TWO"S complement

[lordsathish]

Hi...
Can anyone tell me how to compute the two's complement of n bit number using minimum harware... i.e using minimum number of logic circuits...
Is it possible to do this without using a n bit adder...

 

[Circuit_seller]

Hi

The simple approach is to NOT all bits and then add 1 to them.

Regards,
CS

 

[FvM]

It always implies a carry chain through all bits, although it's somewhat less than a n-bit full adder.

 

[basha_vlsi]

For finding 2's compliment first search for '1' from LSB and put upto that position as it is and the remaining bits ( upto MSB ) compliment the bit.

for searching '1' frm LSB we can use priority Encoder by prioritizing LSB as highest priority

 

[phoenix_pavan]

Circuit seller may be right
invert the bits and add 1 to the result

 

[SWINI]

easy way is to just complement bits which gives 1's complement and then add 1 to it..
may be full adder ic 7485 is also simpler..