430 IEEE TRANSACTIONS ON EDUCATION. VOL. 32, NO. 4, NOVEMBER 1989

RF and Microwave Design Courses at Georgia Tech DAVID R. HERTLING, SENIOR MEMBER, IEEE, A N D ROBERT K. FEENEY, MEMBER, IEEE

Abstract-A four-course upper-level undergraduate sequence in RF (radio frequency) and microwave design offered by the School of Elec- trical Engineering at the Georgia Institute of Technology is described. The goal of these courses is to provide students with a good background in basic and advanced principles and design techniques applicable to RF and microwave engineering problems.

INTRODUCTION HE demand for RF and microwave engineers has T grown significantly in recent years [ 11. Furthermore,

other electrical engineering disciplines, such as control systems, instrumentation, and computer hardware, need engineers with expertise in high frequency design. Geor- gia Tech is one of the few schools offering a significant and structured program in RF (radio frequency) and mi- crowave design, an integral part of which is a four-course sequence described in this paper. These courses, which were developed over a ten-year period, emphasize both basic concepts and design techniques and their application to real-world RF and microwave engineering problems. Course goals, course structure, and course content are presented for each course.

DESCRIPTION AND ORGANIZATION OF THE SEQUENCE The four courses in the sequence are entitled: “Intro-

duction to RF Design,” “RF Amplifier Design,” “Ad- vanced RF Amplifier and Oscillator Design,” and “Ra- dio Receiver and Transmitter Design.” As their titles indicate, these courses emphasize design principles and therefore each counts as three hours of design toward the ABET requirement of 14 elective design hours. Student interest in these courses has been high with approximate annual enrollments of 150 students for the first course of- fered three times per year, 90 for the second course of- fered twice per year, and 25 for each of the two advanced courses offered once per year. Enrollment of these classes consists of primarily of seniors; however, graduate stu- dents interested in RF and microwave engineering also take them.

The prerequisites for beginning the sequence are com- pletion of the undergraduate electromagnetics course which covers transmission lines, the undergraduate sys- tems course which covers modulation and demodulation, and the undergraduate circuits and electronics sequence.

Manuscript received April 6, 1988; revised February 25, 1989. The authors are with the School of Electrical Engineering, Georgia In-

IEEE Log Number 8930747. stitute of Technology, Atlanta, CA 30332.

The first course in the sequence, which is a prerequisite for the second course, is designed to give the necessary background material for the remaining courses. It is also, however, designed to be sufficient for students from other branches of electrical engineering who wish to take only one RF design course. The second course covers RF am- plifier design in sufficient depth to provide students with the theory and design techniques needed by RF and mi- crowave design engineers. Scattering parameters ( S pa- rameters) and microstrip networks are also introduced in the second course. After completion of the second course, either or both of the last two courses in the sequence can be taken. These courses cover advanced techniques and are intended for students who have chosen to pursue ca- reers in RF and microwave engineering.

Each course in the sequence is devoted to several as- pects of RF design and encourages the students to learn the “art” as well as the “science” of design. Practical considerations and tradeoffs such as the elimination of un- necessary components and manufacturability are always emphasized. Formal (i.e., graded) homework is not given to the students enrolled in these courses. However, the students are provided with an extensive repertory of prac- tice problems which they are encouraged to work in a timely manner. Design problems provide the major ve- hicle for students to demonstrate their competence with the course material. The problems are intended to closely resemble an industrial project and require a written report similar to those common in industry. The design prob- lems demand considerable effort on the part of the student with typically 10-20 h being needed to complete each de- sign. In spite of this large effort, most students do the problems with enthusiasm, welcoming the chance to put their academic learning to a practical use. Some students elect to actually construct their “paper design” in a later special projects course, while many others find that a completed design project impresses prospective employ- ers.

During each course, several classroom demonstrations relevant to topics covered in the lectures or in the design problems are performed. A typical classroom demonstra- tion is to show the effects of parasitic inductance and ca- pacitance on the performance of lumped element compo- nents using a vector impedance meter and a network analyzer. Swept frequency measurements on bandpass amplifiers and microstrip filters are also made with a net- work analyzer. Many examples of components unique to RF systems are also passed around the class. These in- clude PI wound inductors, chip capacitors, high-power

001 8-9359/89/1100-0430$01 .OO 0 1989 IEEE

HERTLING AND FEENEY: DESIGN COURSES AT GEORGIA TECH 43 1

vacuum tubes, hybrid microwave circuit modules, and microwave integrated circuits. Printed circuit boards which have special modifications such as extra ground planes, stripline or microstrip transmission lines, and coaxial hard line are also passed around the class. These classroom demonstrations enhance student interest and are a very effective method of reinforcing lecture material.

