Introduction

Multiphysics is an integral part of the concepts around digital twins. In this post, I want to discuss the mechanical aspects of multiphysics in system simulations, which are critical for 3D-IC, multi-die, and chiplet design.

The physical world in which we live is growing ever more electrified. Think of the transformation that the cell phone has brought into our lives, as has the present-day migration to electronic vehicles (EVs). These products are not only feats of electronic engineering but of mechanical as well, as the electronics find themselves in new and novel forms such as foldable phones and flying cars (eVOTLs). Here, engineering domains must co-exist and collaborate to bring about the best end products possible.

Start with the electronics—chips, chiplets, IC packaging, PCB, and modules. But now put these into a new form factor that can be dropped or submerged in water or accelerated along a highway. What about drop testing, aerodynamics, and aeroacoustics? These largely computational fluid dynamics (CFD) and/or mechanical multiphysics phenomena must also be accounted for. And then how does the drop testing impact the electrical performance? The world of electronics and its vast array of end products is pushing us beyond pure electrical engineering to be more broadly minded and develop not only heterogeneous products but heterogeneous engineering teams as well.

Cadence's Unique Expertise

It's at this crossroad of complexity and electronic proliferation that Cadence shines. Let's take, for example, the latest push for higher-performing high-bandwidth memory (HBM) devices and AI data center expansion. These technologies are growing from several layers to 12, and I can't emphasize enough the importance of teamwork and integrated solutions in tackling the challenges of advanced packaging technologies and how collaboration is shaping the future of semiconductor innovation and paving the way for cutting-edge developments in the industry.

These layered electronics are powered, and power creates heat. Heat needs to be understood, and thus, the thermal integrity issues uncovered along the way must be addressed. However, electronic thermal issues are just the first domino in a chain of interdependencies. What about the thermal stress and warpage that can be caused by the powering of these stacked devices? How does that then lend to mechanical stress and even material fatigue as the temperature cycles from high to low and back through the use of the electronic device? This is just one example in a long list of many...

Cadence Multiphysics Analysis Offerings

The confluence of electrical, mechanical, and CFD is exactly why Cadence expanded into multiphysics at a significant rate starting in 2019 with the announcement of the Clarity 3D Solver and Celsius Thermal Solver products for electromagnetic (EM) and thermal multiphysics system simulations. Recent acquisitions of Numeca, Pointwise, and Cascade (now branded within Cadence as the Fidelity CFD Platform) as well as Future Facilities (now the Cadence Reality Digital Twin product line) are all adding CFD expertise. The recent addition of Beta CAE brings mechanical multiphysics to the suite of solutions available from Cadence. The full breadth of these multiphysics system analyses, spanning EM, thermal, signal integrity/power integrity (SI/PI), CFD, and now mechanical, creates a platform for digital twinning across a wide array of applications. You can learn more by viewing Cadence's Reality Digital Twin platform launch on the keynote stage at NVIDIA's GTC in March, as well as this Designed with Cadence video: NV5, NVIDIA, and Cadence Collaboration Optimizes Data Centers.

Conclusion

Ever more sophisticated electronic designs are in demand to fulfill the needs of tomorrow's technologies, driving a convergence of electrical and mechanical aspects of multiphysics in system simulations. To successfully produce the exciting new products of the future, both domains must be able to collaborate effectively and efficiently. Cadence is fully committed to developing and providing our customers with the software products they need to enable this electrical/mechanical evolution. From EM, to thermal, to SI/PI, CFD, and mechanical, Cadence is enabling digital twinning across a wide array of applications that are forging pathways to the future.

For more information on Cadence's multiphysics system analysis offerings, visit our webpage and download our brochure.

Does anyone know whether it is possible to have multiple contact points for a bond wire on a large die pad? Note: This is different from adding multiple wires which I will also be doing. I need to add multiple bond connections to the same large die pad for redundancy connections to each pad for each wire. I have a large die pad which I need to have 5 wires with each wire having 3 bond connections to the same die pad.

Have you ever thought of a handy utility to specify all necessary transmission line parameters to decide upon the stackup?   

Starting SPB 23.1, a handy feature Transmission Line Calculator, is built into Allegro X Advanced Package Designer (Allegro X APD). This feature will require either an SiP Layout license or can be accessed through SiP Layout Bundle. 

From the Analyze dropdown menu in the 23.1 Allegro X APD toolbar, you can choose Transmission Line Calculator. 

You can use this calculator to help decide constraints and stackup for laminate-based PCB or Packages. You can calculate the correct stackup material and width/spacing to meet any requirements that may be later entered in a constraint. This is truly a calculated number and not a true field solver. 

The different types of calculations that the Transmission Line Calculator can provide are Microstrip, Embedded microstrip, Stripline, CPW (Coplanar), FGCPW (frequency-dependent Coplanar), Asymmetric stripline, Coupled microstrip (Differential Pair), Coupled stripline (Differential Pair), and Dual striplines. 

This feature is important for customers relying on fabricators/spreadsheets to provide this information or need to test a quick spacing/width as per the impedance value. 

Let us know your comments on this new feature in 23.1 Allegro X APD. 

In a package design, designers often need to perform degassing. This is typically done at the end of the design process before sending the design to the manufacturer.

Degassing is a process where you perforate power planes, voltage planes, and filled shapes in your design. Degassing holes let the gas escape from beneath the metal during manufacturing of the substrate. The perforations or holes for degassing are generally small, having a specified size and shape, and are spaced regularly across the surface of the plane. If the degassing process is not done, it may result in the formation of gas bubbles under the metal, which may cause the surface of the metal to become uneven. After you degas the design, it is recommended to perform electrical verification.

