EE Fundamentals - Circuit Development

       Electrical and Electronic Engineering of circuits, integrated circuits, microprocessors, microcontrollers and electronic packaging assembly requires organizing or populating, prototyping and manufacturing Printed Circuit Boards (PCB) and Printed Circuit Board Assemblies (PCBA).  A 'Circuit' is a widely used term defined as anything from a single component to systems containing thousands of components such as the USS, space station human, environmental and work task machine system controls.  

       In circuit development or PCBA the EE must understand the technical application including state of the art research and select from literally millions of available OEM microchips and  associated electronic components and variations to organize and interconnect the circuits so that it will deliver the (input/output) power, controls functional, mechanical operation and performance, readout or display.  Circuits can be highly integrated and dedicated applications such as running a hydroelectric power plant or as simple as adding a circuit breaker to a power switch. The application of EE practices, symbols and schematic logic layout fundamentals including constructing embedded and integrated circuits that are product, manufacturing and user-friendly with universal design usability, with appropriate universal design and localization  qualities are part of applying the human factors, user-interface and graphical interface to products, machines and computers into the circuit development process.   See Human Factors

       Circuit development is developed using a set of standardized graphic symbols and schematic documentation system.  The ability to master the arrangement of these elements, including diodes, capacitors, inductors,  registers, voltage regulators, counters, multiplexers, connectors and interconnections. Larger components include analogue and digital power, voltage and amperage supply and regulators, microprocessors, controllers boards, digital signal processors, Field-programmable gate arrays (FPGA) and Application-specific integrated circuits (ASIC).  The ability to assemble these components with the appropriate software programming to output the desired function without blowing a fuse or circuit breaker or causing a fire, is the responsibility of the Electrical Engineer specializing in Circuit Development and PCB Design. 

       If your product requires Electronic Design or engineering circuit development, it is best to have a basic working knowledge of the general types of circuits and the advantages, disadvantages and considerations of the selected circuit hardware and software design possibilities and limitations.  This includes understanding the ambiguous user interface, language use, terminology, symbology, graphic interface learning, training, and maintenance requirements.

Types of Circuits

       The process of circuit design or printed circuit board design can cover systems ranging from complex electronic production or biomedical scientific systems to the individual transistors within an integrated circuit.  From simple analog circuits to complex mixed digital circuits the circuit design process is sometimes a straight forward, planned or structured design process, but for more complex applications, the team of Industrial Designers, Mechanical and Electrical Engineers converge to follow a systematic approach.  The product system process includes  electromechanical integration of mechanical function and circuit design -  - with the use of CAD - CAE - CAM for PCB circuit - component population and simulation software, prototyping,  low quantity and high volume manufacturing and user acceptance testing.

Analog Circuits

       Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic circuits.  Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits. Analog circuits range from a single component, to systems containing thousands of components.  Analog circuits are sometimes called linear circuits although many non-linear effects are used in analog circuits such as mixers, modulators, etc. Examples of analog circuits include a vacuum tube and transistor amplifiers, operational amplifiers and oscillators. Sometimes it may be difficult to differentiate between analog and digital circuits as they may have elements of both linear and non-linear operation.

Digital Circuits

       Digital circuits are electric circuits based on a number of discrete voltage levels. Digital circuits are the most common physical representation of Boolean algebra and are the basis of all digital computers. To most engineers, the terms "digital circuit", "digital system" and "logic" are interchangeable in the context of digital circuits. In most cases the number of different states of a node is two, represented by two voltage levels labeled "Low" and "High". Often "Low" will be near zero volts and "High" will be at a higher level depending on the supply voltage in use. Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits. Digital Signal Processors are another example.  Building-blocks:

• Logic gates
• Adders
• Binary Multipliers
• Flip-Flops
• Counters
• Registers
• Multiplexers
• Schmitt triggers

Highly integrated devices:

• Microprocessors
• Microcontrollers
• Application-specific integrated circuit (ASIC)
• Digital signal processor (DSP)
• Field-programmable gate array (FPGA)
   

Mixed-signal circuits

       Mixed-signal circuits refers to integrated circuits (ICs) which have both analog circuits and digital circuits combined on a single semiconductor die or on the same circuit board.  Some analog circuitry may use digital or even microprocessor techniques to improve upon the basic performance of the circuit referring to a "mixed signal" circuit.   Mixed circuits are  increasingly common, usually applied to control an analog device using digital logic, for example the speed of a motor.  Analog to digital converters and digital to analog converters are the primary examples. Other examples are transmission gates and buffers.  Read on more about the advantages, disadvantages and considerations of using analogue or digital circuits.

Logic Gates

       A digital circuit is often constructed from small electronic circuits called logic gates.  A logic gate is an arrangement of electrically controlled switches that represent the function of Boolean logic. The output of a logic gate is an electrical flow or voltage that can, in turn, control more logic gates.  Logic gates often use the fewest number of transistors in order to reduce their size, power consumption and cost, and increase their reliability.

Integrated Circuits  (Programmable Logic Controllers - PLC)

       Integrated circuits, or embedded circuits or chips are usually programmed by software engineers and are the least expensive way to make logic gates in large volumes. Integrated circuits are usually designed by specialty EE engineers using electronic design automation software  Another form of digital circuit is constructed from lookup tables to perform the same functions as machines based on logic gates, which can be easily reprogrammed meaning that the Designer can repair design errors without changing the arrangement of wires.  Therefore, in small volume products, programmable logic controller devices (PLC) are often the preferred solution.  They are usually designed by engineers using electronic design automation software.  When the volumes are medium to large, and the logic can be slow, or involves complex algorithms or sequences, often a small microcontroller is programmed to make an embedded system.

Embedded Software

       Digital circuits are made from analog components which calculate more slowly than low-precision analog circuits that use a similar amount of space and power.  However, the digital circuit will calculate more repeatable, because of its high noise immunity.  When high-precision is needed (for example, where 16 or more bits of precision are needed), analog circuits require much more power and area than digital equivalents. When only one digital circuit is needed, and its design is totally customized, as for a factory production line controller, the conventional solution is a programmable logic controller, or PLC. These are usually programmed by electricians, using ladder logic.