How to Design Electronic Circuit

Electronics surround us. From smartphones to washing machines, electronic circuits power our modern world. Learning how to design these circuits is a valuable skill. This guide comprehensively introduces electronic circuit design, perfect for beginners. It covers fundamental concepts and practical techniques.

Designing an electronic circuit requires a systematic approach to ensure functionality, reliability, and efficiency. Here’s a comprehensive guide to designing electronic circuits:

Begin by clearly outlining the purpose of the circuit and identifying key features, performance criteria, and specific requirements such as:

• Input and output signals
• Voltage, current, and power requirements
• Operating temperature and frequency ranges
• Size constraints
• Budget limitations

Create block diagrams to represent the circuit’s architecture. This helps visualize how different components and subsystems interact, allowing for a modular design approach.

A schematic serves as the map for electronic circuit design, illustrating the connections between the system’s components. A robust design begins with crafting a clear, detailed schematic.

When transitioning from a concept to a schematic, precisely understand each component’s functionality within your circuit. The schematic conveys the electrical connections and the relationship between different circuit elements, aiding in troubleshooting and understanding the overall design.

Block diagrams simplify complex systems, breaking the circuit into manageable sections. By representing each functional block, such as power management or signal processing, designers can conceptualize the structure and flow of their circuit before delving into detailed schematic creation.

Select the right design software to translate your block diagram into a full-fledged schematic. CAD tools like KiCad, Eagle, and Altium Designer streamline this process with libraries of components and intuitive drawing features. A best practice is cross-verifying each connection with your block diagram, ensuring no circuit part is overlooked.

• Start with a comprehensive list of components based on the block diagram.
• Place components on the canvas, considering the flow of current and signal paths.
• Utilise net labels and connect ports logically to maintain clarity.
• Routinely check for errors with design rule check (DRC) features.
• Keep the schematic organised with clear labels and notes for future reference.

Choose components based on the schematic design and required specifications. Consider factors such as:

• Datasheets and specifications
• Obsolescence risk
• Derating and overrating (choose parts with 1.5-2 times more ratings than required)
• Lead times and availability
• Cost

Create a Bill of Materials (BOM) that includes all necessary components and materials for the circuit.

Develop the layout of the Printed Circuit Board (PCB), considering:

• Component placement and grouping
• Trace routing
• Signal integrity
• Thermal management
• Design for manufacturability (DFM) guidelines

Provide a 3D CAD model or interactive 3D PDF to help visualise the final board layout.

Use simulation tools to predict circuit behaviour under various conditions. Perform physical testing on prototypes to confirm that the circuit performs as expected in real-world scenarios.

Build a prototype of the circuit to test and validate its functionality. Conduct thorough testing to verify that the circuit meets all specifications.

Based on the results from prototyping and testing, refine the design to address any issues or make improvements. This iterative process is crucial for optimising the circuit’s performance and reliability.

Create comprehensive documentation for your design, including:

• Detailed schematics
• PCB layout drawings
• Bill of Materials
• Design rationale and decisions
• Test results and performance data

This documentation is essential for future troubleshooting, maintenance, and potential redesigns.

Implement necessary safety measures and ensure compliance with relevant industry standards. This may include:

• ESD protection
• Reverse polarity protection
• Transient and over-voltage protection
• EMC considerations
• Regulatory compliance (e.g., FCC, CE)

• Use decoupling capacitors to stabilize power supplies and reduce noise
• Implement proper grounding techniques to prevent EMI and ground loops
• Consider using microcontrollers and mixed-signal circuits to enhance efficiency
• Utilise PWM signals to reduce power consumption in battery-operated circuits
• Design for testability to facilitate easier debugging and quality assurance

Remember that electronic circuit design is an iterative process that requires patience, attention to detail, and continuous learning. As you gain experience, you’ll develop intuition for effective design practices and problem-solving techniques. Be sure to check out our more detailed article on best practice in electronic design for more information.

