Perform High Impedance Measurements With Spectrum Analyzers

Circuit design and debugging pose challenges due to limited test points, especially in RF design where multiple signal path measurements are required. Traditionally, RF designers used connectors along the path, but shrinking components and limited board space make this difficult. An alternative is using oscilloscope probes, which can connect to surface-mounted components and tracks.

However, this requires an understanding of the circuit-probe-analyzer interface. While most RF analyzers have 50 Ω impedance, oscilloscope probes differ. Modern oscilloscope probes offer high impedance, low capacitance, and broad bandwidth, making them suitable for RF measurements with spectrum analyzers. Probe interfaces for spectrum analyzers now enable direct RF testing on circuit boards, offering a practical and precise solution to this challenge.

This application note details how to use oscilloscope probes for RF measurements with spectrum analyzers.