A sub-200 picosecond GaAs sample-and-hold circuit for a multi-gigasample/second integrated circuit

We report initial results on a digital/analog, 1-micron gate GaAs MESFET IC whose purpose is to record with bandwidths exceeding 1 GHz nonrepetitive analog transient waveforms of a few nanoseconds duration. Specialized buffered-fet logic digital circuits with T
pd
as low as 70 psec generate a pulse burst that strobe a series of 20 linear gate sample-and-hold circuits. These 3
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gate MESFET sampling circuits have demonstrated sampling apertures of less than 200 psec, without pretriggering required. Backgating effects on the circuit design and performance and high speed techniques are reviewed. Earlier work (1) on this scheme has been extended from 1nsec step inputs to 100 psec and variable biasing in the linear gate circuit has been added.