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 Calculating IC parameters using layout dimensions. 

Last post Sun, Oct 20 2013 9:45 AM by Andrew Beckett. 1 replies.
Started by ChelseaFC 20 Oct 2013 04:46 AM. Topic has 1 replies and 1883 views
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  • Sun, Oct 20 2013 4:46 AM

    • ChelseaFC
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    • Joined on Sun, Oct 20 2013
    • Posts 1
    • Points 20
    Calculating IC parameters using layout dimensions. Reply

    Hello everyone,

    This is my first post, so please bear with me. Hopefully, we all can learn something here.

    I am a student of Electrical Engineering, and i working on a small research project. For the starters, i have been given an assignment in which i am suppose to find the parameters of an INVERTER that was fabricated using the cadence layout tool. But, the problem is that i have been taught how to find parameters using the circuit layout (using voltages and currents), not the fabrication layout (using fabrication dimensions).
    All i have been given to do so is a print out of the layout, and the dimensions of different layers (Polysilicon, metal 1, metal 2 e.t.c.)
    So my question is, is it even possible to calculate the parameters using JUST the dimensions of the layers? and if yes, what text should i read to find any equations or formulas that i need.
    I just can not comprehend how it is possible to find the parameters of an INVERTER, just with the use of a print out of layout and the dimensions (Lambda) of the layers?

    I am not asking for spoon feeding, i really just don't know where to even start. So, any leads would be really helpful.

    Thank you. 

    • Post Points: 20
  • Sun, Oct 20 2013 9:45 AM

    Re: Calculating IC parameters using layout dimensions. Reply

    I think you might be best served asking your supervisor. You don't say what "parameters" you are talking about? Normally for MOS transistors, the parameters that are given to an instance are physical dimensions, and then the device model takes these physical dimensions and models the behaviour of the device with those dimensions. The physical dimensions will include things like the width and length of the gate (the poly over diffusion), the area and perimeter of the drain and source regions, plus some additional parameters often used in small geometries to represent length-of-diffusion effects, well proximity effects and so on. 

    When starting from a schematic, estimates are used for many of these parameters, based on the entered width and length of the devices. Once you have the layout, you can use an LVS and Extraction tool to extract the real physical dimensions for the device, together with (potentially) parasitic resistances, capacitances (and maybe inductances, although I doubt you'd need to for an inverter) - and then you can resimulate the design with these more realistic measurements.

    Does that help? Your question was a bit open, so I thought I'd try to give you some pointers, but since I don't know what you do and don't know, it might be that I'm teaching granny to suck eggs.

    Regards,

    Andrew.

    • Post Points: 5
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Started by ChelseaFC at 20 Oct 2013 04:46 AM. Topic has 1 replies.