Whitepaper
Understanding Oscilloscope Probe Specifications
This application note focuses on understanding oscilloscope probe specifications and their impact on measurement accuracy. It addresses the problem of often-overlooked probing techniques in electronic test setups and highlights how probes – including 50-ohm cables, active/passive types, and differential probes – fundamentally affect both signal integrity and DUT operation. The paper examines three key areas: physical connection to the DUT, probe electrical characteristics (bandwidth, frequency response, rise time, loading), and the effects of probing on the DUT itself. It details how using a 5cm wire as a connector can introduce up to 25nH of inductive loading, distorting waveforms. The document stresses that selecting the appropriate probe is critical; it highlights Keysight’s InfiniiMode probes (N275xA) as an example – achieving 6GHz bandwidth with browser tips for differential measurements but only 2.5 GHz or 3 GHz using solder-in/socketed tips, respectively. The paper ultimately advocates a thorough review of probe datasheets to ensure optimal measurement accuracy and test optimization.