Allegro X APD has degassing features that allow users to automate the process and place holes in the entire shape.

In today’s topic, we will talk about how to avoid adding  degassing holes on a particular shape.

Sometimes, a designer may need to avoid adding degassing holes to a particular shape on a layer. All other shapes on the layer can have degassing holes but not this shape. Using the Layer Based Degassing Parameters option, the designer can set the degassing parameters for all shapes on the layer. Now, the designer would like to defer adding degassing holes for this particular shape.

You may wonder if there is an easy way to achieve this. We will now see how this can be done with the tool.

Once the degassing parameters are set, performing Display > Element on any of the shapes on that layer will show the degassing parameters set.

You can apply the Degas_Not_Allowed property to a shape to specify that degassing should not be performed on this shape, even if the degassing requirements are met. Select the shape and add the property as shown below.

Switch to Shape Edit application mode (Setup > Application mode > Shape Edit) and window-select all shapes on the layer. Then, right-click and select Deferred Degassing > All Off.

Now, all shapes on the layer will have degassing holes except for the shape which has the Degas_Not_Allowed property attached to it.

By default, a dielectric must separate each pair of conductor layers in the cross-section of a design. In rare cases, this does not represent the real, manufactured substrate.

If your design requires you to have conductor layers that are not separated by a dielectric (such as, for half-etch designs), there is a variable that needs to be set in Allegro X APD. You must set this by enabling the variable icp_allow_adjacent_conductors. This entry, and its location in the User Preferences Editor, are shown in the following image.

The Objects on adjacent conductor layers do not electrically connect together, automatically. A via must be used to establish the inter-layer connections.

When enabling this option, it is recommended to exercise caution because excluding dielectric layers from your cross-section can lead to inaccurate calculations, including the calculations for signal integrity and via heights. It is important that your cross-section accurately reflect the finished product to ensure the most accurate results possible. Any dielectric layers present in the manufactured part need to be in the cross-section for accurate extraction, 3D viewing, and so on.

Let us know your comments on the various designs that would require adjacent conductor layers.

The Cadence Palladium Emulation Platform is a hardware system that implements the design, accelerating its execution and verification. Itoffers the highest performance and fastest bring-up times for pre-silicon validation of billion-gate designs, using a custom processor built by Cadence.

This Palladium Introduction course is based on the Palladium 23.03 ISR4 version and covers the following modules:

• Introduction
• Palladium flow
• Running a design on the Palladium system

This course starts with an “Introduction” module that explains Palladium and other verification platforms to show its place in the big picture. It also compares Palladium with Protium and simulation and discusses its usage and limitations.

The “Palladium Flow” module includes two stages at a high level, which are Compile and Run. Then, it covers these stages in detail. First, it covers the ICE compile flow and IXCOM compile flow steps in detail. Then it explains Run, which is common for both ICE and IXCOM modes.

The third module, “Running Design on the Palladium System,” covers all the items required for running your design on the Palladium system, including:

• Software stack requirements
• Basic concepts required to understand the flow
• Compute machine requirements

In addition, this course contains labs for both the ICE and IXCOM flows with detailed steps to exercise the features provided by the Palladium system. The lab explains a practical example of multiple counters and exercising their signals for force, monitor, and deposit features, along with frequency calculation using a real-time clock. The course is available on the Cadence support page:

There is also a Digital Badge available. You will find the Badge exam opportunity when you enroll in the Online training or after you have taken the training as "live" training.

For questions and inquiries, or issues with registration, reach out to us at Cadence Training. Want to stay up to date on webinars and courses? Subscribe to Cadence Training emails. To view our complete training offerings, visit the Cadence Training website.

Related Training Bytes

• Palladium: What Are Verification Platforms
• Palladium: What Is Processor Based Emulation
• Palladium: Comparing Emulation (Z2) and Prototyping (X2)
• Palladium: What Are ICE and IXCOM Compile Flow
• Palladium: How to Process a Design to Run on Palladium
• Palladium: XCOM Compile Flow (TB+RTL to Palladium Database)
• Palladium: ICE Compile Flow (RTL to Palladium Database)
• Palladium: Legacy ICE Compile Flow
• Palladium: Cadence Software Releases for Palladium and Protium Flow
• Palladium: Setting of PATHs for Using Palladium
• Palladium: Z2 Hardware Structure (Blade and Boards)
• Palladium: What Is Sourceless and Loadless nets
• Palladium: Design Clocks
• Palladium: Step Count and Step Clock
• Palladium: Steps for Running the Design on Palladium Z2

Related Courses

• Verilog Language and Application Training
• SystemVerilog for Design and Verification
• Xcelium Simulator

Related Blogs

• Training Insights – A New Free Online Course on the Protium System for Beginner and Advanced Users
• It’s the Digital Era; Why Not Showcase Your Brand Through a Digital Badge!
• Training Insights - Free Online Courses on Cadence Learning and Support Portal

