Pre-Layout Analysis for High-Speed Design, Part 1

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In my last post, we discussed the big picture of high-speed design analysis phases. In this post, we will discuss the first phase, pre-layout analysis for high-speed design.

Pre-Layout Analysis

During system planning and circuit design, it is important to evaluate whether our designs are producible, stable, and cost-effective, especially when working with high-speed PCB designs.

With high-speed PCB designs, we know that the connected wires become the transmission-lines. In other words, the electrical functions might not be established even if we connected the traces from one end to another.

In the pre-layout analysis phase, we will focus on solving the following issues:

  • Could we implement the concept from the system and circuit designs into a real product?
  • How stable will the product be?
  • How cost-effective is the product versus its performance and functionality?

Design Producibility

High-speed PCB designs may face new challenges due to transmission lines, fast signal switching rates, and small product size (portable and miniature). From a signal integrity point of view, an engineer needs to make sure the product can be producible while retaining its required functionality. To achieve this, EDA tools must provide a topology builder, along with simulation capabilities.

Product Stability

Stability verification is an essential task in the post-layout phase that we will discuss later. But to start, stability simulation is critical in the pre-layout analysis phase. For example, we might find a different set of chips that works more stable than our original selection. Or we might identify a particular via structure to help improve the signal qualities. Pre-layout signal integrity simulation and error bit analysis help mitigate the stability issues found after PCB layout.

Cost-effectiveness

The overall cost of a product includes design cost, material cost, process cost, and manufacturing cost. High-speed design analysis can help the designer select more functional parts, cheaper components, easier production processes, and more reusable product blocks. Similarly, what-if simulation plays a vital role in analyzing a product’s cost-effectiveness by making sure it can maintain a good ratio of cost, stability, and functionality.

CR-8000 Pre-Layout Analysis Capabilities

Zuken’s CR-8000 tool suite covers all the necessary functionalities for the pre-layout analysis phase. Both CR-8000 Design Gateway (schematic design) and CR-8000 Design Force (PCB and package layout) link to the CR-8000 Electrical Editor for concurrent analysis. CR-8000 can verify a design’s producibility while enabling what-if analysis to improve cost-effectiveness and stability.

This video shows how Electrical Editor seamlessly extracts a schematic net from Design Gateway; how to change the topology structure for the DRR4 clock nets; and how to use the Conductor Configuration Manager parameter sweep feature for trace layout planning.

CR-8000 Electrical Editor can sweep the parameters for trace width, distance, thickness, etc. It can also sweep the trace length for part spacing and route length planning.

High-Speed Design Pre-Layout Analysis. Chart showing transmission-line length sweeping function for what-ifs
Figure 1: Transmission-line length sweeping function for what-ifs.

Electrical Editor can also perform component what-ifs by swapping the component models to identify the most reliable and cost-effective part solutions for product manufacturing.

High-Speed Design Pre-Layout Analysis. Chart showing Model swapping function for what-ifs.
Figure 2: Model swapping function for what-ifs.

CR-8000 Design Force also contains embedded pre-layout analysis features. The most significant advantage of performing pre-layout analysis in Design Force is the ability to extract nets that contain the layer stack information. As a result, the engineer can use the layer stack information as a reference for more accurate PCB layout planning.

Alt: High-Speed Design Pre-Layout Analysis. Screenshot showing CR-8000 Design Force extracting net topology from a board design.
Figure 3: Extract net topology from CR-8000 Design Force

Alt: High-Speed Design Pre-Layout Analysis. Screenshot showing layer stack information in the transmission line configuration tool.
Figure 4: Transmission line configuration tool contains layer stack information

Conclusion

To sum up, the pre-layout analysis phase is valuable for early-stage product design verification and for improving product functionality and stability. Most importantly, this phase can increase a product’s profitability by improving its cost-effectiveness.

Zuken’s CR-8000 tool suite provides many pre-layout analysis functionalities from schematic to PCB layout. So, understanding the pre-layout phase with CR-8000 capabilities can help you speed up the design process, improve product quality, and reduce process and manufacturing costs.

In part 2 of this series, we will discuss the constraint-driven methodology and applications in the pre-layout analysis phase. Stay tuned!

 

References:

Lance Wang
Lance Wang
Lance Wang is a solutions architect at the Zuken SOZO Center. He supports the CR-8000 product line, mainly focusing on high-speed PCB design and signal integrity features. When not behind the keyboard or in front of customers, he is a Tom Brady fan and enjoys playing ping pong in his spare time.