logic equivalence checking tutorial

489.6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 611.8 816 /FirstChar 33 The key points that the Conformal tool does not map are classified as unmapped points. 920.4 328.7 591.7] stream Sometimes this fact helps in proving a mathematical result by replacing one expression with another equivalent expression, without changing the truth value of … For the execution of LEC, the Conformal tool requires three types of files. If multibit flops are used in the design, then the issue of mapping golden netlist versus revised netlist will crop up, as flop names will be changed in revised netlist. In multibit flops, we merge two flops to form a single flop having multiple input and output pins. Do not get confused between un-mapped and non-equivalent reports. Leveraging a decade of experience in technology domain and physical design, he is now focusing on delivering complex SOC ASIC products in lower technology nodes for eInfochips’ customers. This paper gives an introduction of logical equivalence check, flow setup, steps to debug it, and solutions to fix LEC. In the un-mapped report we only see the floating nets of the undriven input pins, whereas in the non-equivalent report we see all the cells which are fanouts of this missing cell. These 152 flip-flops reported as non-equivalent are the multibit flops. << /FontDescriptor 20 0 R /Type/Font Not-mapped unmapped points are key points that are reachable but do not have a corresponding point in the logic fan-in cone of the corresponding design. No portion of this site may be copied, retransmitted, reposted, duplicated or otherwise used without the express written permission of Design And Reuse. /Widths[342.6 581 937.5 562.5 937.5 875 312.5 437.5 437.5 562.5 875 312.5 375 312.5 Let’s take a close look at the various steps of logical equivalence checks: In the setup mode, the Conformal tool reads two designs. Pratik Patel is a Senior Physical Design Engineer at eInfochips. 343.8 593.8 312.5 937.5 625 562.5 625 593.8 459.5 443.8 437.5 625 593.8 812.5 593.8 /Name/F2 This document contains a brief introduction to Synopsys Design Vision, Synopsys Formality, and Cadence Conformal tools. There are various EDA tools for performing LEC, such as Synopsys Formality and Cadence Conformal. As it can be seen in Fig-2, once we check this net (BUFT_net_362908) connection in LEC fail database, we see that it is connected only to the input pins of other cell (*_364714/A), but the other connection (driver side) of this net is missing due to unintentional cell deletion. /BaseFont/RENDNJ+CMR9 This file shows the unmapped nets where the logical connectivity is broken. The sample non-equivalent file below shows the 152 compare points that are failing in in LEC. Design passes through various steps like synthesis, place and route, sign-offs, ECOs (engineering change orders), and numerous optimizations before it reaches production. Using a real-world scenario, it also showcases the reports generated after LEC completion and suggests an easy way to find out the root cause of LEC failure. �(-��uws��U��QwD�TFQ����f4AME�+�߹��q����-���g3�[e�|w�}1? Watch-dog for poor RTL coding areas in the design. 761.6 272 489.6] We will explore a test case to see what happens if LEC fails – how to pinpoint the problem and what steps to take for resolving the same. /LastChar 196 Unmapped points are classified into three categories: After the Conformal tool maps the key points, the next step of the verification is comparison. 361.6 591.7 657.4 328.7 361.6 624.5 328.7 986.1 657.4 591.7 657.4 624.5 488.1 466.8 /BaseFont/BFYXLZ+CMR17 544 516.8 380.8 386.2 380.8 544 516.8 707.2 516.8 516.8 435.2 489.6 979.2 489.6 489.6 We are considering Conformal tool as a reference for the purpose of explaining the importance of LEC. /FontDescriptor 8 0 R 285.5 513.9 513.9 513.9 513.9 513.9 513.9 513.9 513.9 513.9 513.9 513.9 285.5 285.5 15 0 obj .scan_const file provides scan related constraints like if we want to ignore some scan connections/serdes input/output pins which are defined in this file.

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