Lecture
Circuit design — a scientific and technical discipline concerned with the design, creation and debugging (synthesis and analysis) of electronic circuits and devices for various purposes.
The concept of circuit design applies to a wide range of electronic devices, from complex systems down to individual transistors within an integrated circuit. Simple tasks can well be handled by a single person without additional assistance. Solving complex problems requires a systematic approach, computer modeling and the involvement of specialized engineering teams. In any case, however, circuit design in practice occupies an intermediate position between the emergence of an idea and the production of a finished electronic circuit. Its main task is to develop the structures of electronic circuits that perform the specified functions, as well as to calculate the parameters of the elements that make them up.
Sound circuit design implies a balance between economic and technical indicators. Both a shortage of design funds and their excess can be detrimental. It is important to assess the economic efficiency of the work at every stage .
The final result of circuit design work must conform to the principles of industrial design.
Circuit design can be divided into analog, digital and mixed-signal (analog-digital) circuit design.
Once the decision to carry out circuit design work has been made, prototyping becomes important. It shortens the development time of electronic circuits by reducing gross design errors. Moreover, with relatively modest resources, a prototype makes it possible in practice to test the ideas embodied in the electronic circuit. Depending on the specifics of the design, prototyping can be applied either to the development as a whole or to its individual parts .
circuit design work is carried out in the following sequence :
Like any design work, circuit design begins with drawing up the technical specification. It sets out the list of functions that the electronic circuit being created must provide, but as a rule does not specify exactly how this is to be achieved .
The technical specification is usually a detailed description of the customer's requirements for the electronic circuit and may include various electrical parameters, such as the characteristics of input and output signals, power supplies, and power consumption. It may also specify physical parameters such as size, weight, moisture resistance, operating temperature range, dissipated heat power, vibration protection, overload resistance and the like. For the electronic circuit being created to work effectively in the future, the technical specification must include the conditions of what is known as interaction design .
Depending on its complexity, the design of an electronic circuit goes through a number of stages. The only exception is the very simplest circuits, which are created in a single step. The first stage is translating the technical specification's signal-processing requirements into a block diagram of these transformations. Here, the blocks are treated purely functionally, as a kind of “black boxes”, without detailing their physical content. This approach makes it possible to break down even a very complex task into smaller pieces and solve them either sequentially or in parallel, distributing them among different engineering groups .
Next, the functional tasks of each block are examined in detail, with attention paid to the specifics of signal processing. This stage may require practical research or mathematical modeling of the processes involved. It is possible that the work will result in a need to revise the block diagram, redistributing tasks among its blocks .
Next, a schematic diagram is developed on the basis of the block diagram. Its individual components are selected and placed on a board, after which the circuit is assembled “in hardware”, producing a breadboard model. As a rule, this stage takes quite a long time, since it requires accounting for a long list of practical constraints. These include the mutual influence of the circuit's components, their availability for procurement, the maintainability of the whole design, and the requirement that it comply with standards, among other things.
The final stage is testing the breadboard model, followed if necessary by its refinement, and the creation of a pre-production electronic circuit[10].
The pre-production electronic circuit is effectively equivalent to the finally refined breadboard model. It is created to verify, during pre-production testing, that the results obtained meet the customer's requirements. Sometimes, to debug the interaction of the circuit's elements, testing is preceded by formal verification. Following the results of pre-production testing, final changes are made to the circuit. If necessary, a new pre-production sample is created and new tests are carried out .
The results of circuit design work are documented as finished drawings, and, if necessary, as manufacturing process documentation and instructions for use
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