Circuit and system design
Under circuit and system design is the systematic analysis of a complete circuit function, a partitioning of the overall circuit function into individual sub-circuit functions, the implementation of the sub-circuit functions by electronic components, the realization of the overall circuit function and the subsequent testing of the total switching function. The switching function can be a purely digital, a purely analog or a mixed analog-digital circuit.
Definition of the overall circuit function
The switching function to be implemented is (mostly) described in text form by the client. This description must be so comprehensive that the circuit designer can use the description to implement the complete circuit function. The circuit developer and the client then coordinate the description and, if necessary, add content or further detail the description.
The more circuit developers work on the overall circuit, the more precise the definition must be. For example, electrical developers, software developers, mechanical developers, circuit board detachers and test developers can be involved in the overall project.
Systematic design method
The top-down method is usually used in the subsequent circuit and system design of hardware logic circuits, programs and the logic functions of programmable components .
This includes, for example, the development of the logic function of microprocessors , of application-specific integrated circuits (ASICs) and of logic functions with discrete logic components. Furthermore, programmable logic components such as Field Programmable Gate Arrays (FPGAs) or Programmable Logic Devices (PLDs) can be developed using this design method.
Other design methods have mostly proven to be of little use in practice. Likewise, an unstructured approach has mostly turned out to be ineffective.
Input and output behavior of the overall circuit function
In the next step the input and output behavior of the complete circuit is specified. For this purpose, all input signals and the respective level definitions are described. In the case of purely digital circuit parts , these can be, for example, logic levels of digital logic components such as TTL , CMOS or ECL logic levels. These can also be mains voltages (for example alternating voltages with a voltage level of 230 V) or direct voltages (for example 24 V).
Specification of the partial circuit functions
Then the complete circuit function is broken down into individual sub-circuit blocks. This also includes partial circuit functions at the input and output of the overall circuit for signal level adjustment and for supplying voltage to the overall circuit . This partial circuit function can, for example, adapt the logic level at the input and output of the overall circuit with the internal logic function (e.g. logic components, microprocessors, ...). The connection signals between the individual sub-circuit blocks are then specified as internal connection lines.
Realization of the partial circuit functions
Implementation of the individual switching functions only begins when all the individual partial circuit functions have been specified. For this purpose, the required electronic components are selected and combined into circuit functions.
This can include the following functions:
- Development of the logic function of programmable logic components (PLDs, FPGAs and ASICs)
- Programming of microprocessors, microcontrollers or digital signal processors
- Power supply
- Analog circuit functions
- Digital circuit functions
- Input and output interfaces
- PCB unbundling
- Electromechanical circuit elements
- Mechanical construction elements
- Cooling
For test purposes , these partial circuit functions can be set up and tested as a sample circuit.
Realization of the overall circuit function
The overall circuit is formed from the individual partial circuit functions. Here, the complete circuit is completely set up as a sample or pre-series circuit. The complete circuit function is built on a printed circuit board and built into the housing.
Test of the overall circuit function
The complete circuit is tested for correct function after implementation. Among other things, all points of the customer's circuit specification are tested. Furthermore, the relevant protection and safety functions, the relevant standards and regulations are taken into account in the tests .
Release of the overall circuit function
Only after the successful test of the entire circuit is it released and handed over to the user.