A High Performance Flash ADC with Programmable Word-Length.
Karunamoorthy Balasubramanian · 2006
Abstract – Owing to its high complexity the hardware development of a flash ADC of larger wordlength has always been a challenging issue. Being the fastest ADC available in practice, flash ADCs are the only solution for digitizing fast signals demanded by on-line real time digital processors. As computer designers have launched 64-bit machines into use, for real time processing applications they need wordlength compatible flash ADCs. This paper reports the development of a programmable word-length flash ADC wherein the word-length in integer multiples of 8-bits is chosen by the user by opting a combination of 3-mini switches. The architecture for the large word-length flash ADC is built on a single 8-bit flash ADC producing progressively bit slice of 8-bits with the originating analog input and its subsequent residues. The progressive accumulation of bit slices contribute to the total word-length of the ADC. The conversion process terminates with those contribution of bit slices conceding word-length which meets the programmed ones. As the complexity of the proposed large word-length ADC is only slightly greater than that of 8-bit flash ADC and adaptable to the word-length of the system, it is promising to be useful for high speed real time digital processors. Key words: flash ADC, programmable word-length, conversion time, circuit complexity, advanced architecture.