Computer arithmetic design: Why is a carry look-ahead adder commonly preferred for binary addition in high-speed digital systems?

Introduction / Context:
Adders are central to arithmetic logic units (ALUs). Ripple-carry adders are simple but slow because each bit's carry must wait for the previous one. Carry look-ahead adders (CLAs) improve speed by computing carries in parallel using generate/propagate logic.

Given Data / Assumptions:

• Comparing ripple-carry vs. carry look-ahead techniques.
• Metric of interest: addition speed (latency).
• Accuracy of addition is identical for correct implementations.

Concept / Approach:
CLA forms carry generate (Gi = AiBi) and carry propagate (Pi = Ai + Bi) signals to compute all carries through combinational look-ahead networks. This removes the linear dependency of carry propagation and reduces critical path delay.

Step-by-Step Solution:

Verification / Alternative check:
In timing analysis, a CLA's worst-case delay is substantially less than an n-bit ripple adder (which is O(n)). Thus, CLAs are the industry standard for high-speed addition.

Why Other Options Are Wrong:

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