CID Interconnect Modeling & Simulation 3

Question 1

What condition must be satisfied for a multiport S-parameter model to be considered passive?

Accepted Answer

The scattering matrix must satisfy S^H·S ≤ I (semi-definite condition)

Answer

Passivity requires that the scattering matrix S satisfies the condition I − S^H·S ≥ 0 (positive semi-definite), ensuring the network cannot generate power.

Question 2

In IBIS (Input/Output Buffer Information Specification) modeling, what does the 'Ramp' data describe?

Accepted Answer

The output rise and fall slew rate for signal edge characterization

Answer

The Ramp section in an IBIS model provides the output voltage transition rate (dV/dt) measured from 20% to 80% of the swing for both rising and falling edges.

Question 3

Which effect does the 'skin depth' directly influence in an interconnect at high frequency?

Accepted Answer

Current crowding toward the conductor surface, increasing resistance

Answer

At high frequency, skin effect confines current to a thin layer near the conductor surface, reducing the effective cross-sectional area and increasing AC resistance.

Question 4

When performing eye diagram simulation, what parameter directly quantifies the horizontal opening of the eye?

Accepted Answer

Jitter margin (eye width)

Answer

Eye width (jitter margin) measures the time interval during which the eye is open horizontally, representing the available timing margin for correct bit sampling.

Question 5

In a differential pair interconnect model, 'mode conversion' (S_SCD21) indicates:

Accepted Answer

Conversion of differential signal to common mode signal along the channel

Answer

S_SCD21 is the mixed-mode S-parameter representing common-mode output at port 2 excited by a differential-mode input at port 1, indicating undesired mode conversion.

(CID) Certified Interconnect Designer Practice Test

(CID) Certified Interconnect Designer Practice Test

CID Interconnect Modeling & Simulation 3