In electrical engineering, the process of circuit design can cover systems ranging from complex electronic systems down to the individual transistors within an integrated circuit. One person can often do the design process without needing a planned or structured design process for simple circuits. Still, teams of designers following a systematic approach with intelligently guided computer simulation are becoming increasingly common for more complex designs. 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.

Traditional circuit design usually involves several stages. Sometimes, a design specification is written after liaising with the customer. A technical proposal may be written to meet the requirements of the customer specification. The next stage involves synthesising on paper a schematic circuit diagram, an abstract electrical or electronic circuit that will meet the specifications. A calculation of the component values to meet the operating specifications under specified conditions should be made. Simulations may be performed to verify the correctness of the design.

A breadboard or other prototype version of the design for testing against specification may be built. It may involve making any alterations to the circuit to achieve compliance. A choice as to a method of construction and all the parts and materials to be used must be made. There is a presentation of component and layout information to draughtspersons and layout and mechanical engineers for prototype production. This is followed by the testing or type-testing several prototypes to ensure compliance with customer requirements. Usually, there is a signing and approval of the final manufacturing drawings, and there may be post-design services (obsolescence of components, etc.).

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 . The initial specification is 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.

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 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".^[who?] Nevertheless, some changes can be expected. 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.

The design process involves moving from the specification at the start to a plan that contains all the information needed to be physically constructed at the end; this happens typically by passing through several stages, although in the straightforward circuit, it may be done in a single step. The process usually begins with the conversion of the specification into a block diagram of the various functions that the circuit must perform, at this stage the contents of each block are not considered, only what each block must do, this is sometimes referred to as a "black box" design. This approach allows the possibly highly complex task to be broken into smaller tasks either by tackled in sequence or divided amongst members of a design team.

Each block is then considered in more detail, still at an abstract stage, but with a lot more focus on the details of the electrical functions to be provided. At this or later stages, it is common to require a large amount of research or mathematical modeling into what is and is not feasible to achieve. The results of this research may be fed back into earlier stages of the design process, for example if it turns out one of the blocks cannot be designed within the parameters set for it, it may be necessary to alter other blocks instead. At this point, it is also common to start considering both how to demonstrate that the design does meet the specifications, and how it is to be tested ( which can include self diagnostic tools ).