An increasing number of embedded designs are multi-core systems. At the pre-silicon stage, customers use a simulation platform for architectural exploration and software development. Architects want to quantify the impact of the number of cores, local memory size, system memory latency, and interconnect bandwidth. Software teams wish to have a practical development platform that is not excruciatingly slow. This blog shares a recipe for simulating Cadence DSPs in a multi-core design as separate x86 processes. The purpose is to reduce simulation time for customers with simple multi-core models where cores interact only through shared memory. It uses a Vision Q8 multi-core design to share details of the XTSC (Xtensa SystemC) model, software application, commands, and debugging. Note the details shared are for a simulation run on an Ubuntu Linux machine, Xtensa tools version RI-2023.11, and core configuration XRC_Vision_Q8_AODP. Complex vs. Simple Model A complex model (Figure 1) is one in which one core accesses another core's local memory, or there are inter-core interrupts. Simulation runs as a single x86 process. Figure 1 A simple model (Figure 2) is one in which cores interact only through shared memory. Shared memory is a file on the Linux host. Figure 2 Multiple x86 Process – Simple Model As depicted in Figure 3, each core is simulated using a separate x86 process. Cores use barriers and locks placed in shared memory for synchronization and data sharing. Locks are placed in un-cached memory that support exclusive subordinate access. The XTSC memory component, xtsc_memory , supports exclusive subordinate access. Cadence software tools provide a way to define memory regions as cached or uncached. For more details, please refer to Cadence's Linker Support Packages (LSP) Reference Manual for Xtensa SDK . Figure 3 Demo Application A demo application performs a 128x128 matrix multiplication. Work is divided so that each of the 32 cores computes four rows of the 128x128 result matrix. Cores use barriers to synchronize. Cadence tools provide APIs for synchronization and locking. Please refer to Cadence's System Software Reference Manual for more details. Note without a higher-level lock, prints from all cores will get mixed up. Therefore, in the demo application, only core#0 prints. SystemC Simulation The following sample command runs the 32-core simulation in such a way that each core is a separate x86 process. It runs a matrix multiplication application in cycle-accurate mode with logging off. >>for (( N=0; N >xtsc-run -define=NumCores=32 -define=N=0 -define=LOGGING=0 -define=TURBO=0 --xxdebug=sync -i=coreNN.inc -sc_main=sc_main.cpp -no_sim Modify the sc_main.cpp generated for core#0 to create a generic sc_main.cpp to build a single simulation executable for all cores. The Xtensa SDK includes Makefile targets to build custom simulations. By default, the simulation runs in cycle-accurate mode. Fast functional (Turbo) mode provides additional improvement over cycle-accurate mode. Note that the fast functional mode has an initialization phase, so gains are visible only when running an application with longer run times. Simulation Wall Time The table captures simulation wall time improvements. Note that these are illustrative wall time numbers. Actual wall time numbers and improvements will depend on your host machine's performance and your application. Simulation Type Wall Time Comments Single process cycle accurate mode 17500 seconds Multiple x86 processes cycle accurate mode 1385 seconds 12X faster than single process Multiple x86 processes turbo mode 415 seconds 3X faster than cycle accurate mode Debugging Attaching a debugger to each of the individual x86 core simulation processes is possible. Synchronous stop/resume and core-specific breakpoints are also supported. Configure the Xplorer launch configuration and attach it to the running simulation processes as follows (Figure 5) Figure 5 Figure 6 shows 32 debug contexts. Figure 6 As shown, using Xtensa SDK, you can create a multi-core simulation that functions as a practical software development platform. Please visit the Cadence support site for information on building and simulating multi-core Xtensa systems.

hi,

     I save the waveform file of the oscilloscope as CSV file format.

     Now, I need to use this waveform file as the source of the low-pass filter .

     I searched and read the PSPICE help documents, and did not find any  methods. 

     How to realize it?

     Are there any reference documents or examples?

     Thanks!

Please give me some ideas. Thank you very much.

This is the 21st installment of The Rationalist, my column for the Times of India.

When all political parties agree on something, you know you might have a problem. Giriraj Singh, a minister in Narendra Modi’s new cabinet, tweeted this week that our population control law should become a “movement.” This is something that would find bipartisan support – we are taught from school onwards that India’s population is a big problem, and we need to control it.

This is wrong. Contrary to popular belief, our population is not a problem. It is our greatest strength.

The notion that we should worry about a growing population is an intuitive one. The world has limited resources. People keep increasing. Something’s gotta give.

Robert Malthus made just this point in his 1798 book, An Essay on the Principle of Population. He was worried that our population would grow exponentially while resources would grow arithmetically. As more people entered the workforce, wages would fall and goods would become scarce. Calamity was inevitable.

Malthus’s rationale was so influential that this mode of thinking was soon called ‘Malthusian.’ (It is a pejorative today.) A 20th-century follower of his, Harrison Brown, came up with one of my favourite images on this subject, arguing that a growing population would lead to the earth being “covered completely and to a considerable depth with a writhing mass of human beings, much as a dead cow is covered with a pulsating mass of maggots.”

Another Malthusian, Paul Ehrlich, published a book called The Population Bomb in 1968, which began with the stirring lines, “The battle to feed all of humanity is over. In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now.” Ehrlich was, as you’d guess, a big supporter of India’s coercive family planning programs. ““I don’t see,” he wrote, “how India could possibly feed two hundred million more people by 1980.”

None of these fears have come true. A 2007 study by Nicholas Eberstadt called ‘Too Many People?’ found no correlation between population density and poverty. The greater the density of people, the more you’d expect them to fight for resources – and yet, Monaco, which has 40 times the population density of Bangladesh, is doing well for itself. So is Bahrain, which has three times the population density of India.

