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Iddq Testing
Iddq testing is a method for testing CMOS integrated circuits for the presence of manufacturing faults. It relies on measuring the supply current (Idd) in the quiescent state (when the circuit is not switching and inputs are held at static values). The current consumed in the state is commonly called Iddq for Idd (quiescent) and hence the name. Iddq testing uses the principle that in a correctly operating quiescent CMOS digital circuit, there is no static current path between the power supply and ground, except for a small amount of leakage. Many common semiconductor manufacturing faults will cause the current to increase by orders of magnitude, which can be easily detected. This has the advantage of checking the chip for many possible faults with one measurement. Another advantage is that it may catch faults that are not found by conventional stuck-at fault test vectors. Iddq testing is somewhat more complex than just measuring the supply current. If a line is shorted to Vdd, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integrated Circuits
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny MOSFETs (metal–oxide–semiconductor field-effect transistors) integrate into a small chip. This results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete electronic components. The IC's mass production capability, reliability, and building-block approach to integrated circuit design has ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world of electronics. Computers, mobile phones and other home appliances are now inextricable parts of the structure of modern societies, made possible by the small size and low cost of ICs such as modern compute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. CMOS technology is used for constructing integrated circuit (IC) chips, including microprocessors, microcontrollers, memory chips (including CMOS BIOS), and other digital logic circuits. CMOS technology is also used for analog circuits such as image sensors (CMOS sensors), data converters, RF circuits (RF CMOS), and highly integrated transceivers for many types of communication. The CMOS process was originally conceived by Frank Wanlass at Fairchild Semiconductor and presented by Wanlass and Chih-Tang Sah at the International Solid-State Circuits Conference in 1963. Wanlass later filed US patent 3,356,858 for CMOS circuitry and it was granted in 1967. commercialized the technology with the trademark "COS-MO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic Gate
A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and unlimited fan-out, or it may refer to a non-ideal physical device (see Ideal and real op-amps for comparison). Logic gates are primarily implemented using diodes or transistors acting as electronic switches, but can also be constructed using vacuum tubes, electromagnetic relays (relay logic), fluidic logic, pneumatic logic, optics, molecules, or even mechanical elements. Now, most logic gates are made from MOSFETs (metal–oxide–semiconductor field-effect transistors). With amplification, logic gates can be cascaded in the same way that Boolean functions can be composed, allowing the construction of a physical model of all of Boolean logic, and therefore, all of the algorithms and mathem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiconductor Manufacturing
Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuit (IC) chips such as modern computer processors, microcontrollers, and memory chips such as NAND flash and DRAM that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photolithographic and chemical processing steps (such as surface passivation, thermal oxidation, planar diffusion and junction isolation) during which electronic circuits are gradually created on a wafer made of pure semiconducting material. Silicon is almost always used, but various compound semiconductors are used for specialized applications. The entire manufacturing process takes time, from start to packaged chips ready for shipment, at least six to eight weeks (tape-out only, not including the circuit design) and is performed in highly specialized semiconductor fabrication plants, also called foundries or fabs. All fabrication takes place inside a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stuck-at Fault
A stuck-at fault is a particular fault model used by fault simulators and automatic test pattern generation (ATPG) tools to mimic a manufacturing defect within an integrated circuit. Individual signals and pins are assumed to be ''stuck'' at Logical '1', '0' and 'X'. For example, an input is tied to a logical 1 state during test generation to assure that a manufacturing defect with that type of behavior can be found with a specific test pattern. Likewise the input could be tied to a logical 0 to model the behavior of a defective circuit that cannot switch its output pin. Not all faults can be analyzed using the stuck-at fault model. Compensation for static hazards, namely branching signals, can render a circuit untestable using this model. Also, redundant circuits cannot be tested using this model, since by design there is no change in any output as a result of a single fault. Single stuck at line Single stuck line is a fault model used in digital circuits. It is used for p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Test Vector
In computer science and engineering, a test vector is a set of inputs provided to a system in order to test that system. In software development, test vectors are a methodology of software testing and software verification and validation. Rationale In computer science and engineering, a system acts as a computable function. An example of a specific function could be y = f(x) where y is the output of the system and x is the input; however, most systems' inputs are not one-dimensional. When the inputs are multi-dimensional, we could say that the system takes the form y = f(x_1, x_2, ...) ; however, we can generalize this equation to a general form Y = C(X) where Y is the result of the system's execution, C belongs to the set of computable functions, and X is an input vector. While testing the system, various test vectors must be used to examine the system's behavior with differing inputs. Example For example, consider a login page with two input fields: a username field and a pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Controllability
