Electronic Circuits Book
Billy Cregin
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. It is a type of electrical circuit. For a circuit to be referred to as electronic, rather than electrical, generally at least one active component must be present. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another.[1]
Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an integrated circuit or IC, the components and interconnections are formed on the same substrate, typically a semiconductor such as doped silicon or (less commonly) gallium arsenide.[2]
The basic components of analog circuits are wires, resistors, capacitors, inductors, diodes, and transistors. Analog circuits are very commonly represented in schematic diagrams, in which wires are shown as lines, and each component has a unique symbol. Analog circuit analysis employs Kirchhoff's circuit laws: all the currents at a node (a place where wires meet), and the voltage around a closed loop of wires is 0. Wires are usually treated as ideal zero-voltage interconnections; any resistance or reactance is captured by explicitly adding a parasitic element, such as a discrete resistor or inductor. Active components such as transistors are often treated as controlled current or voltage sources: for example, a field-effect transistor can be modeled as a current source from the source to the drain, with the current controlled by the gate-source voltage.
When the circuit size is comparable to a wavelength of the relevant signal frequency, a more sophisticated approach must be used, the distributed-element model. Wires are treated as transmission lines, with nominally constant characteristic impedance, and the impedances at the start and end determine transmitted and reflected waves on the line. Circuits designed according to this approach are distributed-element circuits. Such considerations typically become important for circuit boards at frequencies above a GHz; integrated circuits are smaller and can be treated as lumped elements for frequencies less than 10GHz or so.
In digital electronic circuits, electric signals take on discrete values, to represent logical and numeric values.[4] These values represent the information that is being processed. In the vast majority of cases, binary encoding is used: one voltage (typically the more positive value) represents a binary '1' and another voltage (usually a value near the ground potential, 0 V) represents a binary '0'. Digital circuits make extensive use of transistors, interconnected to create logic gates that provide the functions of Boolean logic: AND, NAND, OR, NOR, XOR and combinations thereof. Transistors interconnected so as to provide positive feedback are used as latches and flip flops, circuits that have two or more metastable states, and remain in one of these states until changed by an external input. Digital circuits therefore can provide logic and memory, enabling them to perform arbitrary computational functions. (Memory based on flip-flops is known as static random-access memory (SRAM). Memory based on the storage of charge in a capacitor, dynamic random-access memory (DRAM), is also widely used.)
The design process for digital circuits is fundamentally different from the process for analog circuits. Each logic gate regenerates the binary signal, so the designer need not account for distortion, gain control, offset voltages, and other concerns faced in an analog design. As a consequence, extremely complex digital circuits, with billions of logic elements integrated on a single silicon chip, can be fabricated at low cost. Such digital integrated circuits are ubiquitous in modern electronic devices, such as calculators, mobile phone handsets, and computers. As digital circuits become more complex, issues of time delay, logic races, power dissipation, non-ideal switching, on-chip and inter-chip loading, and leakage currents, become limitations to circuit density, speed and performance.
Digital circuitry is used to create general purpose computing chips, such as microprocessors, and custom-designed logic circuits, known as application-specific integrated circuit (ASICs). Field-programmable gate arrays (FPGAs), chips with logic circuitry whose configuration can be modified after fabrication, are also widely used in prototyping and development.
Mixed-signal or hybrid circuits contain elements of both analog and digital circuits. Examples include comparators, timers, phase-locked loops, analog-to-digital converters, and digital-to-analog converters. Most modern radio and communications circuitry uses mixed signal circuits. For example, in a receiver, analog circuitry is used to amplify and frequency-convert signals so that they reach a suitable state to be converted into digital values, after which further signal processing can be performed in the digital domain.
In electronics, prototyping means building an actual circuit to a theoretical design to verify that it works, and to provide a physical platform for debugging it if it does not. The prototype is often constructed using techniques such as wire wrapping or using a breadboard, stripboard or perfboard, with the result being a circuit that is electrically identical to the design but not physically identical to the final product.[5]
Open-source tools like Fritzing exist to document electronic prototypes (especially the breadboard-based ones) and move toward physical production. Prototyping platforms such as Arduino also simplify the task of programming and interacting with a microcontroller.[6] The developer can choose to deploy their invention as-is using the prototyping platform, or replace it with only the microcontroller chip and the circuitry that is relevant to their product.
6.002 is designed to serve as a first course in an undergraduate electrical engineering (EE), or electrical engineering and computer science (EECS) curriculum. At MIT, 6.002 is in the core of department subjects required for all undergraduates in EECS.
The course introduces the fundamentals of the lumped circuit abstraction. Topics covered include: resistive elements and networks; independent and dependent sources; switches and MOS transistors; digital abstraction; amplifiers; energy storage elements; dynamics of first- and second-order networks; design in the time and frequency domains; and analog and digital circuits and applications. Design and lab exercises are also significant components of the course. 6.002 is worth 4 Engineering Design Points. The 6.002 content was created collaboratively by Profs. Anant Agarwal and Jeffrey H. Lang.
The Electronic Circuits and Systems (ECS) group focuses on the analysis, design, and synthesis of advanced high performance and/or low-power electronic circuits and electromagnetic structures. These range from new millimeter wave and terahertz circuits and devices to complex systems on a chip including mixed signal circuits, RF transceivers, phased arrays, power electronics, and biomedical circuits. We also develop a wide range of electromagnetic structures including micro-electromechanical systems (MEMS), integrated antennas, tunable networks, and periodic structures such as artificial impedance surfaces and metamaterials. Specific areas of current research include:
The group includes six IEEE fellows, one member of the National Academy of Engineering, and recipients of numerous other awards. We are highly involved in engineering societies, and our members typically hold positions on the administrative committees or as journal editors for the IEEE Solid-State Circuits Society, IEEE Circuits and Systems Society, IEEE Microwave Theory and Techniques society, and IEEE Antennas and Propagation Society. We are involved with multiple research centers on campus, including the Center for Wireless Communications, the Center on RF MEMS Reliability and Design Fundamentals, the California Institute for Telecommunications and Information Technology (CALIT2), and the CALIT2 Nano-3 Lab for microfabrication of solid-state, optical and RF MEMS devices. In addition, our faculty members are well connected to the local electronics, communications, aerospace, and other high-tech industries, often serving on technical advisory boards, and providing consulting for the top companies in these fields. Several semiconductor and communications companies have been started by our graduates.
Our laboratories include state of the art tools for the design, fabrication, and testing of high frequency circuits, systems, and structures. Numerical electromagnetic simulation tools include Ansoft HFSS, Sonnet EM-Suite, IE3D, CST Microwave Studio, AWR Microwave Office, and Remcom XFDTD. RF/Microwave and VLSI design tools include Agilent ADS, Cadence Design Systems software, and others. RF test equipment includes a wide range of signal generators to > 100 GHz, spectrum analyzers to > 200 GHz, bit error rate testers to > 50 Gbps, 2 port and 4 port vector network analyzers operating up to 250 GHz, phase noise measurement equipment to 100 GHz, and very fast oscilloscopes with 40 GHz bandwidth. We also have 8 probe stations capable of RF to > 300 GHz operation, facilities for circuit packaging and assembly, and access to an on-campus machine shop for fabrication of complex packages and electromagnetic structures. We have both far-field and planar near field antenna measurement systems up to 300 GHz, as well as a Faraday cage chamber for low-noise measurements. Ultra-sensitive current and source meters with < 1 fA resolution are available for ultra-low-power measurements.
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