Introduction to Oscilloscope-related Terms (Part 2)

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Terms related to oscilloscope performance: The terms that will be discussed next may come in handy when you talk with friends about the performance of oscilloscopes. Understanding these terms can help you evaluate and compare the performance of different models of oscilloscopes. Bandwidth: Bandwidth is the primary parameter of an oscilloscope; it tells us the frequency range of signals that the oscilloscope can accurately measure. When the signal frequency reaches a certain level, as it increases, the oscilloscope’s ability to accurately measure the signal diminishes. The bandwidth of an oscilloscope refers to the frequency at which, when a sine wave is applied to its input, the amplitude drops to -3dB (70.7%), and this frequency is considered the bandwidth of the oscilloscope. If we use an oscilloscope with a 100MHz bandwidth to measure a sine wave with an amplitude of 1V and a frequency of 100MHz, the actual amplitude obtained will be at least 0.707V. The higher the bandwidth of an oscilloscope, the more accurate the measurements will be; of course, the price and cost also increase. So, what bandwidth should an oscilloscope have to be suitable? Generally, 5 times the maximum frequency of the signal being measured is the most appropriate bandwidth. Rise time: Rise time is another parameter that describes the frequency range that an oscilloscope can measure. When you aim to measure pulses and timing, rise time may be a more appropriate performance parameter to consider. When the rise time of a pulse is faster than the oscilloscope’s nominal rise time, the signal cannot be measured accurately. Vertical scale: The vertical scale refers to the voltage value of each grid on the oscilloscope’s vertical axis; it also indicates the extent to which the vertical amplifier can amplify weak signals. It is usually indicated as mV/div or V/div. The minimum vertical scale on a standard oscilloscope is 1 mV per division. Time base: The time base refers to the time represented by each grid on the horizontal axis of an oscilloscope. Gain accuracy and vertical resolution: Gain accuracy refers to the precision with which a vertical system attenuates or amplifies signals; the gain accuracy of commonly used oscilloscopes is around