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ECE 710
Microwave Circuits $
Patrick Roblin
Department of Electrical & Computer Engineering
The Ohio State University Columbus, OH 43210
Instructor: & OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 0 The Ohio State University % '
Lecture # 1 $ 1. Syllabus 2. ADS design package 3. Laboratory issues 4. Overview of course 5. Distributed circuit basics & OHIO S ATE T
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II. ADS design package $ We will use the \Advanced Design System" (ADS) CAD package developed by Agilent, Inc. extensively in this course. ADS is installed on the ER4 computers 20 student licenses so please run ADS only when needed. ADS allows schematic design, simulation, and optimization of microwave circuits. ADS can also generate circuit layouts for fabrication in lab 3. Handouts providing some information on ADS coming later this week. Best information source is the online tutorial. You will need to complete this as part of your work for HW # 1.
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III. Laboratory issues $ A microwave laboratory is a part of ECE 710 the lab is room CL 305 There are three lab assignments: (i) 1 port measurements, (ii) 24 port measurements, and (iii) design, fab, and testing of a passive device An \open lab" policy is used sign up for times (2 hours/wk) on lab door. Times not used available rst come rst serve. Obtain key from receptionist in DL 205 MF 95. Need to show ID for proof of enrollment in ECE 710. Students work together in team consisting of 34 students. One report turned in per team. Expect minimum 23 hours per week of lab work. & Lab manual will be distributed later this week describes procedures and labs in more detail. OHIO S ATE T
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IV. Overview of course $ In ECE 710 we will study basic passive devices used in microwave circuit systems. Passive devices are those which do not produce any power themselves, i.e. there is never any gain involved. These include impedance matching networks, couplers, lters, attenuators, phase shifters, etc. We will base most of our understanding on transmission line theory combined with network theory. In cases where this is not su cient, we will rely on \handbook" methods to model fringing/external eld e ects. & We will also learn many of the basic quantities involved in design of any microwave system (i.e. S parameters, impedance issues, etc.) 4 OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin The Ohio State University % ' Microwave Frequencies $ & Microwave frequencies typically range from 0.3 to 300 GHz: Frequencies f (GHz) 0.3 3 30 300 Wavelength (free space) 1 m 10 cm 1 cm 1 mm Examples of important frequency bands: Radio (AM,Shortwave,FM) 535 kHz108 MHz TV (VHFUHF) 54890 MHz GPS 1.5 GHz AMPS (cellular phone) 824894 MHz PCS (cellular phone) 1.9 GHz Microwave Oven 2.45 GHz Bluetooth (ISM band) 2.42.5 GHz Collision avoidance 7677 GHz US UWB 3.110.6 GHz 5 OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin The Ohio State University % '
Displacement Waves $ Examples of waves: sound waves and water waves, light voltage measured across a twowire line. t v(x t) = sin 2 T ; x = sin(!t ; x) with T the temporal period, the spatial period, ! = 2 f the radial frequency, and = 2 the wave vector. Here v(x t) could represent the instantaneous Wave motion λ Wavelength & Position OHIO S ATE T
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Phase Velocity $
T vp = dx = T = ! dt
(1) Consider a wave of the form: v(x t) = sin 2 t ; x Wave velocity is obtained by keeping the phase term constant: 2 t ; x = constant or d t ;x =0 T T which yields the phase velocity vp The phase velocity for an electromagnetic wave is the speed of light in the medium considered ( r ' 1) vp = c=p r r ' c=p r :
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Examples of Wave E ects 1 $
=
s skin e ect: the electromagnetic waves do no penetrate inside conductor beyond the skin depth: ! 2 where is the conductor conductivity and the conductor permeability. The conductor will therefore increase with frequency To reduce loss the conductors are plated with gold or silver & OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 8 The Ohio State University % ' Examples of Wave E ects 2 $ Resonances: a wave can cross 2 barriers (e.g., semitransparent mirrors) without being attenuated & OHIO S ATE T
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lifeguard Sand Examples of Wave E ects 2 $
The beach The propagation of waves from a point A to a point B follows the fastest path in time, not the shortest path in length Fastest path Straight path velocity v 1 Water velocity v2 & Swimmer OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 10 The Ohio State University % '
Short Examples of Wave E ects 3 $ At high frequencies the wavelength of the electrical (electromagnetic) signal is comparable to the circuits' dimension and the wave nature of the propagation of electromagnetic signal along wires needs to be accounted for.
