Stimulus-Response Tests Using a Spectrum Analyzer

Application Notes

The tracking generator provides a cost-effective way for spectrum analyzer users to expand their testing to cover more component-level characterization.

 

Introduction to Tracking Generators

 

A tracking generator is a signal source whose RF output follows the tuning of the spectrum analyzer. The tracking generator output signal is generated by mixing the signals from two or more oscillators. A simplified block diagram is shown in Figure 1.

 

The tracking generator uses the Swept LO from the spectrum analyzer and mixes that LO signal with a stable, fixed oscillator. If we tune the oscillator in the tracking generator (F’if) to the center frequency of the IF filter in the spectrum analyzer (F if), and use the difference mixing product, then the output frequency of the tracking generator (F’s ) will equal the input frequency of the spectrum analyzer (F s ). The spans of the spectrum analyzer and tracking generator are matched and synchronous and therefore precise tracking is achieved.