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What does the Σ sign mean in electronics?

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Could you provide an example from where this is used? – chwi Dec 6 '12 at 12:31
Context! If it's a greek datasheet it's the capital letter "S" – Federico Russo Feb 6 '13 at 10:10
up vote 0 down vote accepted

Sigma = summation of signals.... It can also mean to subtract signals if the sign in negative for 1 of the signals http://www.freepatentsonline.com/6920182-0-large.jpg

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Sigma is reserved for Sum or summation or the summing point.

It often used with the inverting input of Op Amps as each resistor value controls the weighting value of gain for each input. However in the symbolic schematic it may be the + or - depending on how it is configured.

This method is commonly used in Signal Delta ADC's so that the difference is quantized on each sample for high speed , high resolution analog to digital conversion. The difference is then added (summed) to previous digital result.

These schematics are some examples of the use of Sigma.

enter image description here zoom

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Where did you find that image? – Garrett Fogerlie Dec 6 '12 at 8:32
I made it from Google images – Tony Stewart Dec 6 '12 at 9:25

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