Several textbooks have been used for the courses over the years [2 ] - [5 ] , but since no available textbooks cover the wide breadth of topics of the first three courses, class notes are currently being used. The book used for the fourth course [2] contains a good treatment of a broad range of receiver and transmitter circuits. In each course, reference books and relevant papers are recommended as good reading for the students.

Grades in each of the courses are determined on the basis of student performance in three areas. These areas and their relative weighting percentages are: two exami- nations (45 percent), design problems (30 percent), and a final examination (25 percent).

In the following sections, course objectives, course structure, and a topical outline are presented for each course in the sequence. For each course outline, the ap- proximate number of lecture hours are given for the major topics covered. Each course has 18 lecture h per quarter.

COURSE I INTRODUCTION TO RF DESIGN Course Objectives

This course is intended to provide the student with an introduction to basic principles and RF design techniques. For many students this is the first course that covers high- frequency considerations of electronic components and circuits. This course concentrates on lumped element cir- cuits in the frequency range from 1 to 1000 MHz and cov- ers both analytical and graphical design and analysis tech- niques.

Course Structure The class lecture time is allocated approximately 20

percent to basic principles and to high frequency effects of practical components. Approximately 40 percent of the time is allocated to analytical and graphical design and analysis of immittance transformation networks. The re- maining 40 percent of the lecture time is allocated to am- plifier fundamentals and RF amplifier design. Again, both analytical and graphical design and analysis techniques are covered. Throughout the course, examples of practi- cal applications are discussed to reinforce the lecture ma- terial. The first design problem requires the design of an immittance transformation network. Examples of as- signed design problems include the design of phasing net- works for phased array antennas, immittance transfor- mation networks which provide a match at multiple frequencies, networks which provide a match at one fre- quency and a “trap” to notch out an undesired signal at another frequency, and signal splitters and combiners. The design frequency range for these problems encompasses

10-200 MHz, over which the physical realization of lumped components is relatively easy.

The second design problem requires the design of an RF amplifier and each student is assigned slightly differ- ent specifications. For many students, this is the first ex- perience at an individualized assignment which differs from their classmates. This amplifier is typically a nar- row-band VHF amplifier with a specified gain at center frequency and a specified 3 dB bandwidth. These fre- quencies are high enough that the physical realizability of components covered early in the course must be consid- ered. The active device may be either inherently stable or potentially unstable and the students are required to use a combination of analytical and graphical design and anal- ysis techniques.

TOPICAL OUTLINE The topical outline for ‘‘Introduction to RF Engineer-

Lecture Hours

ing” is as follows:

Introduction (4.0) Superheterodyne Receivers

Linear two ports Nonlinear two ports

Amplifier classes Components at high frequencies Quality factor, Q

Components Resonant circuits

Maximum power transfer

Immittance Transformation Networks The immittance transformation problem Lossless networks

T and PI networks L networks

Minimum element realization Inherent bandwidth

Graphical design Resistive attenuators

Narrow-Band Transformer-like Networks Parallel RLC circuits Parallel LC with series loss Tapped element transformer-like networks

Tapped C networks Tapped L networks

Split C networks Split L networks

Split element transformer-like networks

Hybrid transformer-like networks Balanced and unbalanced networks

Two-Port Networks Y parameters Stability considerations Tunability

(5

(4.0)

432 IEEE TRANSACTIONS ON EDUCATION, VOL. 32, NO. 4, NOVEMBER 1989

Small-signal RF amplifiers Power gains and their meanings Finding the terminations for an active device

Inherently stable devices Potentially unstable devices

COURSE 2-RF AMPLIFIER DESIGN Course Objectives

This course develops and expands the concepts intro- duced in Introduction to RF Design into systematic pro- cedures for the analysis and design of RF amplifiers. Em- phasis is placed on wide-bandwidth S-parameter based design at VHF and higher frequencies. The use of micro- strip structures in UHF and microwave circuits is also covered. As in the first course, the use of both analytical and graphical techniques is stressed.

