We study three-level implementations where the first two levels represent a standard PLA form with an AND-plane and an OR-plane. This implements a 2m-output SOP. The final stage consists of m two-input programmable LUTs. The PLA outputs are paired so that the LUT outputs implement a set of m given incompletely specified functions (ISFs). Three-level structures have been studied previously, e.g. resulting in ANDOR-AND or AND-OR-XOR implementations. By using the LUT effectively, the composition of the AND-plane can be controlled to implement a PLA which has the optimum phase assignment for maximum cube sharing. For each output, we characterize the problem of all legal implementations of such a model, by defining Boolean relations that capture all the flexibility induced by the final LUT logic. The extra LUT level provides a dimension beyond simple phase assignment. We performed experiments using a Boolean relation minimizer to compare such realizations vs. SOP forms and published three-level forms, comparing areas and delays. To approximate the possible sharing in the PLA, we mapped the 2m PLA logic using SIS. We focused on experiments with two-input Boolean functions not captured by AND-OR-AND or AND-OR-XOR approaches and found good gains in many cases with affordable increases in synthesis runtimes.
Bi-decomposition using boolean relations / A. Bernasconi, R.K. Brayton, V. Ciriani, G. Trucco, T. Villa - In: Digital System Design (DSD), 2015 Euromicro Conference on[s.l] : IEEE Computer Society, 2015. - ISBN 9781467380355. - pp. 72-78 (( convegno Digital System Design tenutosi a Funchal nel 2015.
Titolo: | Bi-decomposition using boolean relations | |
Autori: | TRUCCO, GABRIELLA (Penultimo) | |
Settore Scientifico Disciplinare: | Settore INF/01 - Informatica | |
Data di pubblicazione: | 2015 | |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1109/DSD.2015.48 | |
Tipologia: | Book Part (author) | |
Appare nelle tipologie: | 03 - Contributo in volume |
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