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Parametric Length in Cadence Schematic and Layout

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april1975

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Hello
I have designed a schematic in Cadence composer scematic. I have specified parametric length and width for various nmos and pmos transistors in it. I have analysed the circuit with analog environment. It works. Now I want to design layout of the circuit, I can't generate the layout directly from the schematic, because the length and width are not specified. Is there any way for specifying parametric length in schematic?
april
 

erikl

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I have designed a schematic in Cadence composer scematic. I have specified parametric length and width for various nmos and pmos transistors in it.
Is there any way for specifying parametric length in schematic?
Seems you already found the solution!?
 

april1975

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erikl wrote:
Seems you already found the solution!?
yes. In Analog Design Environment, we must add a variable for the length and specify its value. But we can`t generate a layout from the schematic. Because value f length is needed.
 

erikl

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Sure. But you can still change the length l (and the width w) of individual layout Pcells.
BTW: the parameter f describes the number of fingers in schematics.
 

april1975

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But now, i think about layout of nmos or pmos transistors in which:
m>1 & fingers>1
How i must draw nwell or pwell? Must nwell be detached for a transistor with separate bulk and source?
How i must path between various part of a transistor?
Do you have any image of layouts for it?
 

erikl

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But now, i think about layout of nmos or pmos transistors in which: m>1 & fingers>1
For f>1 I think you can use Pcell layout generation. For m>1 you have to parallel m transistors.

How i must draw nwell or pwell? Must nwell be detached for a transistor with separate bulk and source?
This actually is layout basics. Read the relevant books, e.g. Alan Hastings "The ART of ANALOG LAYOUT".

How i must path between various part of a transistor?
By poly (short distances only), M1 and (if necessary) M2 .

Do you have any image of layouts for it?
You can find a lot of layout images in this forum, or in G00GLE images.
 
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