Not only does population not cause poverty, it makes us more prosperous. The economist Julian Simon pointed out in a 1981 book that through history, whenever there has been a spurt in population, it has coincided with a spurt in productivity. Such as, for example, between Malthus’s time and now. There were around a billion people on earth in 1798, and there are around 7.7 billion today. As you read these words, consider that you are better off than the richest person on the planet then.

Why is this? The answer lies in the title of Simon’s book: The Ultimate Resource. When we speak of resources, we forget that human beings are the finest resource of all. There is no limit to our ingenuity. And we interact with each other in positive-sum ways – every voluntary interactions leaves both people better off, and the amount of value in the world goes up. This is why we want to be part of economic networks that are as large, and as dense, as possible. This is why most people migrate to cities rather than away from them – and why cities are so much richer than towns or villages.

If Malthusians were right, essential commodities like wheat, maize and rice would become relatively scarcer over time, and thus more expensive – but they have actually become much cheaper in real terms. This is thanks to the productivity and creativity of humans, who, in Eberstadt’s words, are “in practice always renewable and in theory entirely inexhaustible.”

The error made by Malthus, Brown and Ehrlich is the same error that our politicians make today, and not just in the context of population: zero-sum thinking. If our population grows and resources stays the same, of course there will be scarcity. But this is never the case. All we need to do to learn this lesson is look at our cities!

This mistaken thinking has had savage humanitarian consequences in India. Think of the unborn millions over the decades because of our brutal family planning policies. How many Tendulkars, Rahmans and Satyajit Rays have we lost? Think of the immoral coercion still carried out on poor people across the country. And finally, think of the condescension of our politicians, asserting that people are India’s problem – but always other people, never themselves.

This arrogance is India’s greatest problem, not our people.

The India Uncut Blog © 2010 Amit Varma. All rights reserved.
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During a mixed-signal simulation, the analog engine usually dominates the simulation time and resources. If you need to run only the analog engine in several windows, or if you would like to to run multiple tests of the same circuit with different stimuli or test pattern, then you need to run the simulation multiple times. View this blog to know more about the the two advanced technologies that Spectre AMS Designer provides to help you improve the efficiency of your mixed-signal designs and to increase the simulation speed.(read more)

This blog describes an efficient way to name the histories saved by the simulation runs in Virtuoso ADE Assembler.(read more)

Read this blog to know how you can easily create and insert connect modules using Spectre AMS Designer with the Verilog-AMS standard language defined by Accellera. (read more)

Have you ever wanted to write a DRC rule deck to check for space or width constraints on polygons? Or have you wondered how the multiple lines of an LVS rule deck extract and conduct a comparison between the schematic and layout? Maybe you've been curious about the role of rule deck writers in creating high-quality designs ready for tape-out.

If any of these questions interest you, there is good news: the latest version (v23.1) of the Physical Verification Rules Writer (PVLRW) course is designed to teach you rule deck writing. This free 16-hour online course includes audio and labs designed to make your learning experience comfortable and flexible. Whether you are new to the concept or an experienced CAD/PDK engineer, the course is structured to enhance your rule deck writing skills.

The PVLRW course covers six core modules: Layer Processing, DRC Rules, Layout Extraction, ERC and LVS Rules, Schematic Netlisting, and Coloring Rules. There are also three optional appendix sections. Each module explains relevant rules with syntax, concepts, graphics, examples, and case studies.

This course is based on tool versions PEGASUS231 and Virtuoso Studio IC231.

Pegasus Input and Output

Pegasus is a cloud-ready physical verification signoff solution that enables engineers to support faster delivery of advanced-node integrated circuits (ICs) to market.

Pegasus requires input data in the form of layout geometry, schematic netlists, and rules that direct the tool operation. The rules fall into two categories: those that describe the fabrication process and those that control the job-specific operation.

Pegasus provides log and report files, netlists, databases, and error databases as output.

Overview of Pegasus Rule File

The rule decks written in Physical Verification Language (PVL) work for the Cadence PV signoff tools Pegasus and PVS (Physical Verification System).   

The PVL rules are placed in a file that gets selected in a run from the GUI or the command line, as the user directs. PVL rules may be on separate lines within the file and can also be contained in named rule blocks.

Each line of code starts with a PVL rule that uses prefix type notation. It consists of a keyword followed by options, input layer or variable names, and output layer or variable names.

A rule block has the format of the keyword rule, followed by a rule name you wish to give it, followed by an opening curly brace. You enter the rules you wish to perform, followed by a closing curly brace on the last separate line.

  Sample Rule deck with individual lines of code and rule blocks.

DRC Rules

The first step in a typical Pegasus flow is a Design Rule Check (DRC), which verifies that layout geometries conform to the minimum width, spacing, and other fabrication process rules required by an IC foundry. Each foundry specifies its own process-dependent rules that must be met by the layout design.

There are three types of DRC rules: layer definition rules, layer derivation rules, and DRC design check rules. Layer definition rules identify the layers contained in the input layout database, and layer derivation rules derive additional layers from the original input layers, allowing the tool to test the design against specific foundry requirements using the design check rules.

A sample DRC Rule deck

A layout view displaying the DRC violations

LVS Rules

The Pegasus Layout Versus Schematic (LVS) tool compares the layout netlist with the schematic netlist to check for discrepancies.

There are two essential LVS rule sets: LVS extraction rules and comparison rules. LVS extraction rules help extract drawn devices and connectivity information from the input layout geometry data and outputs into a layout netlist. The LVS extraction rule set also includes the layer definition, derivation, extraction, connectivity, and net listing rules.

LVS comparison rules are associated with comparing the extracted layout netlist to a schematic netlist.

