Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
RF and Microwave Power Amplifiers
Answers for RF Cafe Quiz
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!
Click here for the complete list of
RF Cafe Quizzes.
Note: Some material based on books have
Return to RF Cafe Quiz #52
This quiz is based on the information presented in
Handbook of RF and Microwave Power Amplifiers, by John L. B. Walker.
Cambridge University Press graciously provided
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
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 2?
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?
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)
What breakdown condition(s) is(are) typically specified for FETs?
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 (PAPR)?
a) CF = √(PAPR)
Crest factor (CF) is the square root of the peak signal-power-to-average-signal-power (PAPR)
(see page 513)
8. What is the primary limitation of RF power transistor applications?
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)
What is a limitation on RF power amplifier (RFPA) design margin requirements?
a) Test equipment precision
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)