Top 10 New Features in theSmartSpice 2021 Baseline Release
Introduction
Silvaco’s SmartSpice™ is a high-performance parallel
SPICE simulator which provides a proven andcomprehensive analysis solution. Applications range fromcomplex, high-precision analog and mixed-signal circuits
to flat panel displays and TFT arrays, image sensors,
memory designs, custom digital circuits, andcharacterization of standard cell libraries of advanced
semiconductor processes, among many others.
SmartSpice offers multiple simulation flavors:• SmartSpice HPP: Silvaco’s High-Performance
Parallel engine, for Fast Analog (a.k.a. QuasiSPICE) engine;• SmartSpice Pro: Silvaco’s FastSPICE engine;• SmartSpice RF: Silvaco’s bundled solution withseveral specialized engines needed for RFanalyses;• SmartSpice Server: Silvaco’s solution for
distributed simulation across nodes in a network;• Harmony: For general analog/digital cosimulation;and many more, as listed on www.silvaco.com/.
Silvaco’s SmartSpice team around the world has beenworking constantly to improve the tool’s quality andaddress customer requests. The team strives to makeSmartSpice an industry-leader SPICE simulator, and they
have been successful in achieving a significant measure
towards this goal over the last year.
In this document, we describe the top 10 new featuresand improvements enabled by the SmartSpice teamduring this last year. In this case, we are comparing the2021 Baseline Release, SmartSpice 5.0.3.R, against the2020 Baseline Release, SmartSpice 4.44.3.R.

7. Improvements on SmartSpice Server: Crossplatform simulation is now available;
8. Improved Back Annotation flow: Extended support
to improve robustness;
9. Improved Parallel .ALTER flow: Control the numberof threads of child processes; and10. New External Sampling feature: Set yourself thevalues for statistical parameters when running Monte
Carlo simulations.
Continue reading and watch the embedded videos to learn
more about each of these features.

1. Performance and Capacity Improvements
Performance (the ability to complete simulations in ashorter turnaround time without losing accuracy) andcapacity (the ability to simulate larger circuits) has always
been two of the main R&D focuses of any SPICE
simulator. This is certainly not different for the SmartSpiceproducts.
Over the last year, great improvements have been madewithin this regard, and the SmartSpice team is happy toannounce that SmartSpice 5.0.3.R (Baseline 2021) ismuch faster and memory optimized when compared to
SmartSpice 4.44.3.R (Baseline 2020) for off-the-shelf
simulations. In some cases, one can see modest 1.10x
speedup and/or 1.03x memory reduction. In other cases,
the improvements can be more significant, with around 2x
speedup and 2x memory reduction, simultaneously. In afew other cases, the gains are even higher, going around4-5x speedup and around 9-10x memory reduction,simultaneously.
The following video presents more details about theseimprovements.

The Top 10 new features and improvements are focusedon the following aspects:
1. Performance and capacity improvements: Up to
4x speedup and 9x memory reduction;
2. Support for RHELS/CentOS 8: A key enabler for
those migrating away from RHEL/CentOS 6;
3. New Graphical User Interface (GUI) technology:
Faster and more stable experience;
4. Improvements on SmartSpice RF: Completely
revised periodic steady-state and phase noise flows;
5. Improvements on SmartSpice Pro: A variety ofenhancements for a better user experience;
6. Improved Spectre® compatibility mode: Keyenablers for simulations using the Spectre language;

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2. Support for RHEL/Centos 8
In terms of Operating System (OS) and Platform
support, the Silvaco tools released with Baseline 2020,
last Summer, supported 64-bit platforms based on thefollowing operating systems:• Red Hat Enterprise Linux (RHEL) 6 and 7;• CentOS Linux 6 and 7; and• Windows Professional 7, 8, 8.1 and 10.
Focusing on the UNIX-based OS, Maintenance Supportfor RHEL/CentOS 6 ended on November 30, 2020. With
that, many users are considering migrating to RHEL 8,or other EL-based OS. In order to enable them for sucha migration, the SmartSpice team is happy to announce
that the SmartSpice products now support
RHEL/CentOS 8 as well. This includes all SmartSpiceproducts, including Harmony.
An important comment, though, is that the CentOS Linux
distributions have been historically released as rebuilds
of RHEL distributions. However, this is changing thisyear. CentOS Linux 8, as a rebuild of RHEL 8, will end
on Q4 2021. CentOS Stream continues after that date,serving as the upstream (development) branch of RHEL.
There is still some uncertainty about which new Linux
distribution will take place as a rebuild of RHEL.
Nonetheless, one should rest assured that, whenevermore clarity is brought to this context, the SmartSpiceand the Silvaco teams will work diligently to stay up todate with it.