Course Structure The class lecture time is allocated approximately 20

percent to theory and techniques of RF amplifier design using Yparameters. Approximately 50 percent of the class time is allocated to theory and application of S parameters to amplifier design. Approximately 30 percent of the course is used to cover microstrip elements and hybrid networks which use both lumped and microstrip elements. Considerable time is spent discussing various tradeoffs and other considerations commonly encountered in design en- gineering.

The students demonstrate their understanding of the topics introduced in the classroom lectures by completing two design problems. The first problem, the design of a small signal, wide-bandwidth, VHF or UHF amplifier, is usually assigned after about thirty percent of the course material has been completed. This problem utilizes y pa- rameters and the Smith chart to perform an optimization, which would be very difficult to accomplish if attempted solely by analytical methods. This amplifier is imple- mented with lumped-element networks or by a combina- tion of microstrip and lumped-element networks.

The second design problem introduces the students to S-parameter based design procedures. It requires the de- sign of a wide-bandwidth, low-noise, UHF or microwave amplifier. The topology of the amplifiers required by both design problems is fairly well constrained in order to re- duce the effort required of the inexperienced students. The amplifier is implemented using microstrip or a combina- tion of microstrip and lumped elements.

TOPICAL OUTLINE The topical outline for “RF Amplifier Design” is as

Lecture Hours

follows :

Introduction and Review (1 .O) Overview of amplifier design Review of stability and gain Review of the Smith chart

(4.0)

Graphical Techniques for Y-Parameter-Based Design (3.0)

Power gain circles on the Smith chart Input admittance grids on the Smith chart Separation of stable and unstable regions Design using inherently stable transistors Design using potentially unstable transistors Frequency dependence of transistor parameters Design methodology for wide-bandwidth amplifiers

Review of graphical and analytical design methods Microstrip and stripline

Input and Output Network Design (4.0)

Impedance and electrical length Loss Construction practices

All-microstrip network design Quarter-wave and related transformers Cascaded networks

Introduction to Scattering Parameters Transmission lines and reflections Physical meanings of S parameters Calculation of S parameters Measurement of S parameters Stability criteria for S parameters

Stability with terminations of ZO Stability with arbitrary terminations Stability circles Rollett’s stability factor

Power gains in terms of S Parameters Gains for terminations of 2, Gains with arbitrary terminations Unilateral and bilateral gain equations Unilateral figure of merit Unilateral transducer gain exact when terminated with Zo

Input gain Output gain

Operating power-gain circles Available power-gain circles

Gain circles for the unilateral case

Gain circles for the nonunilateral case

Design Using Scattering Parameters (4.0) Optimum terminations in terms of S parameters

Unilateral case Nonunilateral case Conditions for simultaneous conjugate match

Unilateral figure of merit Unilateral input and output gain circles Stability and unilateral design Simple optimization method using gain circles

Operating power gain Available power gain circles Design when inherently stable Design when potentially unstable

Unilateral design

Bilateral design

HERTLING A N D FEENEY: DESIGN COURSES AT GEORGIA TECH 433

Noise and Amplijier Design Definition and types of noise

(2.5) Use of CAD in design Review of S parameters

(4.5) ~ w o - p o r t noise theory Noise figure, noise measure, and noise temperature Noise figure of cascaded amplifiers Variation of noise figure with terminations Noise circles Design for specified noise figure

Design of Microstrip Matching Networks Properties of microstrip and stripline

Phase velocity, impedance, and attenuation Models for microstrip transitions

Review of matching network design using the Smith chart

Quarter-wave and related transformers Synchronous transformers

Available gain circles Noise circles

COURSE 3-ADVANCED RF AMPLIFIER AND

OSCILLATOR DESIGN Course Objectives

This course presents advanced techniques applicable to the design of RF amplifiers and oscillators and empha- sizes advanced theory and design techniques. Considera- ble emphasis is placed on microstrip implementation of UHF and microwave circuits. In the latter part of the course, commercially available computer-aided design and analysis software packages are introduced and used to complete the second design problem.

Course Structure Approximately 25 percent of the class time is allocated

to introducing advanced aspects of S-parameter-based de- sign techniques. The same fraction of classroom instruc- tion is devoted to introducing the more sophisticated as- pects of transformation network design such as impedance inverters and lumped-element network to microstrip net- work transformations. Noise theory, low-noise design techniques, and an introduction to large-signal amplifiers occupy a total of about 25 percent of the lecture time. The remaining 25 percent of the course is devoted to an intro- duction to oscillator analysis and design. An introduction to various aspects of circuit optimization and computer- aided design methodology is included in the above ma- terial at appropriate points.

