Final answer:
The student's question involves designing two adders, a 64-bit ripple-carry and a 64-bit carry-lookahead adder. The ripple-carry adder has higher delay and uses less area and power, whereas the carry-lookahead adder operates faster but consumes more power and area.
Step-by-step explanation:
The question deals with the design of two types of adders: 64-bit ripple-carry adder and 64-bit carry-lookahead adder with 4-bit blocks. Starting at the bottom of the hierarchy, a full adder would be constructed using basic 2-input gates such as AND, OR, and XOR. While the details of how to draw the circuits are beyond the scope of this platform, we can proceed with a discussion of their characteristics.
Comparison of Adders
The ripple-carry adder consists of a series of full adders cascaded together, with the carry output of one adder becoming the carry input to the next. In contrast, the carry-lookahead adder uses additional logic to compute the carry signals in advance, thereby reducing propagation delay.
Delay: The ripple-carry adder has a higher delay because each carry output must propagate through all subsequent stages. The carry-lookahead adder, with its carry lookahead logic, operates faster at the cost of additional complexity.
Power: The carry-lookahead adder tends to consume more power due to its additional logic circuits.
Area: The ripple-carry adder occupies less area because it has a simpler design, while the carry-lookahead adder requires more area due to the additional circuitry for the carry computation logic.