SBIR-STTR Award

High speed (20 to 200 MHz), high resolution (16+ bits)analog-to-digital converters (ADCS) can perform an important rolein the electronic instrumentation used in particle physics. Gallium arsenide (GaAs) would seem an optimum technology for thisapplication because of its inherent radiation tolerance. However,some of its limitations have prevented its use in ADCs thus far. Recently, some commercial silicon ADCs with resolutions of 12 to 14bits have been introduced. Many of these are based on sigma-deltaarchitectures which are capable of achieving high resolution usingonly low resolution (in some cases 1-bit) flash convertersinternally, circumventing comparator offset and hysteresis, a majorstumbling block in GaAs converters. Thus, the sigma-deltatechnique appears to be a promising approach to the realization ofhigh resolution, oversampled ADCs using GaAs. The purpose of thisresearch is to explore the feasibility of and to develop a designfor a 16-bit ADC operating at conversion rates in excess of 100MHz. Phase I includes development of a design for the converterwith careful consideration given to the advantages and anomaliesassociated with various GaAs technologies. The design consists ofan optimum combination of architecture and technology. Theresulting design will be fabricated during Phase II.Anticipated Results/Potential Commercial Applications as described by the awardee:The results of this research can be used to develophigh speed analog-to-digital converters in the 100 to 200MHz speed regime for use in commercial digital radio, highdefinition television (HDTV), high speed instrumentation, andtelecommunications.

High speed (20 - 200 MHz), high resolution (16 bits) analog todigital converters (ADCS) can perform an important role in theelectronic instrumentation used in high energy physics. Galliumarsenide (GaAs) would seem to be an optimum technology for thisapplication because of its inherent radiation tolerance. However, some of its limitations have prevented its use in ADCsthus far. During Phase 1, the feasibility of using the highspeed capabilities of GaAs to implement an oversampling converterwith a 100 MHz conversion rate was investigated. Through the useof novel design techniques, a design for such a converter whichcould operate from the single 5.2V supply was developed. InPhase II, the primary technical objective is to achieve thecapability to deliver working-prototypes of the 16bit sigma-deltaconverter integrated circuit. The activities will includefabricating test circuits for evaluating the design of key ADCbuilding blocks, fabricating and characterizing a complete firstorder sigma-delta converter, developing a viable test methodologyto verify 16-bit performance, and fabricating, characterizing,and delivering working prototypes of the 16-bit converter.Anticipated Results/Potential Commercial Applications as described by the awardee:The results of this research can beused to develop high speed analog to digital converters in the100200 MHz speed regime for use in high energy physics research,commercial digital radio, high definition television (HDTV), andhigh speed instrumentation and telecommunications. The technologydeveloped is applicable to high speed pulse code modulation (PCM)encoding as well.