Controllability is an important property of a control system, and the controllability property plays a crucial role in many control problems, such as stabilization of unstable systems by feedback, or optimal control. Controllability and observability are dual aspects of the same problem. Roughly, the concept of controllability denotes the ability to move a system around in its entire configuration space using only certain admissible manipulations. The exact definition varies slightly within the framework or the type of models applied. The following are examples of variations of controllability notions which have been introduced in the systems and control literature: * State controllability * Output controllability * Controllability in the behavioural framework State controllability The state of a deterministic system, which is the set of values of all the system's state variables (those variables characterized by dynamic equations), completely describes the system at any give ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observability
Observability is a measure of how well internal states of a system can be inferred from knowledge of its external outputs. In control theory, the observability and controllability of a linear system are mathematical duals. The concept of observability was introduced by the Hungarian-American engineer Rudolf E. Kálmán for linear dynamic systems. A dynamical system designed to estimate the state of a system from measurements of the outputs is called a state observer or simply an observer for that system. Definition Consider a physical system modeled in state-space representation. A system is said to be observable if, for every possible evolution of state and control vectors, the current state can be estimated using only the information from outputs (physically, this generally corresponds to information obtained by sensors). In other words, one can determine the behavior of the entire system from the system's outputs. On the other hand, if the system is not observable, there ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scan Chain
Scan chain is a technique used in design for testing. The objective is to make testing easier by providing a simple way to set and observe every flip-flop in an IC.The basic structure of scan include the following set of signals in order to control and observe the scan mechanism. #Scan_in and scan_out define the input and output of a scan chain. In a full scan mode usually each input drives only one chain and scan out observe one as well. #A scan enable pin is a special signal that is added to a design. When this signal is asserted, every flip-flop in the design is connected into a long shift register. #Clock signal which is used for controlling all the FFs in the chain during shift phase and the capture phase. An arbitrary pattern can be entered into the chain of flip-flops, and the state of every flip-flop can be read out. In a full scan design, automatic test pattern generation (ATPG) is particularly simple. No sequential pattern generation is required - combinatorial test ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System On Chip
A system on a chip or system-on-chip (SoC ; pl. ''SoCs'' ) is an integrated circuit that integrates most or all components of a computer or other electronic system. These components almost always include a central processing unit (CPU), memory interfaces, on-chip input/output devices, input/output interfaces, and secondary storage interfaces, often alongside other components such as radio modems and a graphics processing unit (GPU) – all on a single substrate or microchip. It may contain digital, analog, mixed-signal, and often radio frequency signal processing functions (otherwise it is considered only an application processor). Higher-performance SoCs are often paired with dedicated and physically separate memory and secondary storage (such as LPDDR and Universal Flash Storage, eUFS or eMMC, respectively) chips, that may be layered on top of the SoC in what's known as a package on package (PoP) configuration, or be placed close to the SoC. Additionally, SoCs may use s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moore's Law
Moore's law is the observation that the number of transistors in a dense integrated circuit (IC) doubles about every two years. Moore's law is an observation and projection of a historical trend. Rather than a law of physics, it is an empirical relationship linked to gains from experience in production. The observation is named after Gordon Moore, the co-founder of Fairchild Semiconductor and Intel (and former CEO of the latter), who in 1965 posited a doubling every year in the number of components per integrated circuit, and projected this rate of growth would continue for at least another decade. In 1975, looking forward to the next decade, he revised the forecast to doubling every two years, a compound annual growth rate (CAGR) of 41%. While Moore did not use empirical evidence in forecasting that the historical trend would continue, his prediction held since 1975 and has since become known as a "law". Moore's prediction has been used in the semiconductor industry to g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Gating
Power gating is a technique used in integrated circuit design to reduce power consumption, by shutting off the current to blocks of the circuit that are not in use. In addition to reducing stand-by or leakage power, power gating has the benefit of enabling Iddq testing. Overview Power gating affects design architecture more than clock gating. It increases time delays, as power gated modes have to be safely entered and exited. Architectural trade-offs exist between designing for the amount of leakage power saving in low power modes and the energy dissipation to enter and exit the low power modes. Shutting down the blocks can be accomplished either by software or hardware. Driver software can schedule the power down operations. Hardware timers can be utilized. A dedicated power management controller is another option. An externally switched power supply is a very basic form of power gating to achieve long term leakage power reduction. To shut off the block for small intervals of ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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