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I want to calculate write, hold, and read the static noise margin of an SRAM block (WSNM, HSNM, and RSNM).

In order to do so, I want to write a command to do it, so I need to find the input voltage when its differentiation is equal to -1 for calculating VIL and VIH. Does anyone know the command for this?

enter image description here

enter image description here

Pictures are from the Analytical Review of Noise Margin in MVL: Clarification of a Deceptive Matter paper

ocrdu
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arsalan ghasemian
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  • Why use a noise margin figure defined for a stand alone inverter? Have a look at [W,H,R]SNM definitions in refs. https://corescholar.libraries.wright.edu/cgi/viewcontent.cgi?article=3146&context=etd_all (Figs. 42, 50, 52) and https://electronics.stackexchange.com/questions/343484/what-is-snmstatic-noise-margin-in-sram . – V.V.T Jul 15 '20 at 16:16
  • No,The image is just for represent VIL and VIH.and need of differentiation – arsalan ghasemian Jul 16 '20 at 11:55

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after some research, I found two ways in order to find when derivate of a parameter is -1. First way is using commands for example:

.MEAS dc vol find v(out) when deriv ('v(out)')=-1

It's just an example to show the syntax and based on your project the input and output nodes might be different.

The second way is to use CosmosScope or any other wave viewer application.

enter image description here

In this way using "point to point measurement" calculation of slope can be done graphically, but sometimes take some time to achieve proper response.

Best of luck

arsalan ghasemian
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