JCUI Marvell

Monday, October 25, 2010

set_noise_margin

-----Original Message-----
From: Jeffrey H Cui [mailto:jeffrey@marvell.com]
Sent: Monday, October 25, 2010 6:25 PM
To: Jeffrey Cui
Subject:

2. Synopsys Commands Command Reference
set_noise_margin

NAME
set_noise_margin
Sets noise margin for a library pin, port, or pin.

SYNTAX
int set_noise_margin
[-above]
[-below]
[-low]
[-high]
margin_value
object_list

float margin_value
list object_list

ARGUMENTS
-above Specifies the noise margin for above ground or power rail noise
analysis region.

-below Specifies the noise margin for below ground or power rail noise
analysis region.

-low Specifies the noise margin for ground rail noise.

-high Specifies the noise margin for power rail noise.

margin_value
Specifies a margin value. The value is the input height in
units of voltage. 1.0.

object_list
Specifies a list of lib-pins or ports.

DESCRIPTION
Each library cell input can tolerate a certain amount of noise without
causing a failure at the cell output. This characteristic is called
noise immunity. This command specifies noise immunity at library pins
to determine whether noise failures occur as well as the amount of
noise slack.

Noise immunity in the library can be specified as noise immunity
curves, polynomials, or tables or in terms of noise margins.

This command specifies a noise margin for a library pin, design port,
or pin. It can be used in the absence of library-specified noise immu-
nity characteristics, or to override the library-specified characteris-
tics by replacing them with noise margins. Noise immunity curves that
have been annotated using the set_noise_immunity_curve command will
override noise margins set by this command.

Noise margins consider only the bump heights at the cell inputs. Using
height-only noise margins is simpler, faster, and more conservative
than the other methods.

For high, narrow noise bumps, using height-only noise margins is pes-
simistic because it treats some bumps as noise failures that would oth-
erwise pass with the immunity curve model. However, for wide noise
bumps, using noise
margins gives the same results as using noise immunity curves.

Noise immunity characteristics can vary for different noise bump types,
so there can be four different noise margins associated with each
input: below low, above low, below high, and above high. All values are
specified as positive numbers for all four types of noise bumps.

In the absence of command-specified or library-specified noise immunity
data, PrimeTime SI calculates the maximum allowable noise bump heights
based on DC noise margins of the driver and receiver, as defined in the
.lib technology library by the input/output logic-level parameters.

report_noise_calculation will show whether noise margin information was
taken from the library or annotated by this command.

EXAMPLES
This example specifies a margin of 4 for above the ground rail noise
for pin A of library cell IV in the lsi_10k library:

pt_shell> set_noise_margin -above -low 4 lsi_10k/IV/A

SEE ALSO
set_noise_immunity_curve (2), report_noise_calculation (2),
remove_noise_margin (2).

set_noise_margin -above -low 4 m9hpd_std_slow/hpd_sao21bx2/A2

set_noise_immunity_curve

-----Original Message-----
From: Jeffrey H Cui [mailto:jeffrey@marvell.com]
Sent: Monday, October 25, 2010 6:25 PM
To: Jeffrey Cui
Subject:

2. Synopsys Commands Command Reference
set_noise_immunity_curve

NAME
set_noise_immunity_curve
Sets noise immunity curve for a library pin or port.

SYNTAX
int set_noise_immunity_curve
[-above]
[-below]
[-low]
[-high]
[-height height_value]
[-width width_value]
[-area area_value]
object_list

float height_value
float width_value
float area_value
list object_list

ARGUMENTS
-above Specifies an immunity curve for above ground or power rail noise
analysis region.

-below Specifies an immunity curve for below ground or power rail noise
analysis region.

-low Specifies an immunity curve for ground rail noise.

-high Specifies an immunity curve for power rail noise.

-height height_value
Specifies the height of the input voltage bump at the threshold
of logic failure. The height is in the voltage units of the
library.

-width width_value
Specifies the width of the input voltage bump at the threshold
of logic failure. The width is in the time units of the
library.

-area area_value
Specifies an area value for the curve. This parameter specifies
the size of the hyperbolic curve. 1.0.

object_list
Specifies a list of lib-pins or ports.

DESCRIPTION
Each cell input can tolerate a certain amount of noise without causing
a failure at the cell output. This characteristic is called noise immu-
nity. This command specifies noise immunity at library pins to deter-
mine whether noise failures occur as well as the amount of noise slack.

Noise immunity in the library can be specified as noise immunity
curves, polynomials, or tables or in terms of noise margins that con-
sider only the bump heights at the cell inputs.

This command specifies a noise immunity curve for a library pin or
design port. It can be used in the absence of library-specified noise
immunity characteristics, or to override the library-specified charac-
teristics by replacing them with a noise immunity curve. This command
will also override noise margins that have been annotated using the
set_noise_margin command,

The curve is hyperbolic with three coefficients to fully specify the
hyperbola: height and width of the input voltage bump at the threshold
of logic failure, and an area value to specify the size of the curve.
The three coefficients should be chosen to match the hyperbolic curve
to the data points obtained by laboratory characterization.

