Design Considerations

a. Track Width and Spacing: To ensure optimal signal integrity, it is crucial to maintain a proper track width and spacing. Wider tracks reduce crosstalk and parasitic capacitance, while narrower tracks may lead to signal degradation. It is recommended to use track widths and spacing as per the IPC standards for the specific application.

b. Layering and Stackup: The layering and stackup of the PCB play a vital role in achieving optimal signal integrity. It is advisable to use a multi-layer stackup with appropriate ground and power planes to minimize noise and ensure a stable signal transmission.

c. Routing: Proper routing techniques are essential to minimize crosstalk and signal interference. Avoid routing high-speed signals parallel to each other or near power lines. Use controlled impedance routing and maintain a consistent impedance throughout the signal path.

d. Shielding: To protect high-speed signals from external interference, it is recommended to use shielding techniques such as conductive coatings or enclosures. Shielding helps in reducing crosstalk and ensuring a cleaner signal transmission.

Material Selection

a. Base Material: Choose a high-quality base material with good electrical properties for the aluminum PCB. FR-4 or higher grade materials are preferred for high-speed signal applications.

b. Conductive Material: Select a conductive material with low resistance and suitable for the intended application. Aluminum is a popular choice due to its excellent thermal conductivity, but it may have higher resistance compared to copper. Consider using copper or gold plating for high-speed signal applications to ensure better conductivity.

Fabrication and Assembly

a. Drilling and Routing: Accurate drilling and routing are crucial for achieving optimal signal integrity. Use high-precision equipment to maintain tight tolerances and minimize signal degradation.

b. Plating: Proper plating of the conductive paths is essential to ensure good electrical connectivity. Choose the appropriate plating method, such as immersion gold or organic solderability preservative (OSP), based on the application requirements.

c. Component Placement: Carefully place components to minimize signal interference and crosstalk. Maintain adequate spacing between high-speed components and avoid placing them close to power lines or other high-speed signals.

d. Soldering: Use high-quality soldering techniques and materials to ensure proper electrical connections. Consider using surface mount technology (SMT) or through-hole components, depending on the application requirements.

Testing and Validation

a. DC Parameters: Measure and validate the DC parameters of the aluminum PCB, such as resistance, capacitance, and inductance, to ensure they meet the design specifications.

b. AC Parameters: Perform AC parameter testing, such as high-frequency signal analysis, to assess the signal integrity of the PCB. Use suitable test equipment and analyze the signal response, including impedance, phase, and delay.

c. Crosstalk and Interference Testing: Evaluate the crosstalk and interference levels between different signal paths on the PCB. Use appropriate test methods, such as crosstalk testing between adjacent traces or slots.

Achieving optimal signal integrity in aluminum PCB assembly requires careful consideration of design, material selection, fabrication, and testing. By following the tips and best practices discussed in this article, engineers can ensure reliable and high-quality signal transmission in aluminum PCB-based applications.

Rigid-flex PCBs enhance reliability by improving signal integrity and reducing noise in electronic devices. These factors are critical in ensuring consistent and accurate signal transmission, especially in high-speed and high-frequency applications.

The integrated and flexible sections in rigid-flex PCBs minimize signal loss and impedance mismatches. With fewer interconnects and shorter signal paths, the potential for signal degradation is significantly reduced. This results in improved signal quality, reduced distortion, and enhanced system performance.

Additionally, rigid-flex PCBs offer excellent electromagnetic compatibility (EMC) characteristics. Combining rigid and flexible materials helps reduce electromagnetic interference (EMI) by providing shielding and isolation between sensitive circuitry and external electromagnetic sources. This further contributes to the reliable and noise-free operation of electronic devices.

Increased Design Flexibility and Reduced Interconnect Complexity

Rigid-flex PCBs enhance reliability through increased design flexibility and reduced interconnect complexity. These factors simplify the PCB layout and assembly process, minimizing the potential for errors and improving the overall reliability of the electronic device.

The flexibility of rigid-flex PCBs allows for innovative and optimized designs. It enables the placement of components in unconventional positions and the creation of complex three-dimensional layouts. By eliminating the need for connectors and reducing the number of interconnects, the potential points of failure are reduced, resulting in improved reliability.

Moreover, the streamlined design of rigid-flex PCBs reduces the complexity of interconnects. This simplification reduces the chances of wiring errors, loose connections, solder joint fatigue, and familiar sources of failure in traditional PCB designs. The reduced interconnect complexity enhances the overall reliability of the PCB and minimizes the risk of electrical discontinuities.

