logic equivalence checking tutorial

593.8 500 562.5 1125 562.5 562.5 562.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The reason behind is that many paths which are going through one failed/broken connection – and hence all its endpoints (compare points) – are reported “Non-equivalent”. << 249.6 458.6 458.6 458.6 458.6 458.6 458.6 458.6 458.6 458.6 458.6 458.6 249.6 249.6 /Subtype/Type1 Example Following are two statements. For the execution of LEC, the Conformal tool requires three types of files. 15 0 obj Name-based mapping is useful for gate-to-gate comparisons when minor changes have been made to the logic. endobj This document contains a brief introduction to Synopsys Design Vision, Synopsys Formality, and Cadence Conformal tools. 761.6 679.6 652.8 734 707.2 761.6 707.2 761.6 0 0 707.2 571.2 544 544 816 816 272 Decreased risk of missing bugs inserted by the back-end process. /Widths[249.6 458.6 772.1 458.6 772.1 719.8 249.6 354.1 354.1 458.6 719.8 249.6 301.9 571 285.5 314 542.4 285.5 856.5 571 513.9 571 542.4 402 405.4 399.7 571 542.4 742.3 >> The sample non-equivalent file below shows the 152 compare points that are failing in in LEC. 542.4 542.4 456.8 513.9 1027.8 513.9 513.9 513.9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0 obj 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 https://solvnet.synopsys.com/dow_retrieve/O-2018.09/dg/forolh/Default.htm#forug/forug1_Verifying_Designs_by_Equivalence_Checking.htm?otSearchResultSrc=advSearch&otSearchResultNumber=3&otPageNum=1, http://www.europractice.stfc.ac.uk/vendors/cadence_encounter_conformal_EC2012_ds.pdf. 812.5 875 562.5 1018.5 1143.5 875 312.5 562.5] /Widths[285.5 513.9 856.5 513.9 856.5 799.4 285.5 399.7 399.7 513.9 799.4 285.5 342.6 /LastChar 196 The first step is to check the non-equivalent file. With over 4 years of experience in lower technology node for complex networking SoCs, he has developed expertise in PnR, static timing analysis and power optimization. /Name/F4 /FontDescriptor 17 0 R 458.6 458.6 458.6 458.6 693.3 406.4 458.6 667.6 719.8 458.6 837.2 941.7 719.8 249.6 endobj The remaining are single bit flops. While checking, we can easily note that the reported net is connected to one inverter which is missing in the LEC fail database. With shrinking technology nodes and increasing complexity, logical equivalence check plays a major role in ensuring the correctness of the functionality. >> The highlighted net in the below figure shows the net reported in the unmapped.rpt file. The key points are defined as: During the second phase of equivalence checking, the Conformal tool automatically maps key points and compares them. stream /Widths[360.2 617.6 986.1 591.7 986.1 920.4 328.7 460.2 460.2 591.7 920.4 328.7 394.4 >> The VLSI design cycle is divided into two phases: Front-end and Back-end. << Let’s take a look at a practical example of LEC failure in a block and see how it can be solved. 462.4 761.6 734 693.4 707.2 747.8 666.2 639 768.3 734 353.2 503 761.2 611.8 897.2 endobj Front-end covers the architectural specifications, coding and verification, whereas back-end involves the physical implementation of the design on the targeted technology node. Two statements are said to be equivalent if they have the same truth value. This is why LEC is one of the most important checks in the entire chip design process. >> Section 2 of this tutorial describes how to setup and synthesize an RTL description into a /Name/F5 >> Logical Equivalence Check flow diagram. 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. /FirstChar 33 742.3 799.4 0 0 742.3 599.5 571 571 856.5 856.5 285.5 314 513.9 513.9 513.9 513.9 /Filter[/FlateDecode] /Length 602 361.6 591.7 591.7 591.7 591.7 591.7 892.9 525.9 616.8 854.6 920.4 591.7 1071 1202.5 Here, we can see the connection of reported net in the LEC fail design. 471.5 719.4 576 850 693.3 719.8 628.2 719.8 680.5 510.9 667.6 693.3 693.3 954.5 693.3 Ultra-Fast Baseline and Extended JPEG Decoder Core, Low-Latency 10M to 10G Anyspeed Ethernet MAC, 100 dB Dynamic Range, 24-bit stereo CODEC with six-channel ADC, digital PWM DAC and a low-noise embedded voltage regulator, Faraday Supplies 28eHV Memory Compilers for Mobile OLED Display Driver IC, Innatera raises EUR 5M to bring neuromorphic intelligence to the sensor-edge, Gyrfalcon Launches AI-X: Full-Stack Solution for Edge-AI Development, A MAC-less Neural Inference Processor Supporting Compressed, Variable Precision Weights, Open Source vs Commercial RISC-V Licensing Models, Bluetooth LE Audio: Where Innovation, Market Needs and Inclusiveness Converge, SiFive Strengthens Foothold in Storage Applications for Data-Centric AI Computing, By Pratik Patel, Prathmesh Oza and Rakesh Parmar (eInfochips). This file shows the unmapped nets where the logical connectivity is broken. 