Testing high-frequency electronic signals with reflection-mode electroabsorption modulators

Remote testing of microwave signals to 25 GHz and digital signals to 12.5 Gb/s is demonstrated through fiber-optic cables. Reflection-mode electroabsorption modulators are used as high-impedance transducers to measure voltage and inject current. Transducers are imbedded in wafer probes, printed circuit probes and microwave packages for various applications including sensing incident and reflected microwave signals, probing serial data streams on printed circuit boards, probing digital and microwave monolithic integrated circuits, and performing time-domain reflectometry. Principal advantages of this technology are that it allows test equipment to be located at large distances from the devices being tested and that broadband signals can be remotely observed with little distortion. Index Terms--Digital measurements, electric variables measurement, electroabsorption, integrated-circuit (IC) measurements, pulse measurements, scattering parameters measurement, time-domain reflectometry, transducer.