With the development of PCB design and the rapid increase in frequency, the challenges of high-frequency PCBs have become more pronounced. These challenges include miniaturization and cost reduction.

Interference issues have grown increasingly complex. Current research identifies four main types of interference: voltage noise, transmission line interference, coupling, and electromagnetic interference. This paper analyzes various interference problems in high-frequency circuit boards and proposes practical solutions.

In high-frequency PCB circuits, power supply noise is particularly critical for signal integrity. Thus, minimizing power supply noise is paramount. A clean ground is as crucial as clean power because power supplies inherently possess impedance, which can introduce noise.

To mitigate this, efforts should focus on minimizing power supply impedance. Utilizing dedicated power and ground planes is highly effective. Hierarchical power supply design, superior to bus designs in most cases, ensures minimal impedance paths, thereby reducing noise. Moreover, the power plane must accommodate signal loops to minimize noise—an aspect often overlooked in low-frequency circuits.

Attention must also be given to through-holes on the board. Through-holes on power layers should be strategically placed to avoid signal loop interference. Oversized power layers can force signals to detour, increasing loop area and noise. Concentrated signal lines near openings can exacerbate crosstalk due to shared impedance.

Effective grounding of cables is crucial. Each signal should have its own dedicated signal loop to minimize loop area, ensuring minimal interference.

Separate placement of analog and digital power supplies is recommended. High-frequency devices are sensitive to digital noise, necessitating separate placement and careful connection at the power inlet. Signal crossings between analog and digital domains should incorporate rings to minimize loop area and noise.

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This revision aims to enhance clarity and flow while maintaining the technical accuracy and specificity of the original content.

Power line coupling: When AC or DC power lines are subjected to electromagnetic interference, they transmit this interference to other devices. To eliminate crosstalk in PCB design, several approaches are effective. The magnitude of crosstalk increases with higher load impedance, so signal lines sensitive to interference from crosstalk must be routed carefully.

Capacitive crosstalk can be reduced by maximizing the distance between signal lines. Ground plane management and spatial separation of traces (such as isolating active signal lines from ground traces, especially those with state changes, and increasing ground clearance) help reduce inductive effects.

Inserting ground traces between adjacent signal lines effectively reduces capacitive crosstalk; ideally, these traces should enter the ground plane at intervals of every 1/4 wavelength.

To minimize induced crosstalk, minimize and eliminate loop areas where possible. Avoid signal-sharing loops and focus on ensuring signal integrity through proper termination techniques during soldering.

Designers can improve signal integrity by optimizing the microstrip lengths of shielding copper foils. For systems employing dense connectors, a unified PCB design for termination is recommended.

As speeds increase, EMI issues become more pronounced across various aspects, particularly affecting high-speed devices sensitive to high-frequency PCB error signals. Conversely, low-speed devices are less affected by such errors.

Several methods mitigate electromagnetic interference in PCB design:

– Reduce loops: Each loop acts as an antenna, so minimize their number, area, and antenna effects. Ensure each signal path has only one loop at any given point, avoid unnecessary loops, and maximize use of power planes.

– Filtering: Employ filtering on both power and signal lines to attenuate EMI. Methods include decoupling capacitors, EMI filters, and magnetic components. Refer to figure for EMI filter configurations.

Given the length constraints and numerous shielding articles available, we won’t detail methods for reducing high-frequency equipment speeds. Increasing the PCB board’s dielectric constant can prevent high-frequency signals from radiating outward near transmission lines.

Thicker PCB boards and minimized microstrip line thickness prevent electromagnetic radiation overflow. In summary, high-frequency PCB design should adhere to principles of unified and stable power supply and ground, meticulous wiring, proper termination to eliminate reflections, and careful cable routing to minimize capacitive and inductive crosstalk and meet noise suppression requirements.