A sample LVS Rule deck. 

TCL, Macros, and Conditional commands

Tcl is supported and used in various Pegasus functionalities, such as Pegasus rule files and Pegasus configurator. Macros are functional templates that are defined once and can be used multiple times in a rule file. Conditional Commands are used to process or skip specific commands in the rule file.

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If not, follow the steps below to create your account.

• On the Cadence Support portal, select Register Now and provide the requested information on the Registration page.
• You will need an email address and host ID to sign up.
• If you need help with registration, contact support@cadence.com.

To stay up to date with the latest news and information about Cadence training and webinars, subscribe to the Cadence Training emails.

If you have questions about courses, schedules, online, public, or live onsite training, reach out to us at Cadence Training.

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Related Resources

About Knowledge Booster Training Bytes

Knowledge Booster Training Bytes is an online journal that relays information about Cadence Training videos, online courses, and upcoming webinars in the Learning section of the Cadence Learning and Support portal. This blog category brings you direct links to these videos, courses, and other related material on a regular basis. Subscribe to receive email notifications about our latest Custom IC Design blog posts.

Read this blog to know more about the innovation behind Universal Connect Modules (UCM).(read more)

The default position of the pin number is incorrect.

Dear all,

I defined two design variables in ADE Assembler, say V1 and V2, that define the voltage 1 and voltage 2 of a "vpulse" voltage source in my schematic.

Then, I define V1 = 1.0, and V2 = 2.0, run a transient simulation, and everything is as expexcted. The source provides pulses between 1.0 V and 2.0 V.

Next, I set V1 = 1.0:0.5:1.5, thereby creating a parametric sweep with 1.0 V and 1.5 V for V1. I keep V2 at 2.0 V. Then the simulation fails, and all I get is "netl err" in my Output Expressions and an error message that the results directory does not exist and nothing can be plotted: This is reasonable, as the results directory is deleted on starting a new simulation, and as there is no simulation result, none of my output expressions can be plotted.

WARNING (OCN-6040): The specified directory does not exist, or the directory does not contain valid PSF results.
        Ensure that the path to the directory is correct and the directory has a logFile and PSF result files.
WARNING (ADE-1065): No simulation results are available.
ERROR (WIA-1175): Cannot plot waveform signals because no waveform data is available for plotting.
One of the possible reasons can be that 'Save' check box for these signals are not selected in the Outputs Setup pane. Ensure that these check boxes are selected before you run the simulation.

Normally, this kind of para,metric sweep is not a problem, I have done this many times before. There must be something special in THIS PARTICULAR test bench or simulator setup. The trouble is, I don't get any useful error messages.

Does anyone know what might be the problem here OR where to find useful information to investigate further (log files stored somewhere)? Thank you!

Regards,

Volker

P.S. Using Corners instead does not help either. Running it through all values by hand works, though.

Hi, 

When I try to run Monte Carlo it gives me a 3 items message for possible failure:

1. It says the machine selected in the current job setup policy isnot reachable

2. The Cadence hierarchy is not detected, not installed properly. or

3. Job start script (with a path and a name like swiftNetlistService#) is not found on the remote machines.

Any recommendation on how to fix this?

Hello Everybody

Recently, I want to design a high output Power Amplifier at 2.4GHz using TSMC 1P6M CMOS Bulk Process. I use its nmos_rf_25_6t transistor model to determine the approximate mosfet size

I use the most common Common-Source Differential Amplifier topology with neutralizing capacitor to improve its stability and power gain performance

Because I want to output large power, the size of mosfet is very large, the gate width is about 2mm, when I perform harmonic balance analysis, everything is alright, the OP1dB is about 28dBm (0.63Watt)

But When I perform Transient simulation, the magnitude of voltage and current waveform at the saturation point is too small, for voltgae, Vpeaking is about 50mV, for current, Ipeaking is about 5mA

I assume some reasons: the bsim4 model is not complete/ the virtuoso version is wrong (My virtuoso version is IC6.1.7-64b.500.21)/the spectre version is wrong (spectre version is 15.1.0 32bit)/the MMSIM version is wrong/Transient Simulation setting is wrong (the algorithm is select gear2only, but when I select other, like: trap, the results have no difference), the maxstep I set 5ps, minstep I set 2ps to improve simulation speed, I think this step is much smaller than the fundamental period (1/2.4e9≈416ps)

I have no idea how to solve this problem, please help me! Thank you very very much!

Hello,
I'm trying to characterize a full adder that use transmission gate.
Unfortunately, the power calculation are wrong for the cell are always negative.
Is there any method or commands that can can help in power calculation or add the power consumption by the input pins to the power calculation ?
Another question, Is liberate support the characterization or transmission gate cells as standard cells or I should use liberate AMS for these type of cells ?
Thanks in advance,
Tareq 

Hello everyone,

I hope you're all doing well. I’ve set up two testbenches (TB1 and TB2) for my Design Under Test (DUT) using Cadence IC6.1.8-64b.500.21 tools, as shown in the attached figure. The DUT has multiple views available: schematic, Calibre, Maestro, and Symbol, and each testbench uses the same DUT in different scenarios. Currently, I have to manually switch between these views, but I would like to streamline this process.

My goal is to use a single config view that allows me to switch between the schematic and the extracted (Calibre) views. Ideally, I would like to have a configuration file where making changes once would update both testbenches (TB1 and TB2) automatically. In other words, when I modify one config, both testbenches should reflect this update for a single simulation run.

