GaAs Analog to Digital Converter and Memory IC's for Ultra High Speed Transient Recording

The excellent electron dynamical properties of gallium arsenide enable GaAs devices to achieve high speed performance levels many times those of corresponding silicon devices. These device performance advantages carry over into integrated circuit technologies as well, aided significantly by the fact that GaAs substrate material is available in semi-insulating (>108Ωcm) form for very low parasitics in monolithic integrated circuits. This has led to the achievement of logic delays as low as 12.8ps at 77°K or 16.8ps at 300°K in the more exotic GaAs IC approaches. In the standard 1μm gate length, planar MESFET GaAs circuits, ring oscillator delays of τd=52ps at PD=1mw/gate have been demonstrated, increasing to τd=70ps at PD=2mw/gate in MSI flip flop circuits (standard ftoggle=1/5τd type-D flip flops toggle up to nearly 3 GHz). The planar ion implanted GaAs MESFET circuits have been fabricated in circuit complexities up to 1008 logic gates, with NOR gate delays as low as 150ps obtained in these LSI chips (e.g., a 35τd multiply time of 5.25ns in 8×8 bit latched parallel multiplier circuits). These 1μm gate length MESFET circuits have been fabricated on up to 3" diameter GaAs wafers using the same type of DSW optical lithography used for silicon VLSI, which is considered ample evidence that this GaAs IC technology can be cost-effective and is ready for commercialization. This paper focuses on the application of this MESFET GaAs IC technology for the types of digital memory and analog to digital converter circuits required to implement ultra high speed transient recorders.