Return to RF Cafe Quiz #52
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!
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Whether you are an RF transistor designer, an amplifier designer or a system
designer, this is your one-stop guide to RF and microwave transistor power amplifiers.
A team of expert authors brings you up to speed on every topic, including: devices
(Si LDMOS and VDMOS, GaAs FETs, GaN HEMTs), circuit and amplifier design (discrete,
hybrid and monolithic), CAD, thermal design, reliability, and system applications/requirements
for RF and microwave transistor amplifiers. Covering state-of-the-art developments
and emphasizing practical communications applications, this is the complete professional
reference on the subject.
1. What are the two primary parasitic components of a
ceramic package for an RF power amplifier?
c) Lead frame capacitance and wire bond inductance
As a first-order approximation the lead frame parasitic capacitance can be combined
with the wire bond inductance to realize a transmission line of characteristic impedance
of 50Ω. (see page 397)
2. What change to coaxial connectors is necessary to accommodate
a) Physical size decreases
To make connectors function at higher frequencies the size is decreased...
(see page 311)
3. What are the ramifications of the results of Question
c) Power handling decreases
...this reduces both the current handling and the voltage breakdown, thus reducing
the power handling capabilities. (see page 312)
4. What is(are) the broad class(es) of RF power transistor(s)?
d) All the above
There are three broad classes of RF power transistors: BJTs, MOSFETs (vertically
and laterally diffused, VDMOS, LDMOS), and gallium devices with arsenide and nitride
(GaAs and GaN). (see page 249)
5. How is the average efficiency of a Class B amplifier
affected by power back-off?
a) Degrades as the square root of the power back-off level
The average efficiency of a Class B amplifier degrades by the square root
of the power back-off level.
(see page 561)
6. What breakdown condition(s) is(are) typically specified
d) All the above
The three breakdown voltages generally quoted for FETs are the gate-source (BVgs),
the gate-drain (BVgd), and the drain-source (BVds).
(see page 57)
7. How is the crest factor (CF) related to peak signal-power-to-average-signal-power
a) CF = √(PAPR)
Crest factor (CF) is the square root of the peak signal-power-to-average-signal-power
(see page 513)
8. What is the primary limitation of RF power transistor
b) Parasitic elements
In RF power applications, the operational effectiveness (e.g., gain, power density,
efficiency, etc.) of a transistor is mostly limited by its parasitic elements.
(see page 12)
9. What is a fundamental problem with using Newton's Method
in a harmonic-balance simulation?
c) Newton's Method is not guaranteed to converge on a solution
If the initial value is not properly chosen, Newton's Method could fail to converge
on a solution.
(see page 194)
10. What is a limitation on RF power amplifier (RFPA)
design margin requirements?
a) Test equipment precision and accuracy
How accurately the test results are acquired will ultimately advise the RFPA
engineer of how much design margin does/doesn't exist. (see page 268)
Posted January 19, 2022
(updated from original post on 8/3/2013)