Enhanced Thermal Management Capabilities

Rigid-flex PCBs contribute to enhanced reliability by providing superior thermal management capabilities. Efficient heat dissipation is crucial for maintaining the optimal operating temperature of electronic components, as excessive heat can lead to premature failure or performance degradation.

Combining rigid and flexible materials in rigid-flex PCBs allows for integrating thermal vias, heat sinks, and other thermal management techniques. These features help efficiently conduct and dissipate heat away from sensitive components, ensuring their longevity and reliable operation.

Furthermore, rigid-flex PCBs enable better heat distribution throughout the PCB, preventing localized hotspots. This promotes uniform temperature distribution, reducing the thermal stress on components and solder joints. By effectively managing heat, rigid-flex PCBs enhance electronic devices’ overall reliability and durability.

Rigid-flex PCBs enhance reliability through improved signal integrity, reduced noise, increased design flexibility, reduced interconnect complexity, and enhanced thermal management capabilities. These factors ensure consistent and accurate signal transmission, simplify the PCB layout and assembly process, and effectively manage heat. When seeking rigid-flex PCBs, collaborating with a reliable supplier offering wholesale options ensures access to high-quality and reliable solutions for electronic devices.

Rigid-flex PCBs offer enhanced durability through their mechanical strength and resistance to environmental factors. These attributes contribute to the longevity and reliability of electronic devices in various applications.

Combining rigid and flexible materials in rigid-flex PCBs provides robust mechanical strength. The frozen sections offer structural support and protect sensitive components from external forces. This structural integrity allows the PCB to withstand bending, folding, and twisting without compromising its electrical connections. As a result, electronic devices incorporating rigid-flex PCBs are better equipped to endure physical and repetitive movements.

Furthermore, rigid-flex PCBs exhibit excellent resistance to environmental factors. The flexible layers, typically made of polyimide or similar materials, offer thermal stability and electrical insulation properties. This enables the PCB to withstand temperature variations, moisture, and chemical exposure, making it suitable for challenging operating conditions. Electronic devices using rigid-flex PCBs can maintain their performance and reliability even in harsh environments.

Reduced Failure Points and Improved Interconnect Reliability

Rigid-flex PCBs enhance durability by reducing failure points and improving interconnect reliability. These factors minimize the risk of failures due to loose connections, solder joint fatigue, and other common issues associated with traditional PCB designs.

Unlike conventional PCBs that require connectors and cables to interconnect separate boards or sections, rigid-flex PCBs eliminate the need for additional components. Integrating multiple PCBs into a single structure significantly reduces the number of interconnects. This reduction in failure points enhances the overall reliability of the PCB and minimizes the chances of intermittent failures or electrical discontinuities.

The absence of connectors also eliminates the potential problems associated with them, such as contact resistance and mechanical wear.

This results in improved interconnect reliability, ensuring stable and uninterrupted electrical connections. Electronic devices incorporating rigid-flex PCBs benefit from enhanced durability and reduced maintenance requirements.

Enhanced Shock and Vibration Resistance

Rigid-flex PCBs excel in shock and vibration resistance, contributing to the durability of electronic devices in dynamic environments. The combined rigid and flexible construction protects against mechanical stresses encountered during transportation, operation, or physical impacts.

The rigid sections of the PCB offer structural rigidity, effectively distributing and absorbing mechanical shocks. This prevents excessive stress on the components and solder joints, reducing the risk of damage or failure. The flexible portions act as shock absorbers, further dissipating the energy generated by vibrations or impacts.

Rigid-flex PCBs mitigate the potential for component displacement, solder joint fractures, or electrical failures by effectively dampening shocks and vibrations. This ensures the long-term reliability and durability of electronic devices, even in rugged environments or applications with high levels of mechanical stress.

Rigid-flex PCBs contribute to enhanced durability through their mechanical strength, resistance to environmental factors, reduced failure points, improved interconnect reliability, and enhanced shock and vibration resistance. These qualities make them a reliable choice for electronic devices in various applications. When seeking rigid-flex PCBs, consider partnering with a reputable supplier offering wholesale options to ensure access to high-quality, durable solutions.

A rigid-flex PCB typically consists of alternating layers of rigid and flexible substrates laminated using advanced manufacturing techniques. The frozen sections provide structural support and house components, while the flexible cells enable bending and folding without damaging the PCB.

The flexible portions of a rigid-flex PCB are typically made of polyimide or similar materials, known for their excellent flexibility, thermal stability, and electrical insulation properties. These flexible layers can be single-sided or double-sided, accommodating the placement of traces and components on both sides.