I would really appreciate it if you could guide me on the following:

1. How to create a config view for my DUT that can be used to easily switch between the schematic and extracted views, impacting both TB1 and TB2.
2. Where to specify view priorities or other settings to control which view is used during simulation.
3. Best practices for using a config file in this scenario, so that it ensures consistency across multiple testbenches.

Please refer to the attached figure to get a better understanding of the setup I’m using, where both TB1 and TB2 include the same DUT with multiple available views.

Thank you so much for your time and assistance!

I want to use jaspergold to formally verify functionality of my custom multiplier. I am computing the expected result using A*B to check against output of my multiplier. Here, A and B are two logic signed operands. However, jaspergold is performing the operation A*B incorrectly.

I have reproduced this issue using the attached example. JasperGold compiles and elaborates the module and subsequently runs a formal proof. The tool raises a counterexample to assertion whose screenshot is attached below:

I simulated the same example using xrun and it was giving the correct product output in simvision waveform. Please help me resolve this issue. I am using 2023.03 version of Jasper Apps.

Thanks and regards

Anubhav Agarwal

I'm completely new to Cadence. I've been able to run a very simple simulation with the -gui option. Simvision opens, I add the variables to the waveform viewer, and press run. All is good.

I don't understand the flow when using the -nogui option. It appears that the simulation runs and returns control to the OS. When I launch Simvision, is there a database or file that I can open to display the already-simulated data?

My command is of the form:

xrun -gui -64bit -sv -access +rwc -top tb_top.sv <src files>

When analyzing multiple sessions simultaneously Verisium Manager crashed and reported below error messages:

# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007efc52861b74, pid=14182, tid=18380
#
# JRE version: OpenJDK Runtime Environment Temurin-17.0.3+7 (17.0.3+7) (build 17.0.3+7)
# Java VM: OpenJDK 64-Bit Server VM Temurin-17.0.3+7 (17.0.3+7, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# C  [libucis.so+0x238b74]

......

For more details please refer to the attached log file "hs_err_pid21143.log".

Two approaches were tried to solve this problem but neither has worked.
Method.1:

Setting larger heap size of Java process by "-memlimit" options.For example "vmanager -memlimit 8G".

Method.2:

Enlarging stack memory size limit of the Coverage engine by setting "IMC_NATIVE_STACKSIZE" environment variable to a larger value. For example "setenv IMC_NATIVE_STACKSIZE 1024000"

According to "hs_err_pid*.log" it is almost certain that the memory overflow triggered Java's CrashOnOutOfMemoryError and caused Verisium Manager to crash. There are some arguments about memory management of Java like "Xms, Xmx, ThreadStackSize, Xss5048k etc" and maybe this problem can be fixed by setting these arguments during analysis. However, how exactly does Verisium Manager specify these arguments during analysis? I tried to set them by the form of setting environment variables before analysis but it didn't work in analysis and their values didn't change.

Is there something wrong with my operation or is there a better solution?

Thank you very much.

I want to do a 2-step build->simulate as follow:

1. Make multiple builds using xrun -elaborate [other options]. The purpose is to create multiple builds with different compile-time macros (+define+MACROA +define+MACROB=ABC). Each build is located in a different directory.

2. Run simulation with xrun -r. This is where I need help. How do I specify which build to simulate? Also, I need the simulation directory (with log files, …) to be different than the build directory.

Has anyone been able to achieve this or similar solutions?

Hi, I'm using the xcelium simulator to simulate a testbench, in which I first stimulate my design to do something (part "A") and then do a direct follow-up test on the design (part "B").

I need two things from this testbench: the results of the test (part "B", passed/failed) and coverage information, but the coverage information should only include part A and explicitly not part B.

I could do the following: run the testbench with part A and B, get the "passed/failed" result of the test and then follow up another simulator run with another testbench, that only includes part A and get the coverage information from that simulation run.

Is there a way to force xcelium to give me the coverage information of only a part of the simulation? Ideally, I would like to write the verilog code of my testbench to look something like this:

• do A
• dump coverage information
• do B

But maybe there is another way to tell xcelium to consider only part of the testbench for the coverage information. I did have a look at the manual, but was not able to find something useful for this problem. Any ideas?

The two macros below introduce new syntax for adding definitions to more than one 'when' determinant value at the same time. The first macro overloads 'extend' keyword and the second is the equivalent for 'when' keyword.

A use example:

extend [HUGE, BIG] packet {
    // definitions that pertain to these subtypes
};

The above code would be expanded in the following (naive) way:

extend HUGE packet {
    // definitions that pertain to these subtypes
};
extend BIG packet {
    // definitions that pertain to these subtypes
};


The macros code:

define 'statement>
       "extend ['name>,...] 'name> ({;...})" as computed {
    for each in 'names> do {
        result = appendf("%sextend %s %s %s;",result,it,'name>,);
    };
    result = appendf("{%s}",result); // required only for versions 6.1.1 or earlier
};

define 'struct_member>
       "when ['name>,...] 'name> ({;...})" as computed {
    for each in 'names> do {
        result = appendf("%swhen %s %s %s;",result,it,'name>,);
    };
    result = appendf("{%s}",result); // required only for versions 6.1.1 or earlier
};

Hello,

 I am working in a digital design. The functional, post synthesis and post P&R without IO pads are all working fine, i.e., functionally and with clean timing reports "no setup/hold violations". I just added the IO pads to the same design, I had to change the timing constraints a bit for the synthesis but I have a clean design at SOC Encounter, i.e., clean DRC and clean timing reports "no setup/hold violations". However, when I perform simulation using the exported net-list from SOC Encounter together with SDF exported from the same tool, I got a lot of hold violations. Consequently, the design is not funcitioning.

