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 Custom Layout Insights
Graham Etchells, Director of Product Marketing at Synopsys
Graham Etchells, Director of Product Marketing at Synopsys
Graham Etchells started in EDA before it was termed EDA. He has held marketing and sales positions at several companies and has been chasing the holy grail of analog/custom layout automation ever since he was a marketing director at Cadence in the mid-1990s. He says past experience indicates we may … More »

Reducing Analog Cell Layout Time with the Symbolic Editor

 
December 1st, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

Hello again!

In the last blog post I profiled the use of Custom Compiler’s Symbolic Editor for rapid digital cell layout.

In this post, we will tackle analog cell layout and show some more of the Symbolic Editor features that enable analog layout engineers to complete their layout in minutes vs. hours.

As with the digital cell layout, engineers can take advantage of the Symbolic Editor’s ability to define multiple P and N row pairs, as shown in Figure 1.

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Figure 1. Multiple Row Pairs

The preview window shows how the layout will look when realized on the layout canvas. In this example, it is clear that in order to make the design more compact, the larger transistors need to be folded.

Folding the transistors is very easy using the Symbolic Editor. Options on the toolbar allow the designer to fold the transistor by specifying either the number of segments desired or by specifying a width threshold. Once the option is set, all the layout engineer has to do is simply select the appropriate devices and have them folded such that the transistors fit neatly in the rows. Figure 2 shows how the design looks before and after folding.

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Figure 2. Before and After Folding

Analog designs are very sensitive to process variation, noise and other manufacturing variances. In order to mitigate the impact of these variances on critical pieces of circuitry, layout engineers use complex interdigitation patterns in addition to other layout techniques. This is a critical practice for analog design, because the effects of the variances, if not accounted for, can lead to a non-functioning piece of circuitry.

The Symbolic Editor provides a simple way to implement these complex patterns via the Pattern Generator. As well as being able to specify your own patterns, the Pattern Generator also includes a library of built-in patterns that can be used to interdigitate devices in a specific order. Take a differential pair, for example. The layout engineer can choose from a variety of different patterns as shown in Figure 3.

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Figure 3. Pattern Generator

The preview window makes it easy to see how the layout will look with the chosen pattern and, once the engineer is happy with the choice, s/he simply realizes the layout on the canvas. Figure 4 shows the results of choosing a Common Centroid pattern. With no constraints to enter, no code to write, layout is done in minutes vs. hours.

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Figure 4. Highlighted Devices as Part of a Common Centroid Pattern

Transistors are not the only devices that can take advantage of the Symbolic Editor. In the automotive world, it is often necessary to lay out banks of resistors. This is something the Symbolic Editor can also help with. Resistors can be chained serially in a variety of different routing patterns.

Using the Symbolic Editor allows the layout engineer to make simple graphical choices of how the layout needs to look and then have the detailed placement taken care of by the placement engine. It makes it easy to add or remove placement rows and columns, as well as insert dummy devices. Figure 6 shows the completed symbolic layout of two resistor banks with automatic insertion of dummies.

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Figure 6. Completed Symbolic Layout of Two Resistor Banks with Automatic Insertion of Dummies

Generating devices and placing them such that they meet all the design rules and produce a robust working design is about 30% of the time spent doing layout. Using a layout assistant like the Symbolic Editor really speeds this task up and makes the layout engineer much more productive. Synopsys has invested heavily in this technology over a period of 5+ years, such that we can address a broad range of design applications, unlike the recent offerings from other EDA vendors. Applicable to both FinFET and established planar CMOS nodes, the Symbolic Editor makes analog cell layout quick and easy.

To learn more about how the Symbolic Editor can help to rapidly create analog cells, check out Custom Compiler Webisode #6 that shows the Symbolic Editor in action.

Rapid Custom Digital Cell Layout with the Symbolic Editor

 
November 3rd, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

In the ‘Custom Compiler Layout Assistants (Part 1)’ blog post, I profiled the use of the symbolic editor and how it makes placing devices that need to be in a specific interdigitated pattern (for example, a differential pair) very easy. With no constraints to enter and no code to write, layout is done in minutes vs. hours.

However, there is a lot more to the symbolic editor than the ability to simplify interdigitation. One good example is the ability to define multiple P and N row pairs and then symbolically chain and fold the transistors such that you get them to fit neatly in the rows. This is a key feature that allows you to not only control the aspect ratio of the design, but to very rapidly create a custom digital cell layout, as shown in Figure 1.

