Logical Equivalence Check

Logical Equivalence Check

Please refer below my article which publish in Design and Reuse.

https://www.design-reuse.com/articles/45547/a-guide-on-logical-equivalence-checking-flow-challenges-and-benefits.html

This will give you clear understanding of what are the reason of failing LEC and ways to fix LEC with sample case study.

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Special cells and their Importance

Types of cells: Well taps (Tap Cells): This is non-logic cells. Tap cells are needed to reduce substrate and well resistance to prevent latch up. These cells generally used when the all the standard or most of the cells does not have well or substrate. - It is inserted at specific interval in the design and distance is defined as per foundry rule for specific technology. -We can insert at every row, every other row or stagger patterns also. - Most preferable way to insert the well tap is to stagger way because of reduce the total number of cells insertion in the design and reduce the total area utilization by those tap cells. End cap Cells: -This are the preplaced physical only cells. -Insert to meet certain design rules -Insert at the end of the site row, top and bottom side of the block boundary and every macro boundary. - This will also helps to reduce the drc's nearer to macros as the standard cells do not placed near to the macros...

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Different cells for multi Power domain designs

Special cells required for Multi-Voltage Design: (1) Level Shifter (2) Isolation Cell (3) Enable Level Shifter (4) Retention Flops (1) Level Shifter: Purpose of this cell is to shift the voltage from low to high as well as high to low. Generally buffer type and Latch type level shifters are available. In general H2L LS’s are very simple, L2H LS’s are little complex and are in general larger in size(double height) and have 2 power pins. There are some placement restrictions for L2H level shifter to handle noise levels in the design. Level shifters are typically used to convert signal levels and protect against sneak leakage paths. With great care, level shifters can be avoided in some cases, but this will become less practicable on a wider scale. (2) Isolation Cell: These are special cells required at the interface between blocks which are shut-down and always on. They clamp the output node to a known voltage. These cells needs to be placed in an ‘always on’ region...

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