Understanding electronic components is fundamental to circuit design. Here are some essential components:

• Resistors: Resistors restrict current flow and control voltage levels within a circuit. They are measured in ohms and have a schematic symbol of a zigzag line.
• Capacitors: Capacitors store electrical charge. They smooth voltage fluctuations. They are measured in farads. Their schematic symbol resembles two parallel plates.
• Inductors: Inductors store energy in magnetic fields, oppose changes in current, and are measured in henries. Their schematic symbol is a coiled wire.
• Diodes: Diodes allow current to flow in only one direction. They rectify alternating current (AC) to direct current (DC). Their schematic symbol is a triangle with a line.
• Transistors: Transistors amplify or switch electronic signals and electrical power. They are the building blocks of integrated circuits (ICs). Their schematic symbol varies depending on the type.

Testing and debugging are crucial steps. They ensure a functional and reliable circuit.

• Power Supply Check: Verify correct voltage levels and polarity at the power source. Inconsistent power delivery can lead to erratic behavior.
• Component Verification: Check each component’s value. Use a multimeter to confirm resistance, capacitance, and other relevant parameters. A faulty component can disrupt the entire circuit.
• Signal Tracing: Follow the signal path through the circuit. Measure voltage and current at various points. Identify where the signal deviates from the expected behaviour.
• Functional Testing: Test the circuit’s overall functionality to ensure it performs according to the design requirements. Verify that inputs and outputs match the specifications.

• Visual Inspection: Carefully examine the circuit for any visible defects. Look for loose connections, broken wires, or short circuits. Visual cues often provide quick solutions.
• Divide and Conquer: Isolate sections of the circuit to pinpoint the source of the problem. Test each section independently. This systematic approach narrows down the faulty area.
• Substitution: Replace suspected faulty components with known good ones. If the issue resolves, the original component was likely the culprit. This helps confirm the diagnosis.
• Review the Schematic: Double-check the circuit diagram for any design or component placement errors. An incorrect schematic can lead to functional problems.

• Multimeter: A multimeter measures voltage, current, and resistance. This tool is essential for diagnosing various circuit issues. It helps pinpoint faulty components or connections.
• Oscilloscope: An oscilloscope visualizes signal waveforms. It helps analyse signal characteristics and identify anomalies. It is particularly useful for debugging complex circuits.
• Logic Analyser: A logic analyser helps debug digital circuits. It displays the logic states of multiple signals simultaneously. This aids in understanding complex digital interactions.

PCB design is a critical stage. It impacts the final circuit’s performance and reliability. Avoiding these common mistakes will save time and frustration.

Failing to include a proper ground plane can lead to electromagnetic interference and signal noise issues. A ground plane acts as a shield and provides a low-impedance signal return path.

Not checking and adhering to proper clearance rules between conductive elements on the PCB can result in short circuits or signal interference.

Omitting or improperly placing decoupling capacitors can lead to power supply instability and poor circuit performance.

Placing components too close together can make assembly, inspection, and testing difficult. It’s important to allow adequate spacing for manufacturability.

Not including enough test points (or any at all) makes it challenging to build test jigs and perform diagnostics.

Using the same trace width for all signals regardless of their requirements or spacing traces too closely can lead to signal integrity problems and increased crosstalk.

Using vias that are too small or with insufficient annular rings can cause manufacturing and reliability issues.

Failing to consider signal integrity, especially for high-speed signals, can result in poor performance and electromagnetic compatibility problems.

Not accounting for thermal considerations in component placement and PCB layout can lead to overheating issues.

Ignoring DFM guidelines can result in increased manufacturing costs and difficulties in production.

To avoid these mistakes, it’s crucial to:

• Use proper PCB design software and tools
• Set up design constraints before starting the layout
• Conduct thorough design rule checks (DRC)
• Consider signal integrity and power distribution
• Follow best practices for component placement and routing
• Adhere to manufacturing guidelines
• Perform adequate testing and prototyping