Choosing Digital Oscilloscope & Benefits

Choosing Digital Oscilloscope & Benefits

In an electronic lab, a digital oscilloscope is an important tool that helps analyze and measure the electronic circuits. These signals or measurements could be analog or digital and can be visualized on the oscilloscope screen. These measurements may be amplitude, frequency, transient response, or bandwidth, which means a good oscilloscope needs to have specifications that can perform well and give accurate results when measuring. Selection of an oscilloscope is a daunting task and depends on use and environment, but some general features that one needs to look into are as follows:

Bandwidth is the maximum range of frequency over which an oscilloscope can measure. However a prominent issue with the higher frequency bands is the significant attenuation of the signals, so a recommendation is to use the bandwidth which is 5times higher than the rated frequency, e.g. an oscilloscope with 1GHz maximum bandwidth would be able to measure signals without any attenuation at 200MHz range as the frequency increases the signal starts to attenuate at the rate of 3dB or 30%.

Transient Time is the rate at which the oscilloscope can measure or differentiate between the rising and falling edges of the signal. Like the bandwidth, the signal's rise time needs to be at least five times the listed rating of the oscilloscope.

Sample Rate is the rate at which the digital scopes sample the signal. For an entry-level scope with 200MHz of maximum bandwidth, the sampling rate is usually 1-2 Giga samples per second (GSa/s), i.e. the rate at which the oscilloscope samples the signal should be rates at least five times the maximum expected frequency.

Resolution is the ability of scope to accurately quantify each sample for example, if we take a sinusoidal waveform and use 1-bit resolution, it would look more like a square waveform and as we increase the bits the waveform looks more and more like the sinusoidal. Commonly available oscilloscopes have a resolution of 16 bits for smooth and precise sampling quantification.

Number of Channels allows you to read multiple signals through ha probe, the entry-level scopes usually have only two channels, but there are scopes available with 4 channels as well.

Probes are used to measure the output signals however they must be chosen wisely since a probe with a lower frequency band would result in wasting the upper limit. This implies that the scope’s bandwidth and the probe's bandwidth must be matched. Probes have another feature that attenuates the signal 10 times using an internal RC circuit, and this feature comes in handy when dealing with higher or lower frequency ranges, usually, it is recommended to keep the probe at 10X setting when first reading a measurement.

There are other features such as mixed-signal analysis, waveform generator, and spectrum analysis, but these complex features should only be considered when you know your work complexity otherwise, these features could add a few hundred extra dollars to the cost.

Pros of Oscilloscope

A DMM may provide multiple functionalities like AC, DC, and resistance, capacitance measurements, but for the in-depth analysis of any circuit, an oscilloscope is used. It can better understand the rise time, fall time, peak-peak measurements, peak detect, transient analysis, and even some modern scopes and do frequency analysis and plot responses, which can be saved to a USB device. Some well-known brands are Agilent benchtop, handheld scopes, Tektronix, Keysight, and UNI-T. These brands have a number of models depending upon the usage, functionality, and budget range from a few hundred dollars to thousands of dollars.