Why and how I can overcome or trobleshoot this issue?

In waiting for your feedback and comments.

Regards.

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Dear All,

To design an outphasing combiner, I need to extract the input impedances when the circuit is driven by two sources concurrently with a varying phase-shift and plot them on a Smith Chart. However, I can't find a way to display the simulated S-parameters on a Smith Chart.

The testbench, shown below, consists of two sources set to 50 Ohm with variable phase (PORT0: theta, PORT1: -theta) swept from -90° to 90°. The NPORTs are couplers used to isolate the forward and reflected power at each source, i.e. the S-parameters are:

• S13 = S31 = 1; through path
• S21 = S41 = 1; forward and reflected power
• All other are zero

The testbench is simulated with an "hb" analysis instead of "sp", as the two sources have to be excited simultaneously with varying phase-shift to see their load-modulation effect. The sweep is setup in the "Choosing Analysis" window. The powers of the forward (pXa) and reflected (pXb) waves are found through the "Direct Plot" window, e.g. pvr('hb "/p1a" 0 50.0 '(1)) as the power for p1a, and named P1A_Watt. The S-parameters are then calculated as the reflected power w.r.t. the forward power P1B_Watt/P1A_Watt. This approach is based on a Hot S-parameter testbench from ADS.

At this point I would like to display these S-parameters on a Smith Chart. However, this seemed more challenging than expected. One straightforward method would seem to create an empty Smith Chart window in the Display Window and dragging the S-parameters from the rectangular plot on it, but this just deletes them from the Display Window. Hence my question:

How can I display these S-parameters on a Smith Chart?

Dear all,

Hi!

I'm trying to do a Harmonic Balance (HB) Large-Signal S-Parameter (LSSP) simulation to figure out the input impedance of a nonlinear circuit.

Through this simulation, what I want to know is the large-signal S11 only (not S12, S21 and S22).

So, I have simulated with only single port (PORT0) at input, but LSSP simulation is terminated and output log shows following text.

" Analysis `hb' was terminated prematurely due to an error "

The LSSP simulation does not proceed without second port.

Should I use floating second port (which is not necessary for my circuit) to succeed the LSSP simulation?

Does the LSSP simulation really need two ports?

Below figure is my HB LSSP simulation setup.

Additionally, Periodic S-Parameter (PSP) simulation using HB is succeeded with only single port.

What is the difference between PSP and LSSP simulations?

Hi, newbie here.

We are using AWR Design Enviroment in our university and so I have to install it (OS: Arch Linux)
I installed it in a Windows 10 VM without problems.

When I try to start it prompts "Failed to connect to license server", I guess thats the first problem.

After that when trying to generate my SUL License it will prompt Internal Error -8 (see Image)

I can't find something on Error -8 :/ and overall the available data to the license topic is quit low :/

If someone has a solution for that I would gladly hear about it :)

Hi *,

I am simulating a 32kHz high Q crystal oscillator with a pulse shaping circuit. I set up a PSS analysis using the Shooting Newton engine. I set a beat frequency of 32k and used the crystal output and ground as reference nodes. After the initial transient the amplitude growth was already pretty much settled such that the shooting iterations could continue the job.

My problem is: In 5...10% of my PVT runs the simulator detects a frequency divider in the initial transient simulation. The output log says:

Frequency divided by 3 at node <xxx>

The Estimated oscillating frequency from Tstab Tran is = 11.0193 kHz .

However, the mentioned node is only part of the control logic and is always constant (but it has some ripples and glitches which are all less than 30uV). These glitches spoil my fundamental frequency (11kHz instead of 32kHz). Sometimes the simulator detects a frequency division by 2 or 3 and the mentioned node <xxx> is different depending on PVT - but the node is always a genuine high or low signal inside my control logic.

How can I tell the simulator that there is no frequency divider and it should only observe the given node pair in the PSS analysis setup to estimate the fundamental frequency? I have tried the following workarounds but none of them worked reliably:

- extended/reduced the initial transient simulation time

- decreased accuracy

- preset override with Euler integration method for the initial transient to damp glitches

- tried different initial conditions

- specified various oscillator nodes in the analysis setup form

By the way, I am using Spectre X (version 21.1.0.389.ISR8) with CX accuracy.

Thanks for your support and best regards

Stephan

I get multiple results at the same frequency in a 3-tone simulation.

I try to determine the IP3 of a mixer. I have 3 large signal tones: 0.75 GHz, 1.25 GHz and 1.26 GHz.

At the IM3 frequency of 490 MHz I observe 4 results, see also the screenshot of the table output. The frequencies are exactly the same (even when I subtract 490 MHz by using xval() ).

Which of the values do I have to use to determine the correct IP3?

Is there an option to merge these results?

Hello everybody,

As you can find in the attached image, I am trying to simulate a Colpitts oscillator. However, using pss analysis it shows a high output power. 

My question is where is the problem of my structure or simulation setup?

Best,

Hello everyone,

I am trying to perform a load pull simulation of a transistor to verify some gain calculations I made using its S-parameters. Specifically, I have calculated the optimal conjugate impedances for the input and output to later calculate the power dissipated and transmitted in each stage of the transistor. Then, I only varied the output impedance and recalculated these powers, noticing that the power delivered to the load is lower.

