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Clock Domain Crossing
In digital electronic design a clock domain crossing (CDC), or simply clock crossing, is the traversal of a signal in a synchronous digital circuit from one clock domain into another. If a signal does not assert long enough and is not registered, it may appear asynchronous on the incoming clock boundary. A synchronous system is composed of a single electronic oscillator that generates a clock signal, and its clock domain—the memory elements directly clocked by that signal from that oscillator, and the combinational logic attached to the outputs of those memory elements. Because of speed-of-light delays, timing skew, etc., the size of a clock domain in such a synchronous system is inversely proportional to the frequency of the clock. In early computers, typically all the digital logic ran in a single clock domain. Because of transmission line loss and distortion it is difficult to carry digital signals above 66 MHz on standard PCB traces (the clock signal is the highest fre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Signal
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits. A clock signal is produced by a clock generator. Although more complex arrangements are used, the most common clock signal is in the form of a square wave with a 50% duty cycle, usually with a fixed, constant frequency. Circuits using the clock signal for synchronization may become active at either the rising edge, falling edge, or, in the case of double data rate, both in the rising and in the falling edges of the clock cycle. Digital circuits Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action. As ICs become mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase (waves)
In physics and mathematics, the phase of a periodic function F of some real variable t (such as time) is an angle-like quantity representing the fraction of the cycle covered up to t. It is denoted \phi(t) and expressed in such a scale that it varies by one full turn as the variable t goes through each period (and F(t) goes through each complete cycle). It may be measured in any angular unit such as degrees or radians, thus increasing by 360° or 2\pi as the variable t completes a full period. This convention is especially appropriate for a sinusoidal function, since its value at any argument t then can be expressed as \phi(t), the sine of the phase, multiplied by some factor (the amplitude of the sinusoid). (The cosine may be used instead of sine, depending on where one considers each period to start.) Usually, whole turns are ignored when expressing the phase; so that \phi(t) is also a periodic function, with the same period as F, that repeatedly scans the same range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mentor Graphics
Siemens EDA is a US-based electronic design automation (EDA) multinational corporation for electrical engineering and electronics, headquartered in Wilsonville, Oregon. Founded in 1981 as Mentor Graphics, the company was acquired by Siemens in 2017. The company distributes products that assist in electronic design automation, simulation tools for analog mixed-signal design, VPN solutions, and fluid dynamics and heat transfer tools. The company leveraged Apollo Computer workstations to differentiate itself within the computer-aided engineering (CAE) market with its software and hardware. History Siemens EDA was founded as Mentor Graphics in 1981 by Tom Bruggere, Gerry Langeler, and Dave Moffenbeier, all formerly of Tektronix. The company raised $55 million in funding through an initial public offering in 1984. Mentor initially wrote software that ran only in Apollo workstations. When Mentor entered the CAE market the company had two technical differentiators: the first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cadence Design Systems
Cadence Design Systems, Inc. (stylized as cādence), headquartered in San Jose, California, is an American multinational corporation, multinational computational software company, founded in 1988 by the merger of SDA Systems and ECAD, Inc. The company produces software, Electronic hardware, hardware and silicon structures for designing integrated circuits, System on chip, systems on chips (SoCs) and printed circuit boards. History Origins Cadence Design Systems began as an Electronic design automation, electronic design automation (EDA) company, formed by the 1988 merger of Solomon Design Automation (SDA), co-founded in 1983 by A. Richard Newton, Richard Newton, Alberto Sangiovanni-Vincentelli and James Solomon, and ECAD, Inc., ECAD, a public company co-founded by Ping Chao, Glen Antle and Paul Huang in 1982. SDA's CEO Joseph Costello (software executive), Joseph Costello was appointed as CEO of the newly combined company. Executive leadership Following the resignation of Cadenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EDN (magazine)
''EDN'' is an electronics industry website and formerly a magazine owned by AspenCore Media, an Arrow Electronics company. The editor-in-chief is Majeed Ahmad. ''EDN'' was published monthly until, in April 2013, EDN announced that the print edition would cease publication after the June 2013 issue. History The first issue of ''Electrical Design News'', the original name, was published in May 1956 by Rogers Corporation of Englewood, Colorado. In January 1961, Cahners Publishing Company, Inc., of Boston, acquired Rogers Publishing Company. In February 1966, Cahners sold 40% of its company to International Publishing Company in London In 1970, the Reed Group merged with International Publishing Corporation and changed its name to Reed International Limited. Acquisition of ''EEE'' magazine Cahners Publishing Company acquired ''Electronic Equipment Engineering'', a monthly magazine, in March 1971 and discontinued it. In doing so, Cahners folded ''EEE's'' best features into ''EDN'', and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Addison Wesley
