Improve chip performance without process advances
Company: Apple
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Technical Screen
Assume you are working on a digital chip, but the semiconductor process node and basic device technology are fixed: there is no new, faster process and no major circuit-level innovation available.
Your team still wants higher performance (higher maximum clock frequency or more operations per second).
1. What kinds of changes can you make at the architecture, micro-architecture, and logic levels to improve performance under these constraints?
2. How do these changes typically trade off performance, power, and area (PPA)?
3. Using a 32-bit adder as an example, compare a simple ripple-carry adder to a faster mux-select (e.g., carry-select) adder:
- How do their delays scale with bit-width?
- How do their areas differ?
- In what scenarios would you choose each design?
Quick Answer: This question evaluates understanding of digital architecture, microarchitecture, and logic‑level techniques for improving chip performance without process advances, along with competence in performance/power/area (PPA) trade‑off analysis and arithmetic block design.