Now, what I want to do is simulate this behavior using the Load Pull simulation. I have taken the model shown in the image, but I believe it is a linear model. My question is: if the chosen model is linear, is the load pull simulation accurate? In the calculations I made, nonlinearities are not considered. I don’t want to take nonlinearities into account.

In short, do you have any ideas on how to verify the calculations made with the transistor’s S-parameters through a load pull simulation?

Can you recommend any transistor model that is nonlinear and also has an S-parameter file?

Thank you very much in advance.

Hello everyone,

For my cross-coupled oscillator design, I have a problem with stability analysis. Based on my achieved results which are attached, where is my design problem?

Best,

https://ibb.co/bgKFP4N

https://ibb.co/3FGRLmV

https://ibb.co/pwSZDSF

Hi everyone,

I'm currently working on my thesis, which involves a beamformer system using CMOS 65nm technology. I'm trying to use the EMX tool for EM simulation but have encountered a few problems. Before diving into my questions about EMX, let me briefly explain how I conduct EM simulations with other software (ADS).

In ADS, I use the EM simulator with the Momentum microwave engine. However, my EM layout is quite large, and the mesh generated is extremely detailed, making it difficult to simulate the entire system. As a workaround, I divide the system into smaller parts and simulate each one individually. I've attached a snapshot of my setup, which includes an amplifier and a 1-to-2 Wilkinson power divider. I've separated these circuits and placed pins to facilitate EM simulations for each. I also placed ground pins at the boundaries of each circuit to connect them to the ground plane.

Here’s the link to the image (I'm unable to upload it due to an error): https://drive.google.com/file/d/13Qn4-DvMBj_K1JQLXrTWaWZ8uaLJr15u/view?usp=sharing

Now, moving on to EMX (version 6.3). For a maximum frequency of 31 GHz, I set the edge mesh = thickness = 0.4 µm (approximately the skin depth). However, when I simulate the circuit (amplifier + divider), the mesh on the ground plane becomes very dense, which makes running the simulation impossible due to excessive memory requirements. I reverted to my ADS approach and divided the circuit into two parts, placing ports to connect them. Unfortunately, EMX doesn't allow me to place multiple edge ports on the same edge for the ground plane, which has left me confused. Here are a couple of questions I have:

1. Is breaking the circuit into smaller parts a valid approach? Given the large ground plane, the mesh size for the ground is significant, making simulations challenging. Are there any methods to manage this issue?

2. Regarding the ground pins, why can't I place multiple edge ports to connect the ground planes of both circuits as I did in ADS? If this approach is incorrect, could you suggest alternative methods for simulating individual circuits and connecting them to estimate system performance?

Any insights would be greatly appreciated. Thank you in advance for your help!

Hello Everybody

Recently, I want to design a high output Power Amplifier at 2.4GHz using TSMC 1P6M CMOS Bulk Process. I use its nmos_rf_25_6t transistor model to determine the approximate mosfet size

I use the most common Common-Source Differential Amplifier topology with neutralizing capacitor to improve its stability and power gain performance

Because I want to output large power, the size of mosfet is very large, the gate width is about 2mm, when I perform harmonic balance analysis, everything is alright, the OP1dB is about 28dBm (0.63Watt)

But When I perform Transient simulation, the magnitude of voltage and current waveform at the saturation point is too small, for voltgae, Vpeaking is about 50mV, for current, Ipeaking is about 5mA

I assume some reasons: the bsim4 model is not complete/ the virtuoso version is wrong (My virtuoso version is IC6.1.7-64b.500.21)/the spectre version is wrong (spectre version is 15.1.0 32bit)/the MMSIM version is wrong/Transient Simulation setting is wrong (the algorithm is select gear2only, but when I select other, like: trap, the results have no difference), the maxstep I set 5ps, minstep I set 2ps to improve simulation speed, I think this step is much smaller than the fundamental period (1/2.4e9≈416ps)

I have no idea how to solve this problem, please help me! Thank you very very much!

Read through this blog to know more about the new Reliability Report view in Virtuoso ADE Assembler and Virtuoso ADE Explorer.(read more)

Hi

the signal SPI_SCLK belongs to TWO Spacing CLASSES: CLS_SP_SPI and CLS_SP_SPI_CLOCK

I then assign TWO different SPACING RULES to each class : CLS_SP_SPI  > 2H and CLS_SP_SPI_CLOCK > 3.5H

Which SPACING RULE will inherit the signal SPI_SCLK ??

Is it possible to manually define the PRIORITY on Design Rules ??

The default behaviour of Place replicate update is to select every new net item connected to the replicate module. This leads to an abundant number of clines, vias and shapes being selected, most of which I don't want to add to the replicate group. It is very tedious to unselect all these items and more often than not, I miss one or two items and then end up with a via or cline in a completely different place on the board or outside of the board.

Is there a way to change this rather annoying behaviour? I haven't found any way to disable it or to batch deselect everything the tool has decided to add to the replicate group.

The question has been asked before, but it didn't get any answers and the thread is now locked.

/F

Hi

I have fixed a SPACING RULE (SP1) for a CLASS_DIFF_PAIR whereas for via associated to the net (DP_VIA), the DISTANCE > 60mils respect to ANY other vias (PTH, BB, TEST vias)

Now my problem is that this rules should NOT be applied for GND VIAS (STICHING VIA) which must be placed at a distance < 40mils respect to DP_VIA

How to create an exemption to the SPACING RULE (SP1)?

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