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Assurance Process for Complex Electronics
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Life Cycle

Preliminary Design

Preliminary Design Phase

This Overview page for the Preliminary Design Phase contains the following sections:


The preliminary design phase may also be known as conceptual design or architectural design . During this phase, the high-level design concept is created, which will implement the complex electronics requirements. This design concept may be expressed as functional block diagrams, design and architecture descriptions, sketches, and/or behavioral HDL (hardware description language).

The objective of the design phases (preliminary and detailed) is to create a design that will correctly and completely implement the requirements. For the preliminary phase, the main goal is to map out how the complex electronics will perform the functions specified in the requirements, within the constraints of the device, the defined interfaces, and the environment the device will operate within. At this phase, the designer needs to maintain a systems perspective and look at the complex electronics operations in concert with the rest of the system. Now is the time to identify inconsistencies, misunderstandings, and ambiguities.

The objective of design assurance is to verify that the design does implement all the requirements, and that it implements nothing but the requirements. Any deviations (such as additional functionality that may indicate a missed requirement) are fed back to the requirements engineering process.

The main design activities for the preliminary design phase are:

  1. Create the high-level design description.
  2. Identify major components, including third-party IP modules or cores.
  3. Any derived requirements that result from the process are fed back to the requirements engineering process
  4. Any omissions or errors are resolved
  5. Include reliability, maintenance, and test features that are necessary to meet performance and quality requirements, and to ensure that testing can be performed to verify the requirements.
  6. Identify constraints on other system elements that are a result of this high-level design.

This assurance process for complex electronics assumes that complex electronics requirements have been developed, assessed, and baselined (formalized). In reality, these requirements may be included in a higher-level assembly requirements specification, such as a circuit board or sub-system. The requirements for complex electronics are likely to be a work in progress, as design decisions in other areas of the system influence the functions the CE device will perform. Requirements management will be an important process throughout the design, implementation, and test phases.

Preliminary Design Process

The diagram below shows the preliminary design process for complex electronics. The Develop Preliminary Design page describes the engineering process to create the design. The Assurance Process page describes the activities to assess and verify the design.

Entrance Criteria:

The following criteria should be met prior to beginning the development and assurance of the complex electronics preliminary (architectural) design.

  • The complex electronics requirements should be complete and baselined. In reality, the requirements must be sufficiently complete to allow the design to be started.
  • The Configuration Management process is defined and in operation.
  • The Assurance process is defined and operational. The assurance engineers responsible for the complex electronics have been identified.
  • The hardware description language (HDL) and toolset have been selected. HDL coding guidelines for the project are complete.
  • Design guidelines are specified.

Exit Criteria:

At the end of the preliminary design phase, the following criteria should be met:

  • Requirements for complex electronics are complete, with only limited exceptions.
  • The top level design architecture is approved.
  • A preliminary design document has been created
  • Behavioral simulation has been performed (if required)
  • Models and test benches required as inputs to the Detailed Design phase (e.g., synthesizable RTL models) are generated.

Roles and Responsibilities

The table below describes typical activities during the Preliminary Design Phase for both engineers and assurance personnel.

Preliminary Design Phase


Typical Activities

Systems Engineer

Ensure that design decisions at the sub-system level (including the complex electronics) are consistent with the overall system design. Manage the interfaces between the various system elements. Ensure that the sub-system designs will be verifiable. Start system integration planning.

Electronics Designer

Assess the complex electronics architecture for compatibility with interfacing electronics. Plan for integration of the complex electronics with supporting electronics. Ensure the CE is testable in-circuit.

CE specialist (optional)

Create the architectural design for the complex electronics. Create the test bench to evaluate the design. Perform behavioral simulations. Work with the systems engineer to resolve interface issues.

System Safety

If the complex electronics is safety related, review the architectural design for proper implementation of safety features. Ensure that the CE does not create any new hazards.

CE/Quality Assurance

Assess the complex electronics design against the requirements. Perform other analyses required by the CE classification. Ensure that the documented design process is in place and is followed by the design team.

Preliminary Design Site Map

The table below describes the information contained on the other pages in the Preliminary Design section.

Preliminary Design Site Map

Overview This page

Develop Preliminary Design

The process of developing the architectural design for complex electronics.

Assurance Process

Describes the assurance process for complex electronics preliminary design, with links to specific techniques.

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Last Updated: 10/19/2009