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Questions about parameter calculation in Cell Library

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energeticdin

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Hi All,

In Cell libraries,
cell(INVX1) {
area : 3.14300;
pin(A) {
direction : Input
capacitance: 0.00225;
}
pin(Y) {
direction: output
capacitance: 0.0
internal_power() {
related_pin : "A";
rise_power(energy_template);
index_1 (xx, x, x, x,x,x)
index_2( );
values (
" 0.002417, x,x,x,x,x,xx", \
x
x
x
x x x x x x xx );
fall_power(energy_template) {

}
timing() {
cell_rise() {
index_1 { }
index_2 { }
values {
}
rise_transition()
cell_fall ()
fall_transiton ()

max_capacitance
cell_leakage_power:

My Doubt is:
1. How the area is calculated. I heard ther is def file. there will be X and Y. Onceit divide the values are coming, is it true.
2. How the tool is calculating the delay value.
3. I know index_1 is input transition time and index_2 is cap load.... what is that values .. which is having 7x7.
4. what is cell_rise, rise_transition, cell_fall and fall_transition
Plz clarify me

Thanks
DIN
 

onlymusic16

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Re: Reg: Cell Library

1. How the area is calculated. I heard ther is def file. there will be X and Y. Onceit divide the values are coming, is it true.

---> Area is calculated from LEF file, find out more on LEF file(it contains the physical info about the std cells and metal layers.


2. How the tool is calculating the delay value.

---> The tool employs its algorithmic equations, in short its basically interpolation algorithm.


3. I know index_1 is input transition time and index_2 is cap load.... what is that values .. which is having 7x7.

---> Imagine you are doing matrix multiplication(row matrix * column matrix). The slew Vs Load matrix results in Delay matrix(probably resulting 7x7 but can change with the slew/load matrix getting changed)


4. what is cell_rise, rise_transition, cell_fall and fall_transition

---> Imagine an inverter. Give it an input rising transition(low to high), your output is going to fall(high to low) after some delay(cell_fall) with fall_transition(80%-20% of vdd). Similarly for a falling transition at the input, you will get the other two matrix tables.


Hope this helps.
 

energeticdin

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Re: Reg: Cell Library

Hi
Thanks yaar.
Then, I find fall_power(energy_template) {
}
what is this for?again same index_1 and index_2 is also ther....

In Cell library, I also find cell_leakage_power: 18054.2324
What do u mean by this....

Then I opened LEF file... There i seen how they are calculating Area.
I seen ther, MACRO INVX1
SIZE 0.920 BY 3.690 --- When i multiplied this i get area..
SYMMETRY X Y
SITE XXXX;
PIN Y
DIRECTION OUTPUT;
PORT
LAYER METAL1;
RECT 0.333 1.103 0.324 0.233
RECT
RECT
RECT
END
ANTENNADIFFAREA 0.423
ENDY
PIN A
again same repeation...

What do u mean by this... what r the things we have to see here....
Then is ther any PDF to understand the Cell libraries completely...
Plz tell me some links or PDF ....

I am very thankful to u

Thanks
DIN
 

onlymusic16

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Re: Reg: Cell Library

express your thanks by pressing 'helped me' button:|

If you want to know more regarding LEF and its syntax, you should first try to search within edaboard.com. With its huge database, i am pretty sure you will find more on LEF.

Still if you are not able to access any document, I will post some docs.

Regarding your questions on the lib files, I would suggest you to read the Liberty user guide first. I have seen it here on eda upload/download section.

Then, I find fall_power(energy_template) {
}
what is this for?again same index_1 and index_2 is also ther....

----> As explained earlier, you can expect some change in the output and if the output is going low (high to low) you will have fall_power tables( this is dynamic power)

Let me know incase you want to know more on this.
 

bharatesh7

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Re: Reg: Cell Library

express your thanks by pressing 'helped me' button:|

If you want to know more regarding LEF and its syntax, you should first try to search within edaboard.com. With its huge database, i am pretty sure you will find more on LEF.

Still if you are not able to access any document, I will post some docs.

Regarding your questions on the lib files, I would suggest you to read the Liberty user guide first. I have seen it here on eda upload/download section.

Then, I find fall_power(energy_template) {
}
what is this for?again same index_1 and index_2 is also ther....

----> As explained earlier, you can expect some change in the output and if the output is going low (high to low) you will have fall_power tables( this is dynamic power)

Let me know incase you want to know more on this.





Hi i need to know that is it dynamic power or static power. because here output wont toggle for applied input so it is internal_power dissipation of cell.Please correct me if am wrong.
 

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