PCB and Circuit Design
Designing something is considered an art that not only requires essential skills but also creativity. The more creativity, the more interesting and attractive the end product is. The word ‘design’ is mostly associated with architecture or textile but circuit design is also something that is getting as much attention as the former two subjects. Just like architecture or the textile industry, the electronics industry is becoming very prevalent in the modern era where everything is predominantly related to electric circuits. Every possible field is being revolutionized by small electronic components that not only efficiently perform specific tasks but are also very inexpensive and easy to use.
Circuit design is usually done to implement practical electronic hardware to perform a specific task. Software can easily predict the working of a particular circuit which can be then designed physically using components such as Integrated Circuits (ICs), resistors, capacitors, etc.
PCB and Circuit Design Procedure:
Circuit Design procedure is a simple straightforward process that if followed correctly results in a fully functional prototype. The whole procedure can be broken down into simple steps. These are as follows:
- Theoretical Modelling
Circuit designing starts with writing down the main idea/purpose of your circuit. This step involves developing a basic block diagram where the input and outputs of the circuit-to-be-developed are identified along with the functionality that is expected from the circuit. To better understand, an example will be used to explain the whole design process. Let us suppose that we need to design a simple circuit that turns on a buzzer each time a button is pressed. For this, we will identify the inputs and outputs of the circuit. The input will be a push-button that will input a logic level based on its state. The output will be the sound generated by the buzzer. The buzzer will be turned on whenever the switch is pressed.
- Component Selection
Once a theoretical model is developed, suitable electronic components are selected. The components are chosen based on the circuit parameters such as max input voltage/current, maximum power consumption, circuit size, etc. Based on these parameters, components are chosen. Each component has a datasheet that fully describes the power ratings of that particular component. For our example, we will use a 5W buzzer that is compatible with 5V/1A source. For switching we will select a MOSFET that is able to conduct 1A current. Moreover, we will also select connectors for feeding power to the circuit and the buzzer.
- Schematics Development
The most important step of the circuit design procedure is the schematics development. Schematics development is basically designing an accurate circuit diagram that shows the symbols of each electrical component and the wires connecting them to form a circuit. The schematics is the most defining and crucial part of any circuit design because it dictates the interconnection of each component involved. Any mistake in this step will result in an incorrect final design.
- PCB Layout
After completing schematics development, the next step involves the designing of the PCB (Printed Circuit Board). PCB is designed according to the physical dimensions required by the user. PCB is basically a board containing copper traces connecting different components. PCB is the main product on which components are soldered to form the final product.
- Fabrication and Assembly
Once the PCB layout is complete, the fabrication files are generated. These fabrication files are sent to a fabrication facility where PCBs are manufactured. Before sending files for manufacturing, these files are carefully checked for potential errors.
After fabrication, the components are soldered properly and the manufacturing process concludes. Proper soldering has to be ensured so that the final circuit functions as desired.
- Testing and Debugging
After the prototype has been developed, the testing and debugging process starts. The circuit is checked properly to avoid any accidents or damages. If there is a problem, the circuit is debugged using proper test equipment. If required, the circuit is redesigned to rectify the problem.
In case of successful testing, the final product is cleared for the end-user to use.
CAD software for Circuit Design
With the increasing demand for electronic circuit development, more sophisticated and user-friendly software is required. Today there are many software present to develop circuit boards with ease and confidence. Some of them are worth mentioning
- KiCad
KiCad is a software suite for designing and simulating electric circuits. It’s a free and open-source platform which makes it the first choice for many developers around the world.
- Altium
Altium is the premiere PCB design software that belongs to a multi-national Australian-American company. This software comes with an annual subscription and is a very sophisticated tool used by many industry professionals.
- EAGLE
Easily Applicable Graphical Layout Editor (EAGLE) developed by CadSoft Computer GmbH is one of the oldest PCB design software. It is also used by many industry professionals.
- OrCAD
Developed by CADENCE systems, OrCAD is a classic PCB design software for Windows released in 1985. One of the oldest software available comes with a user-friendly graphical interface and a big community for support.
To conclude this section, many reputed software are available for circuit design. Each of them has industry-proven tools and the selection of a particular software is entirely the preference of the user.
Design Process Cycle
The circuit design process is usually a time-consuming process that requires careful attention. A small mistake can cost a lot of money, so it is always suggested to carefully design circuits. Complex circuit boards like PC-Motherboards, RAMs, etc. can take up to more than a year to be designed. Usually, the fabrication and assembly don’t take much time since these processes are fully automated nowadays. PCB layout takes the most time which includes component placement, routing, and aesthetics.
Types of Circuit Design
Based on the different types of electrical technology available, the circuit design has been divided into different types. These are as follows:
High-Speed Digital Design
Such designs use high-speed circuits that use very fast pulses to process data. Such circuits are very difficult to design because of the nature of signals present on board. High-speed signals induce noise which can disturb the normal functioning of the circuit.
RF/ Microwave Design
As the name suggests, such design include high-frequency signals, which require very low loss medium and proper impedance tracks to function properly. Appropriate design rules are required to be followed in the design process of such circuits.
Simple DC to Low-Frequency Design
Most simple kinds of circuits to design. These include normal designs like motor control circuitry, power supplies, simple logic circuits, etc. No special rules are required for such designs and just involve simple routing.