regarding lec and lvs

[jaya sree]

hai everyone,

It would be grateful if anyone clears my two doubts

1) during ecos , assume that i have attached buffers to wrong sinks, ( i.e if A , B are sinks to a cell , but buffer is added to A , C ), then is this LVS failure or LEC failure. Which one will detect this error

2) a) "sometimes LVS can pass , but LEC can fail "
b) " sometimes lec can pass , but LVS can fail"

which one of above is true and why

thank you
jaya sree

 

[yaoq]

LVS would not check if your functionality is correct or not, in your case, wrong buffer connection would cause failure on formal check.

 

[oratie]

if it's a simple buffer - neither LVS nor LEC failure. More probably, you will get timing violation.

LVS failure - only in case netlist and topology are different (example: you will add buffer in netlist to one net and then manually draw this buffer in topology in another net)

LEC failure - buffer function is just ouput=input, so no difference exist buffer or not.

timing failure - max transition violation (because big capacitance of net and buffer is on another net; or additional delay due to internal buffer delay)

 

[jaya sree]

so adding buffer to different sinks than previous sinks will cause LVS failure but lec pass.Did i understood correctly.Please help

 

[owen_li]

lvs compares the netlist against its corresponding layout.
It has nothing to do with lec, I think.
So a and b can both be right.
thanks

 

[oratie]

so adding buffer to different sinks than previous sinks will cause LVS failure but lec pass.Did i understood correctly.Please help

LVS failure only if you've added buffer to different sinks in netlist and layout (if you are using ECO tool capability, it is almost impossible, cause the tool is checking LVS automatically).