use of latch for SRAM cell instead of flipflop

[rahulkumarkhokher]

Hi All,

Why does latch is used as SRAM cell instead of flipflop? As latch is used as sram cell, why sram cell does not have race around condition?


Thanks,
Rahul

 

[kemiyun]

Hey there. The thing that SRAM designers are mostly concerned with is the density of the SRAM, which requires minimum number of elements to be used. A latch can be implemented in a very small area while a true edge triggered flip flop is not as small. And they usually can get away with this because their clock timing, data, sensing cycles and everything are tightly controlled with an internal circuit. So you don't actually put the latch in a condition that it's not happy.

Actually don't take it from me, design and layout both of them and compare. It would make a difference in power too. Anyway someone with more experience might go beyond this but I believe this is the first level consideration.

 

[Anand Cool B]

Hey there. The thing that SRAM designers are mostly concerned with is the density of the SRAM, which requires minimum number of elements to be used. A latch can be implemented in a very small area while a true edge triggered flip flop is not as small. And they usually can get away with this because their clock timing, data, sensing cycles and everything are tightly controlled with an internal circuit. So you don't actually put the latch in a condition that it's not happy.

Actually don't take it from me, design and layout both of them and compare. It would make a difference in power too. Anyway someone with more experience might go beyond this but I believe this is the first level consideration.

In a simple way we can say 2 latches which make a fliflop can store 2 bit of data.So in the area where a flipflop is used we can we use 2 latches and store 2 bits of data.The race around condition comes when we use a JK flipflop so there we use master slave flipflop.But here the scenario is different the access transistors control thr read and write operation.