Frequency Synthesizers: Concept to Product
RF Cafe Quiz #35

RF Engineering Quizzes - RF CafeAll 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!

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Note: Some material based on books have quoted passages.

RF Cafe Featured Book - Frequency Synthesizers: From Concept to ProductThis quiz is based on the information presented in Frequency Synthesizers: From Concept to Product, by Alexander Chenakin (Phase Matrix). Artech House is the publisher. Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.

1.  What would the spectrum analyzer display for an ideal sinewave output look like?

a)  A comb of vertical lines at the fundamental and all harmonics.

b)  A sinewave per f(ω)=a*sin (ω).

c)  A convolution of all harmonics f(ω)=Σ [a*N*sin (ω)].

d)  A single vertical line at the center frequency that has no width.

2.  For a fundamental frequency of 100 MHz, what is the first harmonic frequency?

a)  50 MHz

b)  100 MHz

c)  200 MHz

d)  1000 MHz

3.  Increasing the oscillator signal-to-thermal noise ratio has what effect on the noise curve?

a)  The entire curve shifts up.

b)  The entire curve shifts down.

c)  Only the lower frequencies shift.

d)  Only the upper frequencies shift.

4.  When is harmonic mixing typically used?

a)  When the LO signal needs to be multiplied.

b)  When harmonics cannot be filtered out.

c)  When multiple frequencies are needed.

d)  Never.

5.  What distinguishes a lumped element from a distributed element?

a)  Lumped elements have leads whereas distributed are surface mount,

b)  The physical length of the component compared to signal wavelength.

c)  The manufacturer assigns the label.

d)  There is no difference; it is a regional preference.

6.  Which circuit is most likely to be found in a

      feed-through EMI filter?





7.  Why might resistors be added in series to control ports on a synthesizer's control port?

a)  Current limiting to protect the input circuitry.

b)  A voltage drop is required for proper operation.

c)  To cancel out the negative resistance of the input port.

d)  As a less expensive to inductors.

8.  What PCB layout strategy is required for synthesizer design?

a)  All components must be parallel to each other.

b)  All components must be perpendicular to each other.

c)  Each component must be located and oriented based on how other components are placed.

d)  A shield wall must exist between every component.

9.  What is the phase noise degradation of a 1 GHz synthesizer that uses a 10 MHz reference


a)  10 dB

b)  20 dB

c)  40 dB

d)  No degradation

10.  What advantage does a Fractional-N synthesizer have over Integer-N?

a)  Fractional-N is less expensive than Integer-N.

b)  Fractional-N consumes less real estate than Integer-N.

c)  Fractional-N is much simpler than Integer-N.

d)  Fractional-N permits output frequency steps that are small that the input reference source.


Need some help? Click here for the answers and explanations.