Cadence ENCOUNTER LIBRARY CHARACTERIZER Datasheet - page 3
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ENCOUNTER LIBRARY CHARACTERIZER
loading on the output. Encounter Library
Characterizer accurately generates these
models to support synthesis and static
timing analysis (STA), and provides a
baseline for more advanced modeling
formats.
ECSM DELAY MODEL
CHARACTERIZATION
Modeling the voltage impact on delay
can be particularly problematic for
low-power applications. The Effective
Current Source Model (ECSM) timing
model is an advanced cell driver model
that represents the effect of non-linear
switching waveforms on cell-based
interconnect delay calculation. It has
consistently demonstrated superior delay
calculation accuracy by modeling a cell’s
output drive as a current source rather
than a voltage source. Current sources
are more effective at tracking non-linear
transistor switching behavior and they
permit highly accurate modeling of the
complex interconnect common in today’s
largest low-power nanometer designs. It
is also the only approved standard from
the Silicon Integration Initiative’s Open
Modeling Coalition (www.si2.org).
ECSM delay model characterization:
• Used for thousands of tapeouts since
2001
• Delivers accuracy to within 2% of SPICE
with non-linear IR drop derating
– .lib (NLDM) can be off by as much as
20%
• Is an Si2-approved standard
• Offers voltage-based characterization
for greater accuracy and ease of
adoption
• Supports multi-piece pincap modeling
for greater accuracy on short, high-
fanout nets
• Works with Cadence Encounter Digital
Implementation System, Encounter
Timing System, and third-party tools
ECSM POWER MODEL
CHARACTERIZATION
Encounter Library Characterizer generates
ECSM power inside the .lib format
library and enables dynamic or static
gate-level power-consumption analysis
by characterizing the actual current
drawn from the power grid at any given
time for individual cells. The extension
allows storage of current waveforms at
power-grid pins for different combinations
of slew and load.
ECSM power model characterization:
• Generates Si2-approved ECSM power
extensions
• Characterizes dynamic current signa-
tures of power and ground pins, repre-
sented in ECSM as current waveforms
– Supports either 2D or 3D lookup
tables
– Generates piecewise linear (PWL)
representations of current waveforms
• Can incrementally add ECSM power
extensions to existing .lib
• Is supported by Encounter Power
System and Encounter Timing System
ECSM NOISE MODEL
CHARACTERIZATION
The risk of signal integrity (SI)-related
failures in silicon increases greatly at
90nm and below. Using advanced
voltage-in/voltage-out relationships,
Encounter Library Characterizer can
generate ECSM noise extensions to .lib
that enable SI analysis technologies
such as Encounter Timing System to
model the cumulative effects of noise
introduced by coupling capacitances
in complex scenarios where multi-Vt
and multi-voltage devices commingle.
The SI extensions are based on the cdB
format, which is production-proven in
more than 1,000 tapeouts. When used
in conjunction with power and timing
extensions, the noise extensions to ECSM
will accurately measure the cumulative
impact of IR drop and noise on delay and
provide a comprehensive view of timing
as well as power signoff.
ECSM noise model characterization:
• Generates Si2-approved ECSM noise
extensions
• Characterizes for noise delay and glitch
models
– Accurately models the driving stage
of each gate noise on delay
– Models the effective holding resis-
tance of the output stage of the cell
for glitch analysis
• Uses advanced voltage-in/voltage-out
(ViVo) models that capture the effective
cell I-V characteristics
– Each current model is represented
by a ViVo waveform on an input or
output pin of a cell
– 2D lookup table is used to store
values of I (Vi, Vo)
• Also considers internal pins
• Is supported by Encounter Timing
System and Encounter Digital
Implementation System
CCS TIMING MODEL
CHARACTERIZATION
The Composite Current Source (CCS)
Model is a new, current-based model
similar to ECSM that models current
vs. time and multi-piece capacitances
to enable more accurate static timing
analysis. Encounter Library Characterizer
provides efficient CCS characterization,
which picks current waveform points
intelligently to maximize accuracy while
minimizing library size.
CCS NOISE MODEL
CHARACTERIZATION
The CCS Noise model provides cell-level
noise models to enable support for some
noise analysis solutions. Characterization
includes:
• Current-based driver model
• Receiver model