On July 2 Cadence announced its acquisition of Sigrity, a provider of signal integrity and power network analysis tools for PCB and IC package design. Cadence already has some technology in these areas, and many Allegro and OrCAD customers use Sigrity tools today. So why buy Sigrity, and why make this move now?
Following a discussion with Brad Griffin, product marketing director for PCB and IC packaging at Cadence, I can say this acquisition may represent a turning point for PCB analysis flows. Cadence currently provides technology for signal integrity (SI) and power integrity (PI) exploration. This technology is well integrated into PCB and IC package design flows, and is typically used by EEs and designers. Sigrity, on the other hand, offers technically detailed, post-route analysis tools that are most often used by experts as they sign off board and package designs.
What happens when Sigrity tools are fully integrated into the Allegro and OrCAD environments, and can offer the same ease of use as the current Cadence SI/PI exploration tools? "I think we can expand the Sigrity user space to more EE generalists and not just serve experts who are responsible for a final signoff solution," Griffin said. Thus, the real legacy of the Sigrity acquisition may be one that brings advanced analysis tools further up into the PCB and IC package design flows, where they can be leveraged by designers who don't need to step out of that flow or have special expertise.
What Sigrity Adds
But let's back up for a moment. Why is there a need for advanced SI/PI analysis tools? One reason is that multi-gigabit systems are now being designed, and they really need a more advanced analysis capability than Cadence can offer with its current SI/PI solutions. PCI Express 3.0, for example, runs at 8 Gbits/second and has a "back channel" feature not currently modeled by the Cadence PCB analysis flow. Sigrity technology, Griffin noted, helps fill that gap.
So what do Sigrity and Cadence offer in SI/PI, respectively? The best answer is provided by the following illustration, which shows Cadence and Sigrity solutions for exploration, analysis, power design, and verification signoff. (You can click on the image to get a larger view, then use your browser's back button to return). The bottom line, Griffin noted, is that Cadence can now offer "a full front-to-back PI and SI solution for both PCB and packaging."
Some Allegro and OrCAD users are already running Sigrity tools, but integration is lacking. Designers have to close Allegro, extract data from the binary files in the Allegro database, and convert to an ASCII format that can be read into a Sigrity tool. That tool will have a different user interface than Allegro. In contrast, the Cadence SI/PI capabilities are so well integrated that one can click on a trace and immediately pull up a signal integrity analysis for a net. "Over time, people will see the same level of integration using advanced Sigrity engines," Griffin said.
Sigrity also brings in some capabilities that are new to the Cadence PCB analysis flow, such as:
- PCIe 3.0 back channel modeling and simulation
- DDR3/DDR4 power aware modeling, enabling simultaneous switching noise (SSN) analysis
- Electrical and thermal co-simulation
- Integration with transistor-level simulators that support SSN closure
- Integrated full-wave 3D electromagnetic (EM) modeling
- Integrated full IC package modeling
- Automated power delivery network (PDN) analysis that can place decoupling capacitors for the best cost/performance ratio
Key Sigrity Products
If you go to the Sigrity web site you will see a listing of 11 products. According to Griffin, the "flagship" products are these:
A complete PCB/package layout based time domain EM simulation tool for signal integrity, power integrity and design-stage EMI analysis. It supports advanced layout checking for design sign-off and debug.
An advanced signal integrity, power integrity and design-stage EMI solution. Supports S-parameter model extraction and provides robust frequency domain simulation for entire IC package and PCB designs.
A fast IC package RLC extraction and assessment solution with an option to generate highly accurate broadband models. Supports a broad range of package types including BGA, SiP and leadframe designs.
The company gains much of its competitive edge from its SSN analysis capabilities. "If you take PowerSI and SPEED2000 together, you are able to extract very large, complicated DDR3 and DDR4 networks and simulate them using power-aware IBIS models to get a very accurate analysis using behavioral models," Griffin said.
Griffin noted that Sigrity has some emerging technology in full-wave 3D EM modeling that Cadence intends to more fully develop. He also said that the Sigrity technology will be useful for 2.5D silicon interposer packaging, and that "we believe the technology should be applicable" to 3D die stacks. Meanwhile, Sigrity tools will continue to be available for third-party flows from Mentor Graphics and Zuken.
The Sigrity acquisition was completed July 2, 2012 at a purchase price of $80 million. Most Sigrity employees are expected to join Cadence. Jaiyuan Fang, founder and CEO of Sigrity, will join Cadence and report to A.J. Incorvaia, vice president of R&D for the Allegro and OrCAD PCB and IC packaging technologies.