Question

Problem 1.

a) Carry generate and Carry propagate are defined as Gi= Ai Bi, Pi = Ai ⊕Bi, respectively (i = 0, 1). Show the algebraic expressions for SUM (S1, S0) and CARRY-OUT (C2, C1) functions of a 2-bit adder in terms of Gi, Pi, Ci. A and B are 2-bit unsigned integers. Ci are carries.  

b) Show the schematics for the RIPPLE-CARRY implementation of C2 of the carry generator with inputs

G0, G1, P0, P1 and C0 for the 2-bit adder. Complemented inputs are available. One can use only

NAND and NOR gates with any number of inputs. No additional inverters are available.  

Estimate the propagation delay of the circuit if the typical delay of logic gates is 10 ns regardless of

number of inputs.   

c) Show the schematics for the CARRY-LOOKAHEAD implementation of C2 of the carry generator with

inputs G0, G1, P0, P1, and C0 for the 2-bit adder. One can use only NAND and NOR gates with any

number of inputs. No additional inverters are available. Estimate the propagation delay of the circuit if the typical delay of logic gates is 10 ns regardless

of number of inputs.  

Answer 1