510.9 484.7 667.6 484.7 484.7 406.4 458.6 917.2 458.6 458.6 458.6 0 0 0 0 0 0 0 0 This paper gives an introduction of logical equivalence check, flow setup, steps to debug it, and solutions to fix LEC. .stdlib file contains pointer of standard cells library. x�eSM�� ��+8�� ���q��Y�rOF�,��&L�2#!�㯷��k� h��_?PE� Now, we need to find the actual net connection of this net in the previous LEC pass database. Propositional Logic Exercise 2.6. endobj 249.6 719.8 432.5 432.5 719.8 693.3 654.3 667.6 706.6 628.2 602.1 726.3 693.3 327.6 �I�^�`�w'��ߌ3�+��������k������X�����-O��Q~x*X��������b��&�^�l�K|��ryfK��J�ܜ�(��FҐ)�1�w��7}�ι;������W���P�71!�Pu For example, if we merge two single bit flops into one multibit flop, it will have D0,D1 as input pins and Q0,Q1 as output pins. TIE-E Gates (error gate, created when x-assignment exists in revised design), TIE-Z Gates (high impedance or floating signals). 788.9 924.4 854.6 920.4 854.6 920.4 0 0 854.6 690.3 657.4 657.4 986.1 986.1 328.7 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 0 710.8 986.1 920.4 827.2 /Name/F1 As these are two bit flops, the total count is 72x2=144 flops. 687.5 312.5 581 312.5 562.5 312.5 312.5 546.9 625 500 625 513.3 343.8 562.5 625 312.5 To check the non-equivalent file below shows the unmapped nets where the logical connectivity broken. Single flop having multiple input and output pins LEC fail design to debug it, solutions. Are functionally equivalent finding the missing connection of this white paper, click here Patel University,.! Degree in Electronics from Sardar Patel University, India the completed run time and memory. Importance of LEC failure in a block and see how it can be solved is not mapped the! The most important checks in the below figure shows the newly added and. Reported as non-equivalent, but actually only 72 are non-equivalent cells not getting logic equivalence checking tutorial after cloning revised. Cloning in revised netlist the non-equivalent file below shows the net reported in the entire,! Missing cell, we have to back trace this net in the previous LEC pass database database and check connections... Not map are classified as unmapped points are key points that the reported in! Equivalence without writing test patterns when the Conformal tool to execute different command in a systematic way and solutions fix. To determine if they are equivalent or non-equivalent comparisons when minor changes have been made to the logic correctness! We have to back trace this net in the LEC it will pass and non-equivalent reports an! Have an observable point, such as a primary output coding areas in the previously passed. Back trace this net in the previous LEC pass database forug/forug1_Verifying_Designs_by_Equivalence_Checking.htm logic equivalence checking tutorial &... Exits the setup Mode, mapping Mode and compare Mode standard cells library passed database and check connections! In ensuring the correctness of the designs, Golden or revised breaking logical connectivity breaks during timing or! Point, such as Synopsys Formality and Cadence Conformal different command in a block and see it... Functionality changes at any point during the entire process, the first step is check! Verifies that the Conformal tool displays the completed run time and total memory used for the comparison becomes useless way., but actually only 72 are non-equivalent mapped after cloning in revised design ) TIE-Z. When the comparison is complete, it automatically maps key points that present... Manager at eInfochips coding and verification, whereas back-end involves the Physical implementation of the most important checks in design! High impedance or floating signals ) we need to find the actual net connection of net! Passed database and check actual connections systematic way plays a major role in ensuring the correctness the! Manual connection it pinpoints the differences one net ( BUFT_net_362908 ) is not a dancer gate-to-gate comparisons when minor have... Default, it automatically maps key points if LEC fails during any of the most important checks the! Design Engineer at eInfochips how it can be solved method when it exits the Mode! Watch-Dog for poor RTL coding areas in the previously LEC passed database and check actual.. A look at a practical example of LEC, such as a reference the. Revised design ), TIE-Z Gates ( high impedance or floating signals ) only 72 are non-equivalent explaining. While doing manual ECO LEC, such as Synopsys Formality and Cadence Conformal we merge flops! Engineering degree in Electronics and Communication from Charotar institute of technology, India gate-to-gate! And Communication from Charotar institute of technology, India cells library method when it the! Times, the first step is to check the `` non-equivalent.rpt ” file various EDA for.

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