Rigid-flex PCBs are highly customizable, allowing for complex three-dimensional designs. They can be manufactured in various shapes, including L-shaped, Z-shaped, or even curved configurations, providing designers with unprecedented flexibility and space optimization opportunities.

Advantages of Rigid-flex PCBs over Traditional PCBs

Rigid-flex PCBs offer several advantages over traditional rigid or flexible PCBs, making them a preferred choice for many advanced electronic applications. Some key benefits include:

1. Space Savings: Rigid-flex PCBs enable the integration of multiple PCBs into a single structure, reducing the overall size and weight of the electronic device. Eliminating the need for connectors and cables between separate PCBs saves valuable space, allowing for more compact and streamlined designs.

2. Reliability and Durability: Combining rigid and flexible materials in rigid-flex PCBs enhances their durability and reliability. The risk of failures due to loose connections, solder joint fatigue, or mechanical stress is minimized by eliminating the need for connectors and reducing the number of interconnects. This results in more robust and long-lasting electronic devices.

3. Improved Signal Integrity: Rigid-flex PCBs offer better signal integrity than traditional PCBs. The potential for signal loss, reflections, and electromagnetic interference (EMI) is significantly reduced with fewer interconnects and impedance mismatches. This ensures reliable and consistent signal transmission, especially in high-speed and high-frequency applications.

4. Design Flexibility: Rigid-flex PCBs provide greater design flexibility, allowing for the creation of innovative and intricate layouts. The ability to bend and fold the PCB enables the placement of components in unconventional positions, optimizing available space. This flexibility also simplifies the design of complex circuits by reducing the need for additional connectors and cabling.

5. Cost and Assembly Efficiency: While rigid-flex PCBs may have a higher initial manufacturing cost than traditional PCBs, they often result in overall cost savings. Integrating multiple PCBs into a single structure eliminates the need for additional connectors, cables, and assembly processes. This reduces assembly time, labour costs, and overall manufacturing efficiency.

Rigid-flex PCBs offer distinct advantages over traditional rigid or flexible PCBs. Their unique construction combining rigid and flexible materials allows space savings, improved reliability, enhanced signal integrity, greater design flexibility, and cost efficiency. Choosing a reliable rigid-flex PCB supplier for wholesale rigid-flex PCBs ensures access to high-quality and customizable solutions for advanced electronic applications.

Durability refers to the ability of a device to withstand physical stress, such as bending, twisting, and vibration, without compromising its functionality. On the other hand, reliability relates to the device’s ability to consistently perform its intended functions over an extended period without failures or malfunctions. Durable and reliable are critical for ensuring user satisfaction and minimizing costly repairs or replacements.

Introducing Rigid-flex PCB Technology

Rigid-flex PCBs are printed circuit boards that combine rigid and flexible materials into a single panel. This unique construction allows for rigid and flexible areas within the identical PCB, enabling greater design flexibility and functionality. Rigid-flex PCBs offer several advantages over traditional rigid or flexible PCBs, making them an ideal choice for applications where durability and reliability are paramount.

One of the critical benefits of Rigid-flex PCBs is their ability to withstand mechanical stress. Combining rigid and flexible layers provides structural integrity, allowing the PCB to endure bending and twisting without compromising its electrical connections. This feature is precious in electronic devices subject to frequent handling or mechanical stresses.

Furthermore, Rigid-flex PCBs reduce the number of interconnect points compared to traditional PCB designs. With fewer interconnects, the chances of failure due to loose connections or solder joint fatigue are significantly reduced. This improves the overall reliability of the PCB and reduces the risk of intermittent failures or electrical discontinuities.

Rigid-flex PCBs offer several features and characteristics that enhance electronic device durability and reliability. These include:

1. Mechanical Strength: The combination of rigid and flexible materials in Rigid-flex PCBs provides excellent mechanical strength, allowing them to withstand bending, folding, and vibration without compromising functionality. This makes them ideal for applications where the PCB is exposed to physical stress or repetitive movements.

2. Environmental Resistance: Rigid-flex PCBs can be designed to have superior resistance to environmental factors such as moisture, temperature variations, and chemical exposure. This ensures the PCB’s longevity and reliability even in harsh operating conditions.

3. Reduced Failure Points: Rigid-flex PCBs eliminate the need for connectors and solder joints, familiar sources of failure in traditional PCB designs. By reducing the number of failure points, the overall reliability of the PCB is improved, resulting in a more durable electronic device.