Noise immunity characteristics can vary for different noise bump types,
so there can be four different noise immunity curves associated with
each input: below low, above low, below high, and above high. All coef-
ficients are specified as positive numbers for all four types of noise
bumps.

report_noise_calculation will show whether noise immunity information
was taken from the library or annotated by this command.

EXAMPLES
This example specifies a noise height of 2, width of 3, area of 4 for
above the ground rail noise for pin A of library cell IV in the lsi_10k
library:

pt_shell> set_noise_immunity_curve -above -height 2 -width 3 \
-area 4 lsi_10k/IV/A

SEE ALSO
set_noise_margin (2), report_noise_calculation (2), remove_noise_immu-
nity_curve (2).

si_noise_composite_aggr_mode

NAME
   si_noise_composite_aggr_mode
   Specifies the composite aggressor mode for noise analysis.

TYPE
   String

DEFAULT
   disabled

DESCRIPTION
   This variable specifies which composite aggressor mode is used in
   PrimeTime SI noise analysis. Allowed values are disabled (the
   default), which turns off the composite aggressor feature. normal,
   causes PrimeTime SI to calculate noise by utilizing the non-statistical
   composite aggressor feature. Selecting statistical causes PrimeTime SI
   to calculate noise by using the statistical composite aggressor flow.

   In disabled composite aggressor mode, PrimeTime SI uses its original
   flow with composite aggressor completely off to analyze the noise.

   In normal composite aggressor mode, PrimeTime SI aggregates the effect
   of multiple small aggressors into a single composite aggressor, thereby
   reducing the computational complexity and improving the performance.

   statistical composite aggressor mode reduces the pessimism for noise
   analysis by reducing the effect of composite aggressor.

   For the current value of this variable, type printvar si_noise_compos-
   ite_aggr_mode.

si_xtalk_double_switching_mode

NAME
   si_xtalk_double_switching_mode
   Controls the double switching detection during the PrimeTime-SI
   timing analysis.

TYPE
   String

DEFAULT
   "disabled"

DESCRIPTION
   Double switching detection mode can have one of these three values,
   "disabled", "clock_network" or "full_design". When this mode is "dis-
   abled", the default mode, this double switching detection is not
   enabled. When this variable is enabled (set to "clock_network" or
   "full_design"), during update_timing PrimeTime-SI checks that whether
   crosstalk bump on the switching victim could cause the output to switch
   twice (and cause a pulse) instead of of desiered single signal propaga-
   tion.

   To detect the potential double switching in the clock network, which
   could cause the double clocking (where the clock could switch twice on
   a the sensitive edge) or false clocking (where the switching bump on
   the non-sensitive edge could actually latch the state), set this value
   to "clock_network".

   To detect the potential double switching in the data path as well as
   clock path set this variable to "full_design". Double switching on a
   data path is less severe then double switching on the clock network.

   The double switching detection needs CCSN library information on the
   victim load cell.

   After the update_timing user could access these information in two ways
   1) by command report_si_double_switching or 2) by the net attributes
   si_has_double_switching & si_double_switching_slack. Refer the man
   page of report_si_double_switching for the command details. The victim
   net attribute si_has_double_switching is true when ever there is a
   potential double switching on any of the load pins. The victim net
   attribute si_double_switching_slack has the bump slack, reducing the
   switching bump by that much amount could remove the double switching.
   If the victim net doesn't cause double switching si_double_switch-
   ing_slack will be "POSITIVE". If the victim net load pins doesn't have
   CCS-Noise model information, the attribute will be reported as "INIFIN-
   ITY".

   The victim nets having the double switching is automatically reselected
   to higher iteration so that they could be reanalyzed with more accurate
   analysis.

   The double switching happens when, the switching bump & transition time
   are large and fed into driver which strong enough amplify this. To
   avoid double switching either of them can be reduced.

Mock response to Devang

How's going with the ptsi ?

I am trying to understand several more options. I have some questions to ask Felicia/Amit and waiting for their response. I think I could have some recommendation middle this week.

NOISE

pt_shell> report_noise_parameters
****************************************

Report : noise_parameters
Design : gfx3D
Version : B-2008.12-SP2

Date : Mon Oct 25 10:19:34 2010
****************************************

analysis mode : report_at_source
analysis effort : high

ignore arrival : false
include beyond Rails : false

enable propagation : false

Helen, Jeffrey and Stephane

408-896-8810

Thursday, October 21, 2010

0ps input transient time issue

1. I guess it is because lack of input_driving_cell

2. the input cap zero issue: I guess it is because the port is floating

3. Big output transient time, there is no output load.

-Jeff