Core_EDA

# EM analysis in VP

## EM calculation 

### debug level policy

Please follow the IR process and output debug message according to levels□ Usage□set_app_var em em_debug 20

debug 0 (not set param): nothing will happen;

debug < 10: will print flow message: (such as "START: xxx" and "FND: xxx"  debug < 20: will print driver current calculate information□

debug >= 20 : will print segments current/limit—current calculate information□ debug = 100 : will print detail message, only for RD can know code function□

### AVG EM limit current

VP calculate average EM limit current related parameters:

set—app—var em half—node—scale—factor 0.9 set—app—var em temperature—em 110

DC limit current = polymonial_current_cal * temp_rating_factor

![](clipboard-202503292308-tsb5q.png)

To calculation average EM limit current, EM rule based on length and width. For each shape, avg length are sum of block length, and multiplied by half node scale.

avg length: (0.695+0.05+1.4+0.05+2.21) * 0.9 = 3.9645 nm

For width, using each shape width, and multiplied by half node scale. width: 0.05 * 0.9 = 0.045 nm

temp_rating_factor table: (based on .itf or .ircx)

![](clipboard-202503292309-f6rei.png)

VP [add_em_rule_advance] DC rule demo:

When got avg length and width, can lookup polynomial table and calculated polynomial based results. Lookup temp_rating_factor table got temperature factor set by parameter.

**DC limit current = polymonial_current_cal * temp_rating_factor**

髻髻 For l-ayer AVG FM rule

add—em—rule—advance -measure dc -mask—num 1 -polynomial "switch

{

case 1 > 4.5 and w< 0.09 : 1.2 * 0.605000 * (W - 0.003);

case 1 > 4.5 and w >= 0.09 : 2.4* 0.605000 * (W- 0.003);

case 1 <= 4.5 : 4.8 * 0.605000 * ( W - 0.003 );

default: -1;

}" \

-temp—rating factor "Switch

{

case TFMPFRAT..RF FM == 85: 5.066;  case TFMPFRAT..RF FM == 105: 2.293;  case TFMPFRAT..RF FM == 110: 1.599;  case TFMPFRAT..RF FM == 125: 1.0;  case TFMPFRAT..RF FM == 150: 0.212;

default: -1;

}

## PEAK EM limit current

VP calculate Peak EM limit current related parameters:

set—app—var em half—node—scale—factor 0.9

set—app—var em em—peak—source—equation—techfile false

When em_peak_source_equation_techfile == true Peak limit current = polymonial_current_cal When em_peak_source_equation_techfile == false

Peak limt current = polymonial_current_cal * [1/sqrt(r)]

VP [add_em_rule_advance] PEAK rule demo:

w: width (half node scale) td: pulse width

r: duty ratio

髻髻 For l-ayer PFAK FM rule

add—em—rule—advance -measure peak -mask—num 1 -polynomial "switch

{

case w > 0.18 and td >= 0.5 : 26.8 * (w -0.003); case w<0.135 and td>=0.5:53.6*(w - 0.003);

case w>= 0.135 and w <= 0.18 and td >= 0.5 : 42.88 * (w - 0.003);

case w > 0.18 and td < 0.5 and td >= 0.001 and r >= 0.05 : 26.8 * (w - 0.003) / sqrt(r); case w <0

.135 and td <0.5 and td >= 0.001 and r >= 0.05 : 53.6 * (w - 0.003) / sqrt(r);

case w>= 0.135 and w <=0.18 and td< 0.5 and td >= 0.001 and r >= 0.05 : 42.88 * (w - 0.003) / sqrt

(r); case w > 0.18 and td < 0.5 and td >= 0.001 and r < 0.05 : 26.8 * (w - 0.003) / sqrt(0.05);

...

more information in Part 2 "Advance FM rule format" 

## RMS EM limit current

VP calculate RMS EM limit current related parameters:

set—app—var em half—node—scale—factor 0.9 set—app—var em em—rms—metal—line—no 3 set—app—var em average—option false

RMS_current_limit = polynomial_current_cal * spacing_factor * rating_factor

Rating factor:

N (metal line number) For 28nm N=3

rating factor table:

![](clipboard-202503292311-c1drg.png)

via-via spacing factor:

S (via-via spacing)

Related param: set_app_var em average_option false

![](clipboard-202503292312-rt535.png)

When shape no down vias, didn't consider spacing factor.

