2:4 Decoder

Theory 

> A 2-to-4 decoder is a combinational circuit that converts 2 input binary signals into 4 unique output lines. Each output    represents one of the possible combinations of the 2 input bits. 

> Working:

 The decoder activates only the output line corresponding to the binary input.

  Useful in memory addressing, data multiplexing, and digital systems where a selection signal is required.

Truth Table 

Boolean expression 

d0 = a' b'

d1 = a' b

d2 = a b'

d3 = a b

Block diagram