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In [[electrical engineering]], a '''shmoo plot''' is a graphical display of the response of a component or system varying over a range of conditions or inputs.
== Description==▼
Shmoo plots are often used to represent the results of the testing of complex electronic systems such as computers or integrated circuits such as [[DRAM]]s, ASICs or microprocessors. The plot usually shows the range of conditions in which the [[device under test]] operates (in adherence with some remaining set of specifications). ▼
For example, when testing [[semiconductor]] [[memory]]: [[voltage]]s, [[temperature]], and [[refresh rate]]s can be varied over specified ranges and only certain combinations of these factors will allow the device to operate. Plotted on independent axes (voltage, temperature, refresh rates), the range of working values will enclose a three-dimensional, usually oddly-shaped volume. Other examples of conditions and inputs that can be varied include [[frequency]], [[temperature]], timing parameters, system- or component-specific variables, and even varying knobs tweakable during [[silicon chip fabrication]] producing parts of varying quality which are then used in the process.▼
Often one 'knob' or variable is plotted on one axis against another knob or variable on another axis, producing a two-dimensional graph. This allows the test engineer to visually observe the operating ranges of the device under test. This process of varying the conditions and inputs to the component or system may sometimes be referred to as 'shmooing' but more officially known as electrical testing or qualification. [[Automatic test equipment]] often contains software features that allow automated shmooing of a part.▼
== Origin ==
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The plot takes its name from the [[Shmoo]], a fictional species created by [[Al Capp]] in the cartoon [[Li'l Abner]]. These small, blob-like creatures have shapes similar to the "working" volumes that would be enclosed by shmoo plots drawn against three independent variables (such as voltage, temperature, and response speed). Semiconductor chips do not usually exhibit "shmoo" shape plots. Historically, testing of magnetic core memory arrays produced the "shmoo" shape and the term continued into the semiconductor era.
▲== Description==
▲Shmoo plots are often used to represent the results of the testing of complex electronic systems such as computers or integrated circuits such as [[DRAM]]s, ASICs or microprocessors. The plot usually shows the range of conditions in which the [[device under test]] operates (in adherence with some remaining set of specifications).
▲For example, when testing [[semiconductor]] [[memory]]: [[voltage]]s, [[temperature]], and [[refresh rate]]s can be varied over specified ranges and only certain combinations of these factors will allow the device to operate. Plotted on independent axes (voltage, temperature, refresh rates), the range of working values will enclose a three-dimensional, usually oddly-shaped volume. Other examples of conditions and inputs that can be varied include [[frequency]], [[temperature]], timing parameters, system- or component-specific variables, and even varying knobs tweakable during [[silicon chip fabrication]] producing parts of varying quality which are then used in the process.
▲Often one 'knob' or variable is plotted on one axis against another knob or variable on another axis, producing a two-dimensional graph. This allows the test engineer to visually observe the operating ranges of the device under test. This process of varying the conditions and inputs to the component or system may sometimes be referred to as 'shmooing' but more officially known as electrical testing or qualification. [[Automatic test equipment]] often contains software features that allow automated shmooing of a part.
== Examples ==
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