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# Substrate Noise Coupling in Analog/RF CircuitsRF Cafe Quiz #26

All RF Cafe Quizzes make great fodder for employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job. Bonne chance, Viel Glück, がんばろう, buena suerte, удачи, in bocca al lupo, 행운을 빕니다, ádh mór, בהצלחה, lykke til, 祝你好運. Well, you know what I mean: Good luck!

Note: Some material based on books have quoted passages.

This quiz is based on the information presented in Substrate Noise Coupling in Analog/RF Circuits, by Stephane Bronkers, Geert Van der Plas, Gerd Vandersteen, and Yves Rolain. Published by Artech House.

Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.

1.  Which is NOT a class of substrate noise analysis?

a)  Generation

b)  Propagation

c)  Impact

d)  Transverse

2.  What is the most popular and straightforward method for shielding analog integrated circuits

against substrate noise?

a)  Ground plane

b)  Guard rings

c)  Copper conductors

d)  Metal shields

3. Aggressor and victim refer to what process?

a)  The design process and engineer doing the design, respectively

b)  The source of and recipient of substrate noise, respectively

c)  Hole and electron conduction, respectively

d)  Conductor and insulator substrate noise, respectively

4.  What is the best way to separate substrate coupling noise from other regional noise coupling

sources when developing mixed (digital/analog) signal devices?

a)  Dice between the regions to physically separate the digital/analog regions, then wire bond between

b)  Process a neutral region between digital / analog regions, then wire bond between

c)  Process a solid vertical metal wall between digital/analog regions, then wire bond between

d)  There is no method for totally separating substrate noise between regions

5.  At high frequencies, which off-chip noise coupling mechanism typically dominates?

a)  Capacitive coupling between PCB traces

b)  Inductive coupling between PCB traces

c)  Resistive coupling between the PCB and the die

d)  Magnetic coupling between die bond wires

6.  What is the primary source of FM modulated noise spurs?

a)  Doping impurities

b)  Heavy p-type doping

c)  Perturbations on the ground interconnect

d)  Low resistivity passivation

7.  In a VCO circuit, what is a likely mechanism for AM spur generation and intermediate frequencies?

a)  Capacitive coupling from on-chip inductors to the substrate

b)  Inductive coupling from on-chip inductors to the substrate

c)  Magnetic coupling from on-chip inductors to the substrate

d)  Resistive coupling from on-chip inductors to the substrate

8.  How are digital and analog grounds kept separate on the die?

a)  Integrate large resistors between digital / analog regions

b)  Integrate large inductors between digital / analog regions

c)  There is no effective method for separating digital / analog grounds

d)  Separate digital / analog ground metal on the die, with separate off-chip digital / analog grounding points

9.  For what purpose is parasitic extraction used?

a)  Obtaining parasitic current / voltage values for use in production testing

b)  Obtaining parasitic RLC values for publication in user datasheets

c)  Obtaining parasitic RLC values for use in simulation

d)  Obtaining parasitic current / voltage values for use in simulation

10.  What determines to a large extent the efficiency of a P+ guard ring?

a)  Impedance of the ground interconnect

b)  P-type doping density

c)  Passivation purity

d)  Voltage filtering