Coaxial line An open circuit is measured λ/4 Current Voltage & 0 Position OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 11 The Ohio State University % '
V. Distributed circuit basics $ Traditional lumped element circuit theory is very useful as long as the size of the circuit remains very small compared to the wavelength of signals in the circuit. The above statement also implies that propagation time delays around the circuit are negligible. For a xed circuit size, if we keep increasing the frequency eventually we reach a point where traditional circuit theory does not apply. Since circuit theory is an approximation to Maxwell's equations, one way to solve this problem is to use Maxwell's equations to analyze a circuit. & However, a useful intermediate method is to consider circuits as \distributed circuits" which are described through transmission line theory. OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 12 The Ohio State University % ' Frequency considerations $ Since the wavelength at a speci c frequency f is = vfp , where vp is the velocity of light in the medium considered (3 108 m/s in free space) we can see that: Frequency (GHz) Free space (m) 0.3 1 3 0.1 30 0.01 300 0.001 The frequency range of approximately 0:3 to 30 GHz is considered the \microwave" band, while 30300 GHz is usually considered the \millimeterwave" band. We can see that circuits operating at microwave frequencies which have dimensions of centimeters or more will need distributed models. Current computers avoid this by shrinking the size not possible for circuits OHIO handling moderate to large powers. S ATE T
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Distributed circuit \components" $ Distributed circuit theory will allow us to replace inductors and capacitors with open or short circuit lines In many cases, we can design networks according to standard circuit theory using these \generalized" inductors and capacitors & OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 14 The Ohio State University % '
A Short History of Microwaves: $ Basic understanding of distributed electromagnetic behavior began in 1873 with Maxwell's equations. Oliver Heaviside put these equations in a more useable form and recognized that distributed circuit models could be useful in 1887. Real interest in microwave systems began during WWII when radar technology (using waveguides or coax mainly) was intensely developed. Current technologies often involve planar integrated systems (\microwave integrated circuits") and even direct fabrication of active and passive devices together (\monolithic microwave integrated circuits.") & Microwave circuits including active devices are covered in ECE 723 and ECE 832. OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 15 The Ohio State University % ' Wireless Milestone in the Development of Humanity $ 1837: Maxwell's Equations introduced by James Clerk Maxwell 1858: First o cial message by submarine cable send by Queen Victoria, in London, to President James Buchanan, in Washington, United States by submarine cables. (See: http://collections.ic.gc.ca/cable/fmessages.htm) 1885: Oliver Heaviside { A reclusive genious (did not go the university). Trained as a telegraphist. { Developed operational mathematics { Casted Maxwell equations in its modern form (4 equations instead of 20). { Established conditions for distortionless propagation in transmission lines { For further info see: http://wwwhistory.mcs.stand.ac.uk/history/Mathematicians/Heaviside.html & 18871991: Heinritz Hertz experimentally validates Maxwell's Equation 1895: Guglielmo Marconi demonstrates the rst transatlantic wireless OHIO telegraph with a test signal (1902: rst message) S ATE T
T.H.E UNIVERSITY Patrick Roblin 16 The Ohio State University % '
Wireless Milestone in the Development of Humanity II $ 1897: Lord Rayleigh develops the waveguide (hollow tube) theory 1912 The Titanic liner sinks: the importance of wireless is demonstrated when other liners informed by wireless come to her rescue. 1936: First waveguide demonstrated at AT&T by G. Southworth and MIT by W. L. Barron. 1940: Radar developed during World War II 1980: Cellular phone developed at Bell Lab. 1990present: Rapid growth of the wireless industry: pagers, cellular phones (AMPS, GSM, WCDMA), WLAN, PAN (Bluetooth, UWB), RFID.
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UNIVERSITY T.H.E & Patrick Roblin 17 The Ohio State University % ' Wireless $
Wireless & Wireless obviously refers to the propagation of electromagnetic waves without wires. In microwave engineering we focus on the propagation and processing of microwave signals guided by wires and other conductive structures. OHIO The paradox is that wireless systems do require wired microwave S ATE T systems for the generation and reception of wireless signals.
T.H.E UNIVERSITY Patrick Roblin 18 The Ohio State University % '
Microstrip Examples $ & Designs From Previous ECE 710 Courses
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UNIVERSITY T.H.E Patrick Roblin 19 The Ohio State University % '
Waveguide Examples $ & Waveguide components
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UNIVERSITY T.H.E Patrick Roblin 20 The Ohio State University % ' Microwave Integrated Circuits (MIC) Monolithic Microwave Integrated Circuits (MMIC) $ & OHIO S ATE T
UNIVERSITY T.H.E Patrick Roblin 21 The Ohio State University % '
RFIC and MMIC $ & RFIC and MMIC Ampli ers
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 Spring '11
 Roblin
 Ohio State University, microwave, Ohio State University Columbus, Patrick Roblin

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