Principles of Top-Down Mixed-Signal Design
Roles and Responsibilities
implementing the individual blocks, such as circuit design and layout. They are respon- sible for assuring that their blocks meet the required specifications, and that they work properly when embedded in the overall system. As such, they are expected to verify their designs in the context of the whole system using mixed-level simulation. Block designers also often take responsibility for building the behavioral models of their blocks that are shared with the rest of the design team.
Modeling engineers may be, but are not usually, dedicated to individual projects. They are often used to develop the sophisticated models that would be difficult for the other members of the team. They are made available to the design teams with the recognition that modeling is a skill and discipline that is distinct from design, and that most design engineers do not have the knowledge or experience to create complex or difficult mod- els.
6.6 Test Engineers
Test engineers work with the team lead and system and top-level designers and occa- sionally with the block designers to develop a test plan, and to specify self-test strate- gies, and to write the test programs. They may be shared between multiple projects, but should become involved at the onset of the project in order to assure that the chip is as testable as possible, and to reduce the time to market. For example, once the system- level model is available, the development of the test programs can begin. In this way, a formerly serial task that occurred after silicon became available can be done in parallel with the block design and assembly.
6.7 Senior Architect
The senior architect acts as a consultant to multiple projects. Depending on his or her experience, he or she consults on aspects of the system-level, architectural-level, or tran- sistor-level design. Optionally works on the overall system and block specifications, and the test plan, with the team lead, the top-level designer, and system designer.
The program manager would coordinate with the team lead to manage the schedule and resources of the project. He or she would also manage the relationship with the “cus- tomer” as well has handle various financial responsibilities. Generally, the program manager manages multiple projects.
Responsibility for writing behavioral models varies depending on the complexity of the project and the type of the block. For simple blocks, the block designer usually writes the model. This is very practical because the model and its corresponding circuit share the same test bench. The block designer uses the model to efficiently construct and debug the test bench. Once the circuit is available, the block designer compares the behavior of the model against the block, and makes adjustments to improve its fidelity.
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