RF and Microwave Power Amplifiers
RF Cafe Quiz #52

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.

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 (BV_gs)

b)  Gate-drain (BV_gd)

c)  Drain-source (BV_ds)

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 January 19, 2022
(updated from original post on 8/3/2013)

Quizzes from vintage electronics magazines such as Popular Electronics, Electronics-World, QST, and Radio News were published over the years - some really simple and others not so simple. Robert P. Balin created most of the quizzes for Popular Electronics. This is a listing of all I have posted thus far.