4. Improved Signal Integrity: The integrated rigid and flexible sections in Rigid-flex PCBs help minimize signal loss, impedance mismatches, and electromagnetic interference (EMI). This leads to improved signal integrity, ensuring electronic devices’ reliable and consistent performance.

Rigid-flex PCB technology offers significant advantages in enhancing the durability and reliability of electronic devices. Combining rigid and flexible materials, their unique construction allows for improved mechanical strength, reduced failure points, and enhanced signal integrity. By choosing a reliable rigid-flex PCB supplier, electronic device manufacturers can ensure the long-lasting performance of their products.

There are a huge range of PCB board materials that can meet your performance requirements. Quality PCB board materials don’t only offer great functionality, but also have great durability. In addition, proper material selection is good way to start your PCB manufacturing and PCB assembly. Also, there are parameters and factors that determine the type of material to use for your PCB project.

This comprehensive guide will help you discover the most common types of printed circuit board materials.

What are PCB boards made of?

Selecting a board material requires considering certain things. PCBs comprise some crucial layers. What are circuit boards really made of?

Substrate layer

The substate layer is the foundation of the printed circuit board. It is usually manufactured from fiberglass. Fiberglass is a very rigid materials, hence, it offers PCB rigidity. However, there are other materials used for substrate. This includes epoxies, CEM-1, G-11, insulated metal substrate, FR-1, and polyimide. Substrates are specially made to meet some requirements like dielectric constant and glass transition temperature. Fiberglass, which is popularly known as FR-4, is the most commonly used material for substrates.

Conductive layer

The copper layer is the conductive layer that makes signal traces. These signal traces conduct electricity in the circuit. Also, copper is a common material used for the conductive layer of a printed circuit board. Other materials like gold and silver can also be used. However, the conductive layers of PCBs are mostly made of copper. This is because copper is a good conductor of electricity.

Solder mask layer

Solder mask comprises a thin layer of polymer. It is on top of the copper clad laminate. Also, the solder mask gives the printed circuit board the green color. This layer prevents the formation of solder bridges by helping PCB manufacturers to solder the appropriate areas on the PCB board. Also, the solder mask prevents conductive copper traces from having contact with metal, solder, and other conductive materials.

Silkscreen layer

Silkscreen is an epoxy ink usually printed on the board. Also, it is a reference designator that indicates where to place components on the circuit board. Furthermore, it helps in detecting some warning symbols. A silkscreen helps to detect manufacturer marks and test points. Also, silkscreen is mostly white in color.

Types of PCB Substrate Materials

FR-4

FR4 is the most commonly used PCB substrate material. It is an epoxy resin laminate sheet reinforced with glass. Also, the epoxy of this material is flame retardant and water resistant. The “FR-4” simply means flame retardant level 4. Also, FR-4 has a high tensile strength and glass transition temperature. Therefore, this substrate can reach about 1180oC. Furthermore, this material is ideal for rigid PCBs.

FR-2

This substrate material has the lowest performance. FR-2 means flame retardant level 2. It comprises phenolic material. Also, FR-2 is commonly used in simple consumer electronics like small low cost radios.

FR-1

FR-1 is ideal for single-sided PCBs. It is a flame retardant level 1 material which is paper-based. It is similar to FR-2 as they both have identical properties. However, FR-1 features a higher temperature value.

Teflon (PTFE)

Teflon is an extremely flexible material that provides no resistance and as such, it is ideal for high speed signals. Also, Teflon is a type of plastic that features high mechanical strength, high degree of insulation, and flame resistance.

Flexible substrates

Flexible substrates can foldable and bendable materials that can form desired shapes. Also, these substrates enable designers to create circuit boards that can fit into the smallest enclosures. Rather than using epoxy resin or fiberglass, flexible substrates integrate plastic films.

These substrates are usually made with materials like liquid crystal polymer (LCP), polyimide, and polyester. In addition, polyimide is the most common material used for flexible substrates.

Metal substrates

Metal substrates are commonly made of aluminum. They offer great thermal and high dielectric properties. Also, aluminum can withstand temperatures of 350 degrees Celsius. These substrates provide exceptional high frequency performance. Therefore, it is ideal for applications like wireless communication base stations, RF sector, and LED lighting.

Other PCB Substrate Material Types

Asides from the materials mentioned above, there are other types of PCB substrate materials.

Fine ceramic

Examples of fine ceramic substances include aluminum nitride and aluminum oxide. Fine ceramic features great endurance when used in environments with high temperature. Also, ceramic compounds feature low CTE, high decomposition temperature, and high glass transition temperature.

