CID Risk Assessment & Mitigation 2

Question 1

A CID is reviewing a high-speed design where two parallel signal traces run adjacent for 3 inches at 5 Gbps. What is the PRIMARY risk introduced by this routing?

Accepted Answer

Inductive and capacitive crosstalk causing noise on the victim trace

Answer

Long parallel high-speed traces create both inductive and capacitive coupling, injecting crosstalk noise onto the victim net.

Question 2

Which mitigation strategy most effectively reduces common-mode EMI noise generated by a high-speed differential pair on a PCB?

Accepted Answer

Maintaining tight differential pair coupling with matched lengths

Answer

Tight differential pair coupling ensures both traces carry equal and opposite currents, causing their radiated fields to cancel and suppressing common-mode EMI.

Question 3

During risk review, a designer finds that a critical clock net has no reference plane underneath it for 200 mils. What failure mode does this create?

Accepted Answer

Return current forced to take a long detour, causing ground bounce and EMI

Answer

A gap in the reference plane forces return current to detour around it, increasing loop area, ground bounce, and radiated emissions.

Question 4

A PCB design team identifies that a DDR4 bus has unequal trace lengths within a byte lane. What risk does this create and what is the standard mitigation?

Accepted Answer

Skew risk causing data setup/hold violations; mitigated by serpentine length matching

Answer

Unequal trace lengths in a DDR4 byte lane introduce timing skew that can violate setup and hold requirements, corrected by serpentine tuning to match lengths.

Question 5

What risk is associated with placing bypass capacitors far from the IC power pins on a high-frequency design?

Accepted Answer

Parasitic inductance of the long path reduces the capacitor's high-frequency effectiveness

Answer

Distance from the power pin increases the series inductance in the supply path, reducing the bypass capacitor's ability to suppress high-frequency noise.

(CID) Certified Interconnect Designer Practice Test

(CID) Certified Interconnect Designer Practice Test

CID Risk Assessment & Mitigation 2