This course requires that the students complete two de- sign problems. A typical first design problem requires the design of an amplifier having a specified frequency re- sponse. The desired frequency response is achieved by a microstrip filter realized from a lumped-element proto- type. Manual optimization assisted by some computa- tional software is usually required for this problem.

The second design problem has reasonably tight speci- fications that can be achieved only by some optimization procedure; therefore, commercially available computer- aided design software is used to complete this problem.

Asynchronous transformers Filter realization using transformers Synthesis from lumped elements Impedance inverters

High-pass filters Bandpass filters

Resonators Design for specified reactance versus frequency

Gain and Stability Circles Noise Circles VSWR and return loss Multistage amplifier design

Sma &Signal Amplijier Design (4.5)

Gain and noise figure of multistage amplifiers Stability of multistage amplifiers Design techniques for multistage amplifiers

Design for specified gain, bandwidth, and noise figure Design for specified gain, bandwidth, and VSWR.

Large-Signal Amplijiers (3.5) Amplifier classes and efficiencies Dynamic range Intermodulation distortion Third-order intercept Design of large-signal linear amplifiers Design of large-signal class C amplifiers

Oscillator Design Criteria for oscillation Buildup of oscillations Negative resistance oscillators Oscillator design

Computer-Aided Design Amplifier analysis techniques Optimization methods COMPACT

TOUCHSTONE SUPER-COMPACT

TOPICAL OUTLINE COURSE 4-RADIO RECEIVER AND TRANSMITTER DESIGN The topical outline for “Advanced RF Amplifier and

Lecture Hours (1.5)

Oscillator Design” is as follows:

Overview of Amplijier and Oscillator Design

Course Objectives This course develops advanced techniques for modem

receiver and transmitter design with an emphasis on RF communication circuitry. A very wide range of RF cir- cuits from small-signal linear to high-power nonlinear

The design process Classes of amplifiers

434 IEEE TRANSACTIONS ON EDUCATION, VOL. 3 2 , NO. 4, NOVEMBER 1989

stages are covered. This course provides students a good knowledge of what types of circuitry are used in modern communications equipment and how these circuits are de- signed and analyzed.

Course Structure

Approximately 30 percent of the class time is allocated to RF system design and circuitry. Approximately 40 per- cent of the class time is dedicated to design techniques for receiving circuitry and 30 percent of class time is allo- cated to design of large-signal circuits. In this course, many examples of existing RF transmitting and receiving systems are presented and discussed. Other topics previ- ously covered in the electrical engineering curriculum such as modulation, demodulation, network theory, and filter theory are presented and examples of their applica- tion to real systems are also discussed. This blending of topics from different courses helps to reinforce basic prin- ciples and gives the students a better perspective of the electrical engineering curriculum. Additional topics such as broad-band transformer design, large-signal parame- ters, and nonlinear analysis techniques are also presented in this course.

The first design problem requires the design of a mixer and local oscillator and the interfacing of the two cir- cuits. In addition to the design of the circuits, the students must also consider practical system design problems such as image frequencies and their rejection and reduction of local oscillator feed-through to the RF stages.

The second design problem is the design of an inter- mediate frequency (IF) amplifier using a standard com- mercial integrated circuit. This design is the easiest of the design problems, and is intended to familiarize the stu- dent with and encourage the use of suitable integrated cir- cuits.

The last design problem requires the design of a large signal RF amplifier using large-signal impedances or large-signal parameters. This power amplifier is usually specified in the VHF range and can be either class B or class C operation with an output power of tens of watts.

