: Some logic analyzers let you choose which clock to use to sample signals. An internal clock will sample periodically or an input channel can be used as the clock source.
Comparator: Unlike an oscilloscope, the logic analyzer compares each input signal with a user-defined voltage threshold. If the voltage is higher than the threshold, it is stored logically high. Otherwise, logic is stored low. Because logic analyzers do not require an ADC, they usually have much more channels than oscilloscopes.
Related Blog: How to use a digital oscilloscope?