differentialprobe

A differential probe is a type of electronic test equipment used to measure the voltage difference between two points in a circuit. Unlike a standard oscilloscope probe, which measures the voltage of a single point relative to ground, a differential probe measures the voltage difference directly, without relying on a common ground connection. This is crucial for measuring signals in environments where ground loops or noise can corrupt measurements.

Differential probes achieve this by using two input terminals. The device internally subtracts the voltage at the negative terminal from the voltage at the positive terminal, displaying the result. This common-mode rejection is a key characteristic, meaning the probe is insensitive to voltages that are common to both input terminals. This makes them ideal for measuring floating signals, such as those found in switching power supplies, automotive circuits, and medical equipment where direct grounding might be impossible or introduce errors.

The use of a differential probe requires careful attention to probe grounding and termination to ensure accurate measurements. They are typically used with an oscilloscope or a differential measurement device. Different types of differential probes exist, including active and passive designs, each offering varying bandwidth, impedance, and common-mode rejection capabilities. Active differential probes generally offer superior performance but are more expensive and require power. Passive probes are simpler and less costly.