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Comparative analysis of methods of construction of a scanning analog-digital converter of the «time-impulse» type with a coarsely-accurate system of a counting

Keywords:

A.V. Nazarov – Dr. Sc. (Eng.), Professor, Moscow Aviation Institute (National Research University)
E-mail: rat-rut@yandex.ru
A.Z. Khodorovsky – Ph. D. (Eng.), Associate Professor, Moscow Aviation Institute (National Research University)
E-mail: ahazz@mail.ru


However they do not provide high performance. One of the ways to accelerate pro-cesses in such structures is the transition to coarse-accurate converting methods. In this converters the transformation begins with the highest discharge, which ensures the quantization of the signal with the maximum pitch and ends with the lowest step, the digitization in which occurs with the smallest step. Unfortunately, these method have significant hardware costs as well as problems related to the alignment of scales between adjacent stages of the converting. The purpose of this paper is to search for algorithms and ADC structures that do not have these drawbacks. To achieve this goal, it took: to systematize methods for constructing coarsely-accurate ADCs; to make the descriptions of algorithms and structures of perspective ver-sions of converters; conduct a comparative analysis of this group of converters; choose the option of ADC, the most preferable from the point of view of practical applica-tion and to consider the possibilities of its further improvement and application. The main distinguishing feature of coarse-accurate algorithms of converting is the use on each stage of the method of balancing discharges and alignment of quantization scales between adjacent stages of the converter. Different combinations of these methods form the entire set of possible variants construction of coarsely-accurate ADCs. For analysis these variants, a group of seven algo-rithms was chosen, for each of which different implementation options were obzerved
The algorithms and structures of the converters were described using graph theory and network algorithms, which alow to describe parallel and inde-pendent processes. Additional costs for implementation of coarse-precision methods were estimated based on the number of newly introduced algorithm operators, as well as on the costs of modifying already exist-ing ones. Along with this, when analyzing algo-rithms, much attention was paid to the problem of «zero steps», which occurs when the sequence of steps is broken. This is the case, for example, when the group of bits of any of the stages has zero values. Of the algorithms presented in the paper, the most interesting from the point of view of practi-cal application is an algorithm based on a combination of forward and backward balancing. The out-put code is formed in this case from a combination both of forward and backward codes of adjacent stages of convertering. The cost of implementation of this option is several times superior to competi-tors. In addition, in this converter, the problem of «zero steps» is practically eliminated. The simplicity of the reorganization of the algorithm of operation and the structure of this con-verter led to the idea of programmatically controlling conversion parameters. This property can be used in flexible systems of information collection and processing that require changing the parame-ters of the conversion during the operation of the system. Varying by the number of bit and the number of converting steps, it is possible to vary the ac-curacy and dynamic parameters of the ADC within a wide range. Moreover, since the basis of the deploying transducers is, as a rule, an integrator, this makes it easy to go over to noise-immune inte-grating methods of converting.

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