Electronic Design - Concurrent design strategy for high-speed PCB

The overall process analysis of PCB design can be roughly divided into the following stages: netlist import, package library building, main design, physical and electrical constraint design, layout, wiring, design review, and design output. For a complex design, from the task itself, layout and wiring are relatively onerous, especially wiring. From long-term practical experience, manual wiring of important signals is still the main form of wiring.

Considering the complexity and arduousness of the PCB layout and routing task process, a parallel design method is considered. Parallel design methods for layout and routing are basically similar, with different goals and focuses. The following takes layout as an example, and a brief description will be made on the special points of parallel wiring design.

Task analysis and decomposition

The starting point of layout analysis is structural design constraints and circuit topology analysis. Structural design constraints include frame shape and size requirements, mounting holes and special component positioning and height limit requirements, and regional use constraints.

Consider a typical design example, taking mobile phone board design as an example. From the observation of the circuit topology, the signal characteristics of each part have obvious differences in the layout requirements. The layout of each component will be expanded according to the signal flow, and the design requirements such as shielding and electromagnetic compatibility (EMC) should be taken into consideration.

For product reliability and stability considerations, signal integrity (SI) issues must also be considered. Based on the type of circuit topology, the appropriate space is planned for each component, and appropriate engineers are arranged for parallel design and layout.

Role arrangement

Consider the following task decomposition of parallel design layout:

1. Communication protocol related groups, including radio frequency components (power amplifier/transceiver/inverter, etc.), analog-digital hybrid components, conventional analog/logic components, digital baseband processors, etc.;

2. Application related groups, including LCD/backlight driver, image processing engine, application processor, memory (RAM), flash memory (Flash), storage (SDCard), etc.;

3. Common signal related groups, including interfaces, power supply and power management, clock components, etc.

It is assumed that each of the parallel phases is assumed and completed by an engineer. Then there are the following role assignments: Engineer A is responsible for layout design and communication protocol group layout; Engineer B is responsible for application-related group layout; Engineer C is responsible for public signal-related group layout. The principle of role arrangement is to focus on the skills and expertise of each engineer.

Layout concurrent design

Each engineer (including Engineer A) carries out the layout according to their respective layout areas and related requirements. After the layout is completed, the devices that are not related to their tasks are deleted. Export the respective sub-layout files through the PCB tool software and submit them to the responsible engineer A.

After engineer A receives each sub-layout file, he still imports the sub-layout files to his own sub-layout file in turn through the PCB tool software. Engineer A adjusts and optimizes the layout according to the design requirements.

Parallel design of wiring

The starting point of wiring analysis is generally the analysis of the electrical signal of the circuit topology. Electrical signals can be divided into two types: critical signals (signals with strict electrical constraints) and non-critical signals.

Still considering the aforementioned mobile phone board design example, there are obvious differences in the wiring requirements of each part. The wiring of each component still needs to be expanded according to the layout elements and signal flow, while taking into account various electrical performance design requirements.

For the above-mentioned typical design examples, the following parallel design wiring method can be considered: the circuit topology type (that is, the required area division) and the signal flow are expanded to determine the wiring priority. For wiring with high priority (often with a large workload), wiring is given priority to ensure performance and progress

Consider assigning parallel design tasks in high-priority wiring tasks, and then the responsible engineer will complete and organize them. In addition, the use of tools is different from the layout stage. The exported and imported files in the wiring stage will be sub-design files.

Summary of this article

After analyzing the principle of a mobile phone board design example, this article describes the method of parallel design. Through the division of tasks and the combination of tools, the operation of high-speed PCB parallel design is realized, which not only achieves the complementary advantages of resources, but also ensures the design quality and time schedule. Require.