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Figure 1. Multiple Row Pairs

Read the rest of Rapid Custom Digital Cell Layout with the Symbolic Editor

Custom Compiler In-Design Assistants (Part 3)

 
September 20th, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

In the blog ‘Custom Compiler In-Design Assistants (Part 2)’, I outlined how we can use StarRC to report capacitances on critical nets in the layout even when the design is still in flux and not completely LVS-clean. In addition to capacitance reports, we also showed resistance reporting which is critical for FinFET-based layouts. At advanced nodes, the impact of parasitics, electromigration (EM) and restricted design rules drive critical layout choices. Interconnect that does not meet resistance, or EM criteria and unbalanced capacitances on matched nets, can and often does adversely impact layout schedules. So the earlier in the layout phase the layout engineer can address these issues, the sooner he or she can close the design.

EM in particular is a notorious problem in the FinFET process due to the high drive of the transistors and thin metals. So let’s say, for example, the layout engineer has to route a critical net which could be susceptible to the impact of EM. This is a non-trivial task that could be quite challenging. However, if you use Custom Compiler, there are some very cool capabilities that make laying out interconnect that meets EM criteria very quick and very easy.

Read the rest of Custom Compiler In-Design Assistants (Part 3)

Seeing is Believing

 
August 28th, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

In past blogs I provided some insights into the differences between FinFET and planar CMOS designs and why layout engineers need to take these differences seriously.

In introducing Custom Compiler, Synopsys has taken a fresh approach to custom design that employs visually-assisted automation technologies to speed up common design tasks, reduce iterations, and enable reuse. But sometimes, it’s not enough to simply say that a new tool is great–engineers need to see it to believe it.

As such, Synopsys has developed a collection of short technical webisodes focusing on the unique features of Custom Compiler’s visually-assisted automation technologies that can shorten FinFET design tasks from days to hours.
The first webisode highlights how the symbolic editor enables layout engineers to create and optimize device placements at a high level of abstraction. We show how to rapidly create complex layout patterns for FinFET devices, as well as multi-row placements for PMOS and NMOS transistors, at a symbolic level without having to worry about design rules, connectivity or parameter values.
The second webisode highlights how Custom Compiler’s routing assistant enables layout engineers to route hundreds of connections with a simple click and drag of the mouse. We show how to rapidly route complex interdigitated layouts of FinFET devices, as well as simple multi-row placements for PMOS and NMOS transistors.

Read the rest of Seeing is Believing

Custom Compiler at DAC 2016

 
August 8th, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

DAC 2016 saw the first Synopsys custom design luncheon to feature Custom Compiler. It was a sold out event with 150 customer attendees eager to hear from Synopsys and other customers about how Synopsys is progressing in the custom design space. Antun Domic, Executive VP and General Manager of Synopsys’ Design Group moderated the event which included speakers from STMicroelectronics, GSI Technology, Samsung Foundry and the Synopsys IP team. For those of you who missed the live event, following is a short summary of the event highlights.

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Antun opened the proceedings and presented Synopsys’ fresh approach to custom layout with Custom Compiler. He shared details of the pioneering visually-assisted automation technologies that speed up custom design tasks, reduce iterations and enable reuse.

Antun then went on to introduce each of the customer speakers who related their experiences using Custom Compiler and how visually-assisted automation helped them reduce their layout efforts from days to hours.

Read the rest of Custom Compiler at DAC 2016

Custom Compiler In-Design Assistants (Part 2)

 
July 14th, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

Planning which metal shape goes on which color (mask) is key when designing in a FinFET process, especially when propagating connections through the layout hierarchy. In addition, highly matched signals such as complementary clocks must be assigned to the same color, as routes on different masks have different resistances. So how do we ensure we are keeping things in order with respect to the matching of resistance and capacitance?

Custom Compiler’s In-Design assistants include a built-in engine that computes resistance of a net from a single source to a single destination or multiple destinations. It is an interactive tool that can be run often during the layout process, has a simple use model and a fast response time. To report the resistance of a net, the layout engineer simply selects the net of interest from either the layout, the design navigator or the schematic. The next step is to invoke the resistance report command which pops up in the electrical report menu. The report type is set to “Resistance” and the source and destination points are entered.  The report is run and the results are populated in the Electrical Reporter pane.
Read the rest of Custom Compiler In-Design Assistants (Part 2)

Custom Compiler In-Design Assistants (Part 1)

 
June 18th, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

On-line Design Rule Checking (DRC) is nothing new. The technology has been in use for years in a variety of different layout editors and yet nearly every layout engineer has a love/hate relationship with it. Why? Well it really comes down to the use model and the responsiveness of the application.

