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The process of circuit design can cover systems ranging from complex electronic systems all the way down to the individual transistors within an integrated circuit. For simple circuits the design process can often be done by one person without needing a planned or structured design process, but for more complex designs, teams of designers following a systematic approach with intelligently guided computer simulation are becoming increasingly common. In integrated circuit design automation, the term "circuit design" often refers to the step of the design cycle which outputs the schematics of the integrated circuit. Typically this is the step between logic design and physical design.〔Naveed Sherwani, "Algorithms for VLSI Physical Design Automation"〕 Formal circuit design usually involves the following stages: *sometimes, writing the requirement specification after liaising with the customer *writing a technical proposal to meet the requirements of the customer specification *synthesising on paper a schematic circuit diagram, an abstract electrical or electronic circuit that will meet the specifications *calculating the component values to meet the operating specifications under specified conditions *performing simulations to verify the correctness of the design *building a breadboard or other prototype version of the design and testing against specification *making any alterations to the circuit to achieve compliance *choosing a method of construction as well as all the parts and materials to be used *presenting component and layout information to draughtspersons, and layout and mechanical engineers, for prototype production *testing or type-testing a number of prototypes to ensure compliance with customer requirements *signing and approving the final manufacturing drawings *post-design services (obsolescence of components etc.) == Specification == The process of circuit design begins with the specification, which states the functionality that the finished design must provide, but does not indicate how it is to be achieved .〔http://www.informit.com/articles/article.aspx?p=392278〕 The initial specification is basically a technically detailed description of what the customer wants the finished circuit to achieve and can include a variety of electrical requirements, such as what signals the circuit will receive, what signals it must output, what power supplies are available and how much power it is permitted to consume. The specification can (and normally does) also set some of the physical parameters that the design must meet, such as size, weight, moisture resistance, temperature range, thermal output, vibration tolerance and acceleration tolerance.〔A. Tajalli, et al., "Design trade-offs in ultra-low-power digital nanoscale CMOS," IEEE TCAS-I 2011.〕 As the design process progresses the designer(s) will frequently return to the specification and alter it to take account of the progress of the design. This can involve tightening specifications that the customer has supplied, and adding tests that the circuit must pass in order to be accepted. These additional specifications will often be used in the verification of a design. Changes that conflict with or modify the customer's original specifications will almost always have to be approved by the customer before they can be acted upon. Correctly identifying the customer needs can avoid a condition known as 'design creep' which occurs in the absence of realistic initial expectations, and later by failing to communicate fully with the client during the design process. It can be defined in terms of its results; "at one extreme is a circuit with more functionality than necessary, and at the other is a circuit having an incorrect functionality".〔DeMers, 1997〕 Nevertheless some changes can be expected and it is good practice to keep options open for as long as possible because it's easier to remove spare elements from the circuit later on than it is to put them in. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「circuit design」の詳細全文を読む スポンサード リンク
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