A Mesfet Sampler with 20 Picosecond Step Response Time

A picosecond GaAs MESFET sampling gate employing a NEC710 as a resistive switch is designed and tested in hybrid technology. The 10-90% transition duration of the step response is 22ps. The dynamic operation is studied with a precise determination of transmitted and reflected picosecond waveforms at the different ports of the circuit during the capture of a single sample. Experimental results are analyzed using full time domain simulation of the circuit including propagation effects, measurement equipment responses.