At the beginning of the design process, layout engineers love on-line DRC. But as the design progresses, the relationship begins to sour. The problem is that as the layout gets bigger and more complex, the performance invariably starts to fall off until it reaches a point where it becomes unacceptable and the layout engineer simply turns it off and resorts to running the occasional batch checks.

To really be effective, on-line DRC has to be an interactive tool that is run often during the layout process, so, as such it needs to have a simple use model and have a fast response. The engine needs to be ‘built-in’ to deliver the required performance and the feedback needs to be comprehensive enough to enable the layout engineer to quickly fix the violation.
Read the rest of Custom Compiler In-Design Assistants (Part 1)

Custom Compiler Layout Assistants (Part 2)

 
June 15th, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

To all of you who attended DAC last week in Austin, TX–welcome back! I hope you were among the 175+ people who attended the Custom Compiler lunch event on Tuesday, June 7 to hear directly from engineers at GSI Technology, Samsung, STMicroelectronics and Synopsys’ IP group who described how Custom Compiler’s visually-assisted automation improves their productivity for both FinFET and established-node designs. We’ll be posting a videolog of the presentations on the Synopsys web site soon for those who missed the live event.

In the last blog I detailed the Symbolic Editor Layout Assistant and showed how the layout engineer can make simple graphical choices of how the layout needs to look and then have the placement taken care of by a placement engine. In this post I will outline another layout assistant: the Routing Assistant. The routing task is one that absolutely screams out for an automated approach, however past efforts have required a great deal of text-based constraints to get anything near to what you really want.

Custom Compiler’s Routing Assistant is a perfect combination of user guidance and automation. It’s a visually-assisted approach that allows the layout engineer to simply click on the starting point of the route and then drag the cursor in the direction they want the routing to follow. As the cursor moves along, behind the scenes the routing engine searches for connections that it can make. When it finds a connection it automatically taps to the pin without the layout engineer having to enter a mouse click. The user simply guides the router with the mouse and it fills in the routing details automatically.
Read the rest of Custom Compiler Layout Assistants (Part 2)

Custom Compiler Layout Assistants (Part 1)

 
June 1st, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

As mentioned previously, on March 30th Silicon Valley was buzzing with excitement. Synopsys revealed Custom Compiler, a fresh approach to custom design that employs visually-assisted automation technologies to speed up common design tasks, reduce iterations and enable reuse at the SNUG Silicon Valley event. During this event, the R&D folks did a walkthrough of the technology ‘under-the-hood’ and showed the audience some cool layout assistants that leverage the graphical use model familiar to layout designers while eliminating the need to write complicated code and constraints. [Click here to view the videolog of the SNUG event.]

One of the layout assistants that was shown was the symbolic editor. This really is a must-have assistant when it comes to placing devices that need to be in a specific interdigitated pattern, like a differential pair. In the schematic, it is two symbols, but in the layout it could be hundreds of devices. The symbolic editor allows device placement to be edited in an easy and graphical manner and comes with a rich collection of predefined placement patterns. If you find a placement pattern you like, you can simply use it as-is and the symbolic editor will generate a correct-by-construction placement that you can instantiate in your layout. If you don’t find an exact match, you can easily use a pattern that is similar to what you need and rearrange the placement pattern graphically. No constraints to enter, no code to write and layout is done in minutes vs. hours.
Read the rest of Custom Compiler Layout Assistants (Part 1)

A Personal Invitation

 
May 23rd, 2016 by Graham Etchells, Director of Product Marketing at Synopsys

I just wanted to take a moment to personally invite you to attend Synopsys’ Custom Compiler lunch event at DAC 2016 on Tuesday, June 7 in Austin, TX. At this event, engineers from GSI Technology, Samsung, STMicroelectronics, and Synopsys’ IP Group will showcase their experiences using the new Custom Compiler custom IC design tool with Visually-assisted Automation technologies.

As you’ll recall, Synopsys unveiled Custom Compiler on March 30 of this year at SNUG Silicon Valley. Custom Compiler is a new custom IC design solution that closes the FinFET productivity gap by cutting custom layout tasks from days to hours. It offers a fresh approach to custom design that employs Visually-assisted Automation technologies to speed up common design tasks, reduce iterations and enable reuse. Visually-assisted Automation technologies are a unique set of productivity aids that leverage the graphical use model familiar to layout designers while eliminating the need to write complicated code and constraints.
Read the rest of A Personal Invitation

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