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RF and Microwave Power Amplifiers
RF Cafe Quiz #52

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All RF Cafe quizzes would make perfect 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.

Some of these books used in quizzes are available as prizes in the monthly RF Cafe Giveaway.

Note: Many answers contain passages quoted from the text.

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 the book.

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?

a)  Thermal resistance and lead inductance
b)  Thermal resistance and lead capacitance
c)  Lead frame capacitance and wire bond inductance
d)  Lead frame inductance and wire bond capacitance

2.  What change to coaxial connectors is necessary to accommodate higher frequencies?

a)  Physical size decreases
b)  Physical size increases
c)  Metallurgical compositions changes are needed
d)  No change is required

3.  What are the ramifications of the results of Question 2?

a)  Costs increase
b)  Power handling increases
c)  Power handling decreases
d)  There are none

4.  What is(are) the broad class(es) of RF power transistor(s)?

a)  Bipolar junction transistors (BJTs)
b)  Metal oxide semiconductor field effect transistors (MOSFETs)
c)  Gallium devices (GaAs and GaN)
d)  All the above

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
b)  Increases as the square root of the power back-off level
c)   Degrades linearly with the power back-off level
d)  Increases linearly with the power back-off level

6.  What breakdown condition(s) is(are) typically specified for FETs?

a)  Gate-source (BVgs)
b)  Gate-drain (BVgd)
c)  Drain-source (BVds)
d)  All the above

7.  How is the crest factor (CF) related to peak signal-power-to-average-signal-power (PAPR)?

a)  CF = √(PAPR)
b)  CF = PAPR
c)  CF = PAPR2
d)  CF is not related to PAPR

8.  What is the primary limitation of RF power transistor applications?

a)  Physical size
b)  Parasitic elements
c)  Heat dissipation
d)  Cost

9.  What is a fundamental problem with using Newton's Method in a harmonic-balance simulation?

a)  Newton's Method relies on the classical model
b)  Newton's Method is useful only in linear simulations
c)  Newton's Method is not guaranteed to converge on a solution
d)  There is no issue with using Newton's Method

10.  What is a limitation on RF power amplifier (RFPA) design margin requirements?

a)  Test equipment precision and accuracy
b)  Schedule constraints
c)  Power handling
d)  Bias voltage variation

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

Posted  August 3, 2013
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