3. New GUI Technology
Another major change in SmartSpice for this 2021
Baseline release is the technology underlying its
graphical user interface (GUI). Yet, it is worth mentioningthat very minimal differences are noticeable from a user
experience perspective right now. The main focus of thisenhancement is on the graphic engine itself. This is thefirst of a crucial two-step process towards an improved
interface, planned to be finished by Baseline 2022.
The new GUI, which has just been released, not only
brings to SmartSpice the state of the art in terms ofgraphics and window rendering, but it is also an enabler.
Its new technology improves performance androbustness, also allowing for new degrees of testability
and maintainability. This all reflects on a faster and morestable experience.
As it is based on a brand-new engine, some of the GUI
preferences are not automatically inherited fromprevious versions. In this case, the users are strongly
recommended to run SmartSpice with the “-qt3” flag(which will bring the old engine up), export thepreferences, run SmartSpice again (now with the newGUI), and import the preferences back in. The following
video quickly introduces the new GUI and demonstrates
this export/import process.

4. Improvements on SmartSpice RF
The 2021 Baseline release also brings a collection ofexciting enhancements for SmartSpice RF. Most of these
improvements are related to a completely revisited
Shooting-Newton-based phase noise analysis flow. Majorchanges were made:1.

A much improved .pss analysis, with a morerobust periodic steady-state algorithm including
better support for oscillator circuits; as well as

2.

A brand new Perturbation Projection Vector(PPV) algorithm for more accurate oscillator
phase noise analysis.

The following video introduces these improvements anddemonstrates its benefits on a circuit.

The simulation setup demonstrated in this video isshipped along with the 2021 Baseline release. Please,feel free to try it yourself.
Much more is still to come. For the 2022 Baseline, theSmartSpice team plans to release an enhanced
pnoise/hnoise analysis, now with a Frequency-Aware
PPV capability. This will allow SmartSpice RF to capture
long time-constant effects. The team is also planning tostart revisiting our Harmonic Balance flow. So, please,stay tuned!

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5. Improvements on SmartSpice Pro
With the ever-growing complexity of circuit designs, thechallenges of verification are intensified. In some of thecases, regular SPICE simulation cannot deliver thedesired set of results in due time, and FastSPICE
engines become necessary. This is when SmartSpicePro comes into play.
Over the last year, SmartSpice Pro has also received
good attention from our R&D team. With this, a varietyof improvements are being made available on its 2021
Baseline release, such as:• Improved flows for bisection optimizations andMonte Carlo analyses;• Improved partitioning algorithms;• Improved support for PWL voltage and current
sources;along with many other fixes.

6x speedup, reducing a 22-hour simulation down to 3.5
hours, just for using this feature.
Up to the 2020 Baseline release, last year, SmartSpice
Server was basically working only if servers and agentswere based on the same operating system. Now, on the2021 Baseline release, SmartSpice Server is able tolaunch jobs in a cross-platform environment, i.e., users
can not only dispatch simulations from Linux to Linux orfrom Windows to Windows (as they could already dobefore), but they can now also run SmartSpice Serverfrom Linux to Windows or from Windows to Linux as well.
More details about it are presented in the following video:

We strongly encourage you to download the tool andcheck it out by yourself.

