@article{17358, abstract = {{Approximate circuits trade-off computational accuracy against improvements in hardware area, delay, or energy consumption. IP core vendors who wish to create such circuits need to convince consumers of the resulting approximation quality. As a solution we propose proof-carrying approximate circuits: The vendor creates an approximate IP core together with a certificate that proves the approximation quality. The proof certificate is bundled with the approximate IP core and sent off to the consumer. The consumer can formally verify the approximation quality of the IP core at a fraction of the typical computational cost for formal verification. In this paper, we first make the case for proof-carrying approximate circuits and then demonstrate the feasibility of the approach by a set of synthesis experiments using an exemplary approximation framework.}}, author = {{Witschen, Linus Matthias and Wiersema, Tobias and Platzner, Marco}}, issn = {{1557-9999}}, journal = {{IEEE Transactions On Very Large Scale Integration Systems}}, keywords = {{Approximate circuit synthesis, approximate computing, error metrics, formal verification, proof-carrying hardware}}, number = {{9}}, pages = {{2084 -- 2088}}, publisher = {{IEEE}}, title = {{{Proof-carrying Approximate Circuits}}}, doi = {{10.1109/TVLSI.2020.3008061}}, volume = {{28}}, year = {{2020}}, } @unpublished{16853, abstract = {{State-of-the-art frameworks for generating approximate circuits usually rely on information gained through circuit synthesis and/or verification to explore the search space and to find an optimal solution. Throughout the process, a large number of circuits may be subject to processing, leading to considerable runtimes. In this work, we propose a search which takes error bounds and pre-computed impact factors into account to reduce the number of invoked synthesis and verification processes. In our experimental results, we achieved speed-ups of up to 76x while area savings remain comparable to the reference search method, simulated annealing.}}, author = {{Witschen, Linus Matthias and Ghasemzadeh Mohammadi, Hassan and Artmann, Matthias and Platzner, Marco}}, booktitle = {{Fourth Workshop on Approximate Computing (AxC 2019)}}, keywords = {{Approximate computing, parameter selection, search space exploration, verification, circuit synthesis}}, pages = {{2}}, title = {{{Jump Search: A Fast Technique for the Synthesis of Approximate Circuits}}}, year = {{2019}}, } @inproceedings{10577, abstract = {{State-of-the-art frameworks for generating approximate circuits automatically explore the search space in an iterative process - often greedily. Synthesis and verification processes are invoked in each iteration to evaluate the found solutions and to guide the search algorithm. As a result, a large number of approximate circuits is subjected to analysis - leading to long runtimes - but only a few approximate circuits might form an acceptable solution. In this paper, we present our Jump Search (JS) method which seeks to reduce the runtime of an approximation process by reducing the number of expensive synthesis and verification steps. To reduce the runtime, JS computes impact factors for each approximation candidate in the circuit to create a selection of approximate circuits without invoking synthesis or verification processes. We denote the selection as path from which JS determines the final solution. In our experimental results, JS achieved speed-ups of up to 57x while area savings remain comparable to the reference search method, Simulated Annealing.}}, author = {{Witschen, Linus Matthias and Ghasemzadeh Mohammadi, Hassan and Artmann, Matthias and Platzner, Marco}}, booktitle = {{Proceedings of the 2019 on Great Lakes Symposium on VLSI - GLSVLSI '19}}, isbn = {{9781450362528}}, keywords = {{Approximate computing, design automation, parameter selection, circuit synthesis}}, location = {{Tysons Corner, VA, USA}}, publisher = {{ACM}}, title = {{{Jump Search: A Fast Technique for the Synthesis of Approximate Circuits}}}, doi = {{10.1145/3299874.3317998}}, year = {{2019}}, }