How do I choose an oscilloscope?

Before buying an oscilloscope

If this sounds familiar, we recommend you keep reading this article to find out what specifications you need in your oscilloscope. 

Bandwidth

You need to make sure that the oscilloscope you get has enough bandwidth to capture the highest-frequency signal you might get. Before choosing the bandwidth you need to consider if you are looking for a purely analogue or digital oscilloscope, as the bandwidth recommendations barry between them. In case you are looking for an analogue oscilloscope you need an oscilloscope with at least three times higher bandwidth than the maximum you might measure. Digital oscilloscopes will need more, at least five times higher. With the Keysight Technologies InfiniiVision and Infiniium series, you can upgrade the oscilloscope bandwidth after purchase. 

Sample Rate

The sample rate is a spec for digital scopes and it tells you how fast (how many points per second) your oscilloscope is acquiring data. Bandwidth and sample rate describe two key fundamental portions of an oscilloscope. Bandwidth describes the analogue portion and how fast the signal is able to physically acquire and the sample rate describes the digital side of the system - how fast is the digital portion able to sample the analogue input from the front end. We recommend using four to five more of your circuit's highest frequency components. 

Keysight invests heavily in ADC technology and has the highest sample rate and highest-fidelity monolithic ADCs in the oscilloscope industry. 

Number of channels

In general, the more channels your oscilloscope has, the better, although this will increase the final price. Whether to select a 2, 4, 8 or 16 channel oscilloscope, depends on your application. Most of the oscilloscopes have 2 or 4 channels, which would allow you to view and compare signal timings of your waveform while debugging a digital system with parallel data needs and additional 8 or 16 channels or more. 

More channels of acquisition and display may be required as mixed-signal designs become more complicated. A Mixed Signal Oscilloscope (MSO) combines oscilloscope features with a logic analyzer and serial bus protocol analyzer capabilities. You can collect several oscilloscopes and logic signals with a time-correlated waveform display using a Keysight MSO.

Display Quality

To view delicate waveform features and signal anomalies, choose an oscilloscope with various levels of trace intensity gradation.

The brightness (intensity) of a waveform on a display indicates how frequently a signal appears at that particular location on the display. That is, the intensity of the waveform on the display can provide information.

Memory Depth

Make sure the oscilloscope has enough memory depth to capture with a high resolution the most complex signals. The oscilloscope memory depth is related to the sample rate. A scope automatically reduces the sample rate based on how much acquisition memory it has to work with. 

To begin with, oscilloscopes with a large memory cost more. Second, deep memory acquisition of extended waveforms necessitates additional waveform processing time.

Segmented Memory

Some scopes have a special operation mode called “segmented memory acquisition.” The segmented memory can essentially extend the scope’s total acquisition time. The scope does this by dividing its available acquisition memory into smaller memory segments. The oscilloscope then selectively digitizes just the important portions of the waveform under test at a high sample rate and time-tags each segment so you know the precise time between each occurrence of trigger events. This process enables your oscilloscope to capture many successive single-shot waveforms with a very fast rearm time. Keysight scopes can be upgraded in acquisition memory and more, even years after the initial purchase

 

Are you interested in buying an oscilloscope but not sure which one you need? Speak to our technical sales engineers

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