Reading and Writing Operation of SRAM

The diagram below is illustrate Static Random Access Memory (SRAM)Cell for the explanation.

SRAM cell is make up of 2 inverters are cross-connected to form a latch .The latch is connected to 2 bit line by transistor T1 and T2 . T1 and T2 can switch opened or closed under control of word line.When word line is ground level, the transistors are turned off and the latch retrains its state.

During the Read Operation,Word line is activated to close switches T1 and T2 .
If the cell is in state 1; the signal on b line is high and the signal on b’ line is low.The opposite is true if the cell is in state 0.Thus, b and b’ are always complements of each other’s.

The sense /write circuit at the end of the two bit line monitors their state and sets the corresponding output accordingly.

While in Write Operation ,the Sense/Write circuit drives bit lines b and b’, instead of sensing their state.It places the appropriate value on bit line b and its complement on b’ and activate the word line.This forces the cell into the corresponding state, which the cell retains when the word line is deactivated.