Novel high-impedance photoconductive sampling probe for ultra-highspeed circuit characterization

摘要

Reports on a novel probe technology applied to the measurement ofhigh-speed guided electrical signals. The probe, based on theoptoelectronic technique of photoconductive sampling, consists of ahigh-impedance gate fabricated using an interdigitated electrodestructure on semi-insulating low-temperature-MBE (molecular beamepitaxy)-grown GaAs or on silicon-on-sapphire. Its resistance is 100MΩ and its capacitance is less than 0.1 fF, making this probe veryattractive for the noninvasive, external circuit testing ofultrahigh-speed devices and circuits with a 120-GHz measurementbandwidth. A 30-ps switching time was measured for an E/D-modeInAlAs/InGaAs HIGFET inverter using the probe