Why Are There So Many Probe Types?

The wide range of oscilloscope models and features available is just one of the fundamental reasons for the large number of probes on the market. Different oscilloscopes require different probes. A 400 MHz oscilloscope requires a probe that supports a 400 MHz bandwidth

However, many probes with the same functions and cost compete for 100 MHz oscilloscopes, so a different set of probes must be designed to support 100 MHz bandwidth

Generally, you should choose a probe that matches the oscilloscope's bandwidth whenever possible. If you can't do this, it's best to choose a probe that exceeds the oscilloscope's bandwidth

However, bandwidth is just the beginning. Oscilloscopes may also have different input connector types and input impedances

Therefore, the probe selection must also include an oscilloscope that enables compatible use of connectors. This can be a directly compatible connector or a connection via the corresponding adapter

Some general-purpose or commercial probes may not support reading functions for all oscilloscopes. As a result, special attention must be paid when using a general-purpose probe instead of one specially recommended by the oscilloscope manufacturer

Besides differences in bandwidth and connectors, various oscilloscopes also have different input resistance and capacitance values

When using attenuator probes, this one-to-one resistance matching may be exceptional

In addition to resistor matching, the probe capacitance should also match the oscilloscope's rated input capacitance

Just the requirement for matching probes and oscilloscopes has led to a large number of basic probes on the market. As a result, different probes must be used to meet various measurement needs, which significantly increases the number of probes. The most fundamental difference lies in the voltage range being measured. Millivolt, volt, and kilovolt measurements generally require probes with different attenuation coefficients (1X, 10X, 100X).

Additionally, in many cases, the signal voltage is differential voltage. This type of differential signal is very common in telephone voice circuits, computer disk read channels, and multiphase circuits. Measuring these signals also requires another type of probe, called a differential probe

probe to the oscilloscope interface

reprinted from Tektech