![](clipboard-202503292312-5eg3e.png)

via-via spacing using signal actually direction, sum of those distance and half node scale also used. 

via-via spacing: (0.03+0.575+0.1+1.35+0.1+2.09+0.03) * 0.9 = 3.8475

![](clipboard-202503292312-pg1wn.png)

VP [add_em_rule_advance] RMS rule demo:

When got N and S, then lookup via_via_spacing_factor and metal_line_no_rating_factor table to got factor. RMS_current_limit = polynomial_current_cal * spacing_factor * rating_factor

髻髻 For l-ayer RMS FM rule

add—em—rule—advance -measure rms -mask—num 1 -polynomial "Switch

{

default : sqrt ( 19.ll * delta—T * ( w - 0.003) " 2 * ( w - 0.003 + 0.264) / ( w - 0.003 + 0.0443 

));

}" \

-via—via—spacing—factor "switch

{

case s >= 9 and AVFRAGF—OPTION == false : 1.0; case s >= 9 and AVFRAGF OPTION == true : 1.2; case s > 2.l and s <9: 1.05;

case s > 0.9 and s <= 2.l: 1.3; case s > 0.2l and s <= 0.9: 2.0; case s <= 0.2l: 2.2;

default: -1;

}" \

-metal line no rating factor "switch case n >= 9: 1.0;

case n >= 5 and n <9: 1.05; case n >= 3 and n < 5: 1.32; case n >= 1 and n < 3: 1.5; default: -1;

}" 

## PEAK current [TBD] 

## RMS current [TBD] 

## AVG current [TBD]

More detail: attachment:"EM_calculation.pptx"

## Advance EM rule format

髻髻髻 advanced FM rule sample

髻髻 For l-ayer PFAK FM rule

add—em—rule—advance -measure peak -mask—num 1 -polynomial "switch

{

case w > 0.18 and td >= 0.5 : 26.8 * (w -0.003); case w<0.135 and td>=0.5:53.6*(w - 0.003);

case w>= 0.135 and w <= 0.18 and td >= 0.5 : 42.88 * (w - 0.003);

case w > 0.18 and td < 0.5 and td >= 0.001 and r >= 0.05 : 26.8 * (w - 0.003) / sqrt(r); case w <0

.135 and td <0.5 and td >= 0.001 and r >= 0.05 : 53.6 * (w - 0.003) / sqrt(r);

case w>= 0.135 and w <=0.18 and td< 0.5 and td >= 0.001 and r >= 0.05 : 42.88 * (w - 0.003) / sqrt

(r); case w > 0.18 and td < 0.5 and td >= 0.001 and r < 0.05 : 26.8 * (w - 0.003) / sqrt(0.05);

case w < 0.135 and td < 0.5 and td >= 0.001 and r < 0.05 : 53.6 * (w - 0.003) / sqrt(0.05);

;

case w < 0.135 and td < 0.001 and td >= 0.0001 and r >= 0.05 : l5.04 * (w - 0.003) / sqrt(r);

case w >= 0.135 and w <= 0.18 and td < 0.001 and td>=0.0001 and r>=0.05:60.02 * (w - 0.003) / sqrt (r); case w> 0.18 and td < 0.001 and td >= 0.0001 and r<0.05 :3l.52 * (w - 0.003) / sqrt(0.05); case w < 0.135 and td < 0.001 and td >= 0.0001 and r < 0.05 : l5.04 * (w - 0.003) / sqrt(0.05); case w >= 0.135 and w <= 0.18 and td < 0.001 and td >= 0.0001 and r < 0.05 : 60.02 * (w - 0.003) /

 sqrt(0.05); case w>0.18 and td <0.0001 and r >=0.05 :3l.52 * (w - 0.003) / sqrt(r); case w<0.135 and td < 0.0001 and r >= 0.05 : l5.04 * (w - 0.003) / sqrt(r);

case w >= 0.135 and w <= 0.18 and td < 0.0001 and r >= 0.05 : 60.02 * (w - 0.003) / sqrt(r); case  w> 0.18 and td < 0.0001 and r<0.05:53.60 *(w-0.003) / sqrt(0.05);

case w <0.135 and td < 0.0001 and r <0.05 :10l.20 * (w-0.003) / sqrt(0.05);

case w >= 0.135 and w <= 0.18 and td < 0.0001 and r < 0.05 : 85.l6 * (w - 0.003) / sqrt(0.05);  default: -1;

