DC-725 GHZ SAMPLING CIRCUITS AND SUBPICOSECOND NONLINEAR TRANSMISSION-LINES USING ELEVATED COPLANAR WAVE-GUIDE

Nonlinear transmission lines (NLTL's) fabricated with Schottky diodes on GaAs were used to electrically generate 3.7-V step functions that h ad a measured 10%-90% fall time of 0.68 ps. These NLTL's were integrat ed on wafer with sampling circuits that had a measured 3-dB bandwidth of 725 GHz. Key to circuit performance are the use of low-loss, high-w ave-velocity elevated coplanar waveguide transmission lines and the el imination of active device pad parasitics by contacting devices above the plane of the wafer.