6.3.1. Design Complexity and Overhead

Try these first

1. 1.

   What does area overhead refer to in the context of scan chains?

   Hint

   Think about the extra components and their spatial requirements.

2. 2.

   How does scan chain implementation affect performance?

   Hint

   Consider the time taken to move bits through the chain.

3. 3.

   What is area overhead?

   • Cost of manufacturing
   • Extra space used on the chip
   • Test coverage ratio

   Hint

   Think about what happens physically to the chip.

4. 4.

   True or False: Longer scan chains always improve fault detection.

   • True
   • False

   Hint

   Reflect on the negative impacts of extending scan chains.

5. 5.

   You are designing a test circuit that uses a scan chain with 50 flip-flops. Calculate the expected area overhead if each flip-flop consumes 2 mm², and suggest optimization strategies to mitigate this.

   Hint

   Focus on assessing necessity versus efficiency.

6. 6.

   A scan chain design has led to a 30% decrease in performance in a circuit. Suggest and justify three modifications to improve performance while maintaining test coverage.

   Hint

   Consider approaches that can simultaneously address both issues.