subject: Oscilloscope Probes [print this page] Oscilloscope Probes Oscilloscope Probes
It may be a challenging task to measure signals, especially high frequency ones, with oscilloscopes. Besides an oscilloscope with good functions, you should own some excellent oscilloscope probes as well. The reason is oscilloscope probes are very helpful for accurate signal measurements.
However, one thing you should remember. You should be very cautious to pick the proper scope probe, or it'll be impossible for you to get correct measurement of high speed time domain signals.
As for the classification oscilloscope probes, they can divided into six categories, namely, passive probes, active probes, current-measurement probes, optical probes, high voltage probes and differential probes.
Passive voltage probes are the most commonly used oscilloscope probes. Other specialty probes expand the range and functionality of an oscilloscope as a measurement system.
Active probes provide a wide signal acquisition bandwidth and ensure reduced device under test (DUT) loading. You are recommended to choose them when your appliance involves high-impedance, high-frequency circuit elements that demand minimal loading.
To achieve faster data rates, high speed serial data standards use differential signals. In this case, it's ideal to choose differential probes due to their broad frequency ranges, high common mode rejection ratio (CMRR), and skew matched inputs.
Current measurements are used to understand power loss, phase shift and are used as low impedance loading alternative to voltage probe measurements. Current probes measure the flux field generated by the movement of electrons through a conductor. Within the range specifications of the current probe, the flux field surrounding a conductor is converted to a linear voltage output that can be displayed and analyzed on an oscilloscope or other measurement instrument.
High voltage probes will eliminate the need to operate your ground reference oscilloscope without the proper ground connection, ensuring safe operation. Some ones may enable users' ground-reference. High voltage probes help a lot in accurate and safe measurements.
As oscilloscope probes are potential load to measured circuit, it's important to know its sensitivity to resistive, capacitive or inductive loading. Generally, the bandwidth should be three to five times wider than signals being measured. Select a probe that is at least the same frequency range as the oscilloscope being used. For example, when using a 100 MHz oscilloscope, select a minimum of 100 MHz probe. To achieve the optimum performance, choose a probe with more than twice the bandwidth of the oscilloscope.