6. Improved Spectre Compatibility Mode
SmartSpice is not only a proven, mature SPICE
simulator. It is also one of the most flexible simulators in
the market. We count first on our 30+ years of feature,model and analysis development, which bring to ourusers a variety of unique features. On top of that, wehave a strong HSPICE® compatibility mode, along withan ever-growing Spectre® compatibility mode.
In the 2021 Baseline release, SmartSpice pushed its
Spectre support even further, with many improvementsthat are key enablers for the simulation of circuits using
Spectre language, or even SPICE-described circuits
relying on Spectre models. A few of these improvements
are listed below:•Improved support for the TSMC Model
Interface (TMI) under Spectre mode;•Improved handling of user-defined functions
and parameters in Spectre mode;•Added support for new models; and•
Improved support for general Spectre syntax;

8. Improved Back Annotation FlowAs technology advances, the need for post-layout
simulation becomes more and more real. The effects fromparasitic devices are continuously more important, andpre-layout simulation (with an ideal, no-parasitic netlist)
tends not to reflect real silicon behavior. With this, running
SPICE simulation including layout parasitics is becoming
a rule.
Traditionally, the way to handle post-layout simulation isby including the parasitic netlist as a replacement of thepre-layout block. However, as parasitic netlists areusually flat, the advantages of hierarchical-based
designing are lost.

among many others.
It would be a pleasure to have you trying SmartSpice’sSpectre compatibility mode.

7. Improvements on SmartSpice Server
SmartSpice Server brings the capability of running
distributed jobs. With this, SmartSpice users are able toexecute a server process on a given node on a networkand dispatch simulation jobs to multiple other computer
nodes in their network or computer farm. Additionally, its
unique split and slice functionalities make it possible totake a single, time-consuming job and speed up its
simulation time by dividing the simulation in smallerparts and distributing these tasks across nodes in anetwork. A given customer already reported more thanSince the 2020 Baseline release, last year, SmartSpicehas been supporting another, more optimized flow for thisproblem, called Post-Layout Back Annotation. With this,SmartSpice is able to read both netlists, take parasitic
devices from the DSPF netlist, and annotate them backonto the ideal netlist. This brings to circuit designers theability to play with the advantages of hierarchical designs
and post-layout simulations, simultaneously.
Another major improvement on the 2021 Baseline releaseis an enhanced Back Annotation flow. A few of theenhancements are listed below:• Added support for macro models on parasitic
netlists; and• Added support for multiply factors on ideal netlists,
among others.
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It is worth mentioning that these enhancements are also
supported by the Selective-Net Back Annotation flow.
Please, try the Back Annotation flow included in the2021 Baseline release. Any related feedback would be
most welcome!

9. Improved Parallel .ALTER Flow
The SmartSpice Parallel .ALTER flow is a well-known
functionality, much used by customers. In a nutshell, if(a) the input deck contains multiple .ALTER statements,and (b) SmartSpice MultiCore is used, then SmartSpiceby default creates a pool of child processes based bothon the number of .ALTER statements and the adopted
number of cores in the simulation. Then, it will run each.ALTER simulation in parallel, as if they wereindependent circuits. This is a very interesting feature tospeed up the simulation time by taking advantage of themodern multicore hardware platforms.

As this is only its first release, more is still to come. The
upcoming Quarterly Releases should extend thefunctionality, e.g. adding support for TMI models. If this
topic is of any interest, please, stay tuned!

Until now, each of these child processes was running ina single thread, and the users did not have a way tocontrol the number of threads per child process.
This has changed in the 2021 Baseline release. From
this version on, one can now use an extra command-line
argument “-PA <numthreads>” and set the number ofthreads for child process in the parallel .ALTER mode.
It is strongly recommended to download the tool andcheck it out on your own.

10. New External Sampling Feature forMonte Carlo Analyses
When running a Monte Carlo analysis, the default
behavior of a SPICE simulator is to adopt one of its builtin sampling algorithms and, for each Monte Carloiteration, set random values for each of the statisticalparameters in the circuit, according to their associateddistribution. Although it is not generally a problem, thismethodology makes it difficult for design and process
exploration when it comes to statistical experiments.
In the 2021 Baseline, SmartSpice presents its firstrelease of External Sampling. This new functionality
allows our users to set the values for statisticalparameters themselves when running Monte Carlosimulations. The following video demonstrates theprocess in more details.

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