TOPICAL OUTLINE

The topical outline for “Radio Receiver and Transmit- ter Design” is as follows:

Lecture Hours

Introduction (2.0) Types of receivers and transmitters System design considerations

Antenna temperature Free-space loss

Modulation techniques Large signal amplifiers

Small-Signal Amplijiers RF amplifiers IF amplifiers Audio amplifiers

Mixers Definitions and terms Diode mixers Transistor mixers

Oscillators Definitions and terms Oscillator theory Linear oscillators Nonlinear techniques

Detectors AM detectors

Envelope detection Synchronous detection Diode detectors FET and bipolar detectors

FM and PM detectors Pre-emphasis and de-emphasis Slope detection Quadrature detectors PLL detectors

Overall System Design Noise considerations Dynamic range Receiver tracking Automatic gain control

Feedback control Bipolar AGC circuits Dual-gate MOSFET AGC circuits

Transmitter Circuits Power amplifiers Graphical techniques AM transmitters FM transmitters High-power vacuum tube amplifers Power combining techniques

(4.0)

(4.0)

Evaluation of The Courses Good quantitative student evaluation of courses is dif-

ficult. Furthermore, it is difficult to separate the evalua- tion of the instructor from the evaluation of the course. During the ten-year period these courses have been taught, several course evaluation forms have been used at Geor- gia Tech. The first two courses of this sequence have been taught approximately 20 times each over this period and both courses have consistently received excellent-to-out- standing evaluations by greater than 90 percent of the stu- dents. In particular, students have rated them as excellent preparation for their careers. The last two courses have been taught three times each. The evaluation data on these

HERTLING AND FEENEY: DESIGN COURSES AT GEORGIA TECH 435

courses are not as extensive; however, they have received similar ratings by the students. Additional information which suggests that the courses are meeting their objec- tives has been received from the employers of students who have taken these courses. These employers have been very impressed and pleased with the ability of these entry level engineers to quickly become productive on the job.

CONCLUSIONS RF and microwave engineering systems and design are

becoming increasingly important and the demand for stu- dents trained in these areas continues to increase. To pro- vide formal education in this area, a four-course senior- level design sequence has been developed and has been described here. The four courses have been classroom tested and very positive indications of course effective- ness have been obtained. Based on evaluations by stu- dents and comments from industry, it is concluded that the four-course sequence has been successful in satisfying the needs of students.

REFERENCES [ I ] K. Aldrich and B. Ward, “RF engineering employment expansion con-

[2] H. Krauss, C . Bostian, and F . Raab, Solid State Radio Engineering.

[3] K. Clark and D. Hess, Communication Circuirs: Analysis and Design.

141 R. Carson, High Frequency Amplifers , 2nd Edition. New York:

[ 5 ] G . Gonzalez, Microwave Amplifiers. New York: Prentice Hall, 1985.

tinues,” RFDesign, vol. 10, no. 5 , pp. 57-58, May 1987.

New York: Wiley, 1980.

Reading, MA: Addison-Wesley, 1971.

Wiley, 1982.

David R. Hertling (S’69-M’77-SM’89) was born in St. Louis, MO, on October 22. 1947. He re- ceived the B.S., M.S. , and Ph.D. degrees in elec- trical engineering from the University of Illinois, Urbana, in 1970, 1971, and 1977. respectively.

His graduate work at Illinois was concerned with RF shielding and on the detection and im- aging of infrared radiation. The latter was the sub- ject of his Ph.D. dissertation. He was employed by the Harris Corporation from 1977 to 1978 where he was engaged in the design and devel-

opment of high power commercial broadcast transmitters. Since 1978 he has been a faculty member of the School of Electrical Engineering at the Georgia Institute of Technology, Atlanta, where he is currently an Asso- ciate Professor. He has been very active in teaching both undergraduate and graduate courses in analog electronics, instrumentation, and R F elec- tronics. His research at Georgia Tech has been in the areas of physical electronics, RF devices and systems. computer-aided design and analysis of electronic circuits, and microelectronics.

Dr. Hertling is a member of Tau Beta Pi.

Robert K. Feeney (M’61-M’65) was born in Al- bany. GA, on July 6. 1938. He received the B.E.E., M.S., and Ph.D. degrees from the Geor- gia Institute of Technology, Atlanta. in 1961, 1965, and 1970, respectively.

After receiving the B.E.E. degree, he served in the U . S . Army and worked for General Dynam- ics in San Diego, CA. Since joining the faculty of Electrical Engineering in 1970, he has done ex- tensive research in electron-ion cross section mea- surements and high field electron emission. Other

continuing activities include high-frequency circuit design and circuit sim- ulation. He has recently become associated with the Georgia Tech Micro- electronics Research Center where he acts as manager for the CAD sys- tems. Current activities in the center that he is associated with include CMOS analog circuit design, GaAs microwave integrated circuit design, and the development of IC analysis and design tools.