Addison-Wesley is an American publisher of textbooks and computer literature. It is an imprint of Pearson PLC, a global publishing and education company. In addition to publishing books, Addison-Wesley also distributes its technical titles through the O'Reilly Online Learning e-reference service. Addison-Wesley's majority of sales derive from the United States (55%) and Europe (22%). The Addison-Wesley Professional Imprint produces content including books, eBooks, and video for the professional IT worker including developers, programmers, managers, system administrators. Classic titles include ''The Art of Computer Programming'', ''The C++ Programming Language'', ''The Mythical Man-Month'', and ''Design Patterns''. History Lew Addison Cummings and Melbourne Wesley Cummings founded Addison-Wesley in 1942, with the first book published by Addison-Wesley being Massachusetts Institute of Technology professor Francis Weston Sears' ''Mechanics''. Its first computer book was ''Progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous Array Of Simple Processors
Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal with such events ** Async/await * Asynchronous system, a system having no global clock, instead operating under distributed control ** Asynchronous circuit, a sequential digital logic circuit not governed by a clock circuit or signal ** Asynchronous communication, transmission of data without the use of an external clock signal * Asynchronous cellular automaton, a mathematical model of discrete cells which update their state independently * Asynchronous operation, a sequence of operations executed out of time coincidence with any event Other uses * Asynchrony (game theory), when players in games update their strategies at different time intervals * Asynchronous learning, an educational method in which the teacher and student are separated in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gray Code
The reflected binary code (RBC), also known as reflected binary (RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit (binary digit). For example, the representation of the decimal value "1" in binary would normally be "" and "2" would be "". In Gray code, these values are represented as "" and "". That way, incrementing a value from 1 to 2 requires only one bit to change, instead of two. Gray codes are widely used to prevent spurious output from electromechanical switches and to facilitate error correction in digital communications such as digital terrestrial television and some cable TV systems. Motivation and name Many devices indicate position by closing and opening switches. If that device uses natural binary codes, positions 3 and 4 are next to each other but all three bits of the binary representation differ: : The problem with natural binary codes is that physical switches are not ideal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Source-synchronous
Source-Synchronous clocking refers to a technique used for timing symbols on a digital interface. Specifically, it refers to the technique of having the transmitting device send a clock signal along with the data signals. The timing of the unidirectional data signals is referenced to the clock (often called the strobe) sourced by the same device that generates those signals, and not to a global clock (i.e. generated by a bus master). Compared to other digital clocking topologies like system-synchronous clocks, where a global clock source is fed to all devices in the system, a source-synchronous clock topology can attain far higher speeds. This type of clocking is common in high-speed interfaces between micro-chips, including DDR SDRAM, SGI XIO interface, Intel Front Side Bus A front-side bus (FSB) is a computer communication interface (bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globally Asynchronous Locally Synchronous
Globally asynchronous locally synchronous (GALS), in electronics, is an architecture for designing electronic circuits which addresses the problem of safe and reliable data transfer between independent clock domains. GALS is a model of computation that emerged in the 1980s. It allows to design computer systems consisting of several synchronous islands (using synchronous programming for each such island) interacting with other islands using asynchronous communication, e.g. with FIFOs. Details A GALS circuit consists of a set of locally synchronous modules communicating with each other via asynchronous wrappers. Each synchronous subsystem ("clock domain") can run on its own independent clock (frequency). Advantages include much lower electromagnetic interference (EMI). The CMOS circuit (logic gates) requires relatively large supply current when changing state from 0 to 1. These changes are aggregated for synchronous circuit as most changes are initialised by an active clock edge. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastability (electronics)
In electronics, metastability is the ability of a digital electronic system to persist for an unbounded time in an unstable equilibrium or metastable state. In digital logic circuits, a digital signal is required to be within certain voltage or current limits to represent a '0' or '1' logic level for correct circuit operation; if the signal is within a forbidden intermediate range it may cause faulty behavior in logic gates the signal is applied to. In metastable states, the circuit may be unable to settle into a stable '0' or '1' logic level within the time required for proper circuit operation. As a result, the circuit can act in unpredictable ways, and may lead to a system failure, sometimes referred to as a "glitch". Metastability is an instance of the Buridan's ass paradox. Metastable states are inherent features of asynchronous digital systems, and of systems with more than one independent clock domain. In self-timed asynchronous systems, arbiters are designed to allow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
