Circuit design is the foundation of electronics, and good layout directly affects the performance of PCB. With continuous updates to PCB design software, more advanced features are unlocked, with automatic layout and routing being the most noteworthy. However, when dealing with complex designs, designer intervention and optimization remain crucial, and complete reliance on tools is not advisable.
Therefore, mastering design layout techniques and understanding basic rules are essential for enhancing a designer’s professional competence. TechSparks provides the 100 frequently PCB design Q&A here to facilitate your learning process! Let’s get started!
Question 1: What are the key considerations for routing high-speed signals?
Question 2: How to avoid the impact of vias on PCB performance?
Question 3: Is it better to have more decoupling capacitors?
The significance of decoupling capacitors is to provide power stability and reduce power noise. However, it's clear that more isn't necessarily better. The quantity should be determined based on specific circuit requirements and design principles. For example:
- Each integrated circuit should have at least one decoupling capacitor；
- Large ICs or high-frequency circuits may require more decoupling capacitors；
- If multiple decoupling capacitors are needed, they should be distributed logically in different areas rather than just near the power pins；
Question 4: What are the standards for a high-quality PCB board?
Question 5: Should ASIC be ground-isolated in high-speed signal chain applications?
Question 6: What is the purpose of serpentining traces?
Question 7: How to mitigate EMC/EMI issues?
Question 8: What are the considerations for transmission line design in RF broadband circuits?
- Choose appropriate PCB substrate to avoid adverse effects on signal transmission characteristics, such as dielectric constant, loss tangent, and conductivity.
- Develop accurate transmission line models to predict signal behavior.
- Consider the impact of component parameters on circuit performance.
- Account for factors like bandwidth, cutoff frequency, and filtering characteristics.
- Ensure that the matching network between the transmission lines and components is effective.
Question 9: How to choose the package type for components like resistors and capacitors?
Question 10: What is the priority for signal lines and ground lines in double-sided PCB design?
Question 11: What should be considered when designing a multi-layer PCB?
Question 12: Should the design be based on the CPU frequency or the data interaction frequency of external components?
Question 13: How to determine whether noise is caused by an operational amplifier device or wiring defects?
In most cases, distinguishing whether noise is caused by the operational amplifier device itself or wiring defects can be a challenging task. Here are some common methods and considerations:
- Use an oscilloscope or spectrum analyzer to observe the spectral characteristics of the signal and noise.
- Check for voltage fluctuations and ripple on the power supply lines.
- Ensure a good ground plane and minimize ground loop paths.
- If there is suspicion of operational amplifier device failure, consider replacing the device with the same model or conducting comparative tests with different device models.
Question 14: Where does the heat come from in a PCB?
Question 15: Is it necessary to have a ground plane on the outer layer in a PCB with MCU control?
Question 16: How to Handle Multiple ADC Chips on the Board?
Question 17: What are the requirements for ground design in analog and digital circuits?
Analog Circuits: Grounding should be comprehensive, with minimal loop area and impedance matching.
Digital Circuits: Low-frequency circuits have no specific requirements, while high-frequency circuits need to consider impedance matching and ground integrity.
Question 18: How to avoid vias in high-speed PCB?
Question 19: How to choose the thickness of power traces?
Question 20: Do you need to distribute digital and analog circuits to different layers of a multi-layer PCB?
Question 21: How to avoid crosstalk issues in high-speed signals?
Question 22: How to decide on the ground plane?
Question 23: Is copper cladding required in multi-layer PCB design?
Question 24: Does pairing fine-pitch components with wide traces lead to impedance mismatch issues?
Question 25: How can you remedy the situation if differential lines cannot be achieved?
Question 26: How can you prevent interference from PWM and other abrupt signals on analog signals (e.g., op-amps)?
Question 27: What should be considered when routing LVDS signals?
LVDS signals consist of a pair of differential signals, typically composed of a positive and a negative signal. To ensure proper LVDS signal routing:
- Ensure that the lengths of the signal traces are equal.
- Maintain consistent spacing between the differential pairs.
- Add appropriate termination resistors at both the LVDS signal's transmitting and receiving ends.
Question 28: What protections are needed at the input interfaces for signals and power?
Question 29: Is it advisable to use serpentine routing when size constraints are present?
Question 30: How can you layout an amplifier to suppress the introduction of ripple?
Question 31: When designing high-frequency circuits, which is preferable, lumped parameters or distributed parameters?
Question 32: How long can the wiring be for high-speed logic devices?
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