}

髻髻 For l-ayer AVG FM rule

add—em—rule—advance -measure dc -mask—num 1 -polynomial "switch

{

case 1 > 4.5 and w< 0.09 : 1.2 * 0.605000 * (W - 0.003);

case 1 > 4.5 and w >= 0.09 : 2.4* 0.605000 * (W- 0.003);

case 1 <= 4.5 : 4.8 * 0.605000 * ( W - 0.003 );

default: -1;

}" \

-temp—rating factor "Switch

{

case TFMPFRAT..RF FM == 85: 5.066;  case TFMPFRAT..RF FM == 105: 2.293;  case TFMPFRAT..RF FM == 110: 1.599;  case TFMPFRAT..RF FM == 125: 1.0;  case TFMPFRAT..RF FM == 150: 0.212;

default: -1;

}

髻髻 For l-ayer RMS FM rule

add—em—rule—advance -measure rms -mask—num 1 -polynomial "Switch

{

default : sqrt ( 19.ll * delta—T * ( w - 0.003) " 2 * ( w - 0.003 + 0.264) / ( w - 0.003 + 0.0443 

));

}" \

-via—via—spacing—factor "switch

{

case s >= 9 and AVFRAGF—OPTION == false : 1.0; case s >= 9 and AVFRAGF OPTION == true : 1.2; case s > 2.l and s <9: 1.05;

case s > 0.9 and s <= 2.l: 1.3; case s > 0.2l and s <= 0.9: 2.0; case s <= 0.2l: 2.2;

default: -1;

}" \

-metal line no rating factor "switch case n >= 9: 1.0;

case n >= 5 and n <9: 1.05; case n >= 3 and n < 5: 1.32; case n >= 1 and n < 3: 1.5; default: -1;

}" 

## EM analysis reference flow

髻髻髻 FM analysis reference flow

髻 Input design data source config.tcl

髻 Setup design

compose—top—design �top—def �blk—def �tf—file �lefl-ist set—link—path �libl-ist

import—liberty -all—linkpath �liblist

link—prollect

髻 Setting FM param and input FM rule set—app—var em half—node—scale—factor 0.9 set—app—var em em—rms—metal—line—no 3 set—app—var em average—option true

set—app—var em em—peak—source—equation—techfile true set—app—var em temperature—em 110

set—app—var em em—recovery—factor 0.9 set—app—var em em—rms—delta t 5 set—app—var em em—mode "RK" 

source �em—file

髻 Input rlc

purge—rlc—model [lindex [list—rlc—model]0] source �rlc—file

set—parasitic—condition  �rlc—name

髻 Input SPFF

set—app—var lpe force—wire—type 3            髻 import—parasitics �spef—file

import—parasitics -module—rc—file �spef—cfg

髻 source -echo �ploc

髻 Input twf file, got timing information  import—twf -module—twf—file XXX.twf—cfg report—twf

update—twf -default—transition 0.1 -missing—period 0.5

髻   Set   SWA   info set—switching—activity -clear

set—switching—activity -clock—net -number—of—toggles 2 -period—of—clock 2 set—switching—activity -signal—net -number—of—toggles 0.15 -period—of—clock 2

report—power—analysis

髻 Report PFAK/DC/RMS signal em 

report—signal—em -mode peak 

report—signal—em -mode avg 

report—signal—em -mode rms

## Debug method (From Lin Gu)

可以选中net，叩Dexport单条netD息□export_def  -routing  -object  [get_sel]，翻net连叩的instD息叩DexportDdefD