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A Bubble Error Correction in a Modified ROM Thermometer-to-Binary Encoder
Authors
	Bellavin M.A.
	Budanov D.O.
	Korotkov A.S.
Date of publication
	2021
DOI
	10.31114/2078-7707-2021-4-148-154
Abstract
	A flash analog-to-digital is the most commonly adopted in high-performance applications, because it is the fastest among the known ADC architectures. The most crucial characteristics of an ADC are performance, power consumption and the effective number of bits (ENOB). Typical flash ADC consists of analog and digital parts. The analog part consists of a resistor ladder and a comparator array. The digital part is a thermometer-to-binary encoder. An intermediate code between analog and digital pats is a ther-mometer code, in which the current value of input analog signal is defined by a position of the transition between logic ones and logic zeroes. Logic zeroes are placed upon this transition, logic ones are placed below it. A situation, when a monotonicity of this code is broken, results in one or several logic zeroes below the 1–0 transition. This situation is called a bubble error occurrence. The thermometer code combina-tion can be converted incorrectly, in this case the total noise of an ADC will increase. The increasing of total noise leads to the reduction of the ENOB. Thus, the bubble errors need to be corrected.. The bubble error correction circuit has been implemented and simulated in Cadence Virtuoso. The results of simulation show a total suppression of the first type bubble errors. The designed circuit acceptably reduces the encoder performance (for the worst cases the delay times are 557 ps with correction versus 225 ps without it during a schematic simulation and 616 ps with correction versus 327 ps without it during a post-layout simulation). Also un-essential increasing of power consumption (no more than 10%) should be noted.
Keywords
	encoder, thermometer code, bubble error correction, correction circuit, modified ROM architecture, flash analog-to-digital converter.
Library reference
	Bellavin M.A., Budanov D.O., Korotkov A.S. A Bubble Error Correction in a Modified ROM Thermometer-to-Binary Encoder // Problems of Perspective Micro- and Nanoelectronic Systems Development - 2021. Issue 4. P. 148-154. doi:10.31114/2078-7707-2021-4-148-154
URL of paper
	http://www.mes-conference.ru/data/year2021/pdf/D059.pdf