Publication detail

Formal Methods for Exact Analysis of Approximate Circuits

VAŠÍČEK, Z.

Original Title

Formal Methods for Exact Analysis of Approximate Circuits

Type

journal article in Web of Science

Language

English

Original Abstract

Approximate circuits are digital circuits that are intentionally designed in such a way that the specification is violated in terms of functionality in order to obtain some improvements in power consumption, performance or area, in comparison with fully functional circuits.  To design the approximate circuits, the synthesis tools rely on the availability of a procedure checking, whether the synthesized circuits meet a specification and/or provides information about circuit quality. Compared to the traditional circuit design flow, the nature of the approximate circuits involves replacing the strict functional equivalence checking with a more advanced approach that enables us to quantify or guarantee the degree of similarity. The most common technique is to employ a circuit simulator for analysing responses for all input vectors. This approach allows us to simultaneously perform checking and quality assessment, but the exhaustive enumeration of the input vectors is tractable only for a small number of inputs. To avoid excessive run-times, a subset of all possible input vectors is typically used for complex circuits. This causes us, however, to lose the ability to guarantee that the quality of the synthesized circuits is within an acceptable range given in the specification.  The main goal of this paper is to show how to adopt formal methods such as binary decision diagrams and satisfiability solvers for exhaustive analysis of approximate circuits without explicit enumeration of all input vectors. We survey the methods for exact computation of the most important error parameters used in the context of approximate computing, propose improved algorithms and provide a detailed analysis of their performance.  The methods are benchmarked on a large set of key approximate circuits consisting of nearly 2,000 unique arithmetic instances with 8-, 12-, 16-, and 32-bit operands which helps us to identify the best algorithm and method for computation of a desired error parameter. 

Keywords

approximate computing, approximate circuits, binary decision diagrams, error metrics, error analysis, formal methods, satisfiability solvers, quality assessment

Authors

VAŠÍČEK, Z.

Released

21. 12. 2019

ISBN

2169-3536

Periodical

IEEE Access

Year of study

7

Number

1

State

United States of America

Pages from

177309

Pages to

177331

Pages count

23

URL

https://www.fit.vut.cz/research/publication/12133/

Full text in the Digital Library

http://hdl.handle.net/11012/184169

BibTex

@article{BUT161468,
  author="Zdeněk {Vašíček}",
  title="Formal Methods for Exact Analysis of Approximate Circuits",
  journal="IEEE Access",
  year="2019",
  volume="7",
  number="1",
  pages="177309--177331",
  doi="10.1109/ACCESS.2019.2958605",
  issn="2169-3536",
  url="https://www.fit.vut.cz/research/publication/12133/"
}