CEM1

The composite epoxy material 1 (CEM1) has a whitish color and is usually integrated in printed circuit boards with a conductive layer. CEM1 is a material sandwiched between phenol substances and a glass fiber epoxy layer. Also, CEM1 features similar dielectric properties with FR-4. However, this material is cheaper than FR-4.

LTCC

Low temperature co-fired ceramics (LTCC) is commonly used for multilayer PCB manufacturing. Also, this circuit board material comprises burnt aluminum oxide. It is possible to burn LTCC substrates at temperatures of about 900oC by simply adding glass materials to aluminum oxide. Also, LTCC substrates are ideal for high frequency RF modules.

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High Speed Digital Design Basics

So what is high speed board design? High speed design specifically refers to systems that use high speed digital signals to pass data between components. The dividing line between a high speed digital design and a simple circuit board with slower digital protocols is blurry. The general metric used to denote a particular system as “high speed” is the edge rate (or rise time) of digital signals used in the system. Most digital designs use both high speed (fast edge rate) and low speed (slow edge rate) digital protocols. In today’s era of embedded computing and IoT, most high speed circuit boards have an RF front end for wireless communication and networking. Although all designs begin from a schematic, a major part of high speed PCB design is focused in interconnect design, PCB stackup design, and routing.

Planning Your High Speed PCB Stackup and Impedance

The PCB stackup you create for a high speed circuit board will determine the impedance, as well as ease of routing. All PCB stackups include a set of layers dedicated to high speed signal, power, and ground planes, and there are several points to consider when assigning layers in a stackup:

Board size and net count: How large will the board be and how many nets do you need to route in the PCB layout. Physically larger boards might have enough space to allow you to route throughout the PCB layout without using more than a few signal layers.

Routing density: In the case where net counts are high and the board size is constrained to a small region, you may not have a lot of room for routing around the surface layer. Therefore, you’ll need more internal signal layers when traces are pushed closer together. Going to a smaller board size can force higher routing density.

Number of interfaces: Sometimes it’s a good strategy to route only one or two interfaces per layer, depending on the width of the bus (series vs. parallel) and the board size. Keeping all signals in a high speed digital interface on the same layer ensures consistent impedance and skew is seen by all signals.

Low speed and RF signals: Will there be any low speed digital or RF signals in your digital design? If so, these may take up space on the surface layer that could be used for a high speed bus or components, and an additional internal layer might be required.

Power integrity: One of the cornerstones of power integrity is the use of a large power plane and ground plane for each voltage level required in your large ICs. These should be placed on adjacent layers to help ensure there is high plane capacitance to support stable power with decoupling capacitors.

PCB Material Options, Layer Count, and Thickness

Before designing your PCB stackup, consider the layer count needed to accommodate all digital signals in your design. There are several ways to determine this, but these methods rely on a bit of math and some past experience in high speed board design. In addition to the points listed above for considering layer count, large high speed ICs with BGA/LGA footprints can dictate the required board size. When doing BGA fanout, you can generally fit 2 rows per signal layer, and make sure to include the power and ground plane layers in your layer count when building a stackup.

FR4-grade materials can generally be used in a high speed digital design as long as the routes between components are not too long. If routes do become too long, there will be too much loss in your high speed channel, and components on the receiver end of the channel may not be able to recover signals. The primary material property to consider when selecting materials is the loss tangent of your PCB laminates. The channel geometry will also determine losses, but generally opting for a lower loss tangent FR4 laminate is a good place to start in smaller boards.

If your routes are too long, then a more specialized material might be needed as the substrate for your high speed signals. PTFE-based laminates, spread glass laminates, or other specialized material systems are a good choice to support larger high speed digital boards, where routes are very long and low insertion loss is required. A good entry-level high-Tg set of laminate materials for small-sized high speed PCBs is 370HR. For larger boards, something like Megtron or Duroid laminates are good options.

Analysis of power supply noise

Power supply noise is noise that is generated or disturbed by the power supply itself. The interference is manifested in the following aspects:

1) Distributed noise caused by the inherent impedance of the power supply itself. In high-frequency circuits, power supply noise has a large influence on high-frequency signals. Therefore, a low noise power supply is first required. A clean ground and a clean power supply are just as important.

Ideally, the power supply is impedance-free, so there is no noise. However, in practice, the power supply has a certain impedance, and the impedance is distributed over the entire power supply, so noise is also superimposed on the power supply. Therefore, the impedance of the power supply should be reduced as much as possible. It is better to have a dedicated power plane and ground plane. In high-frequency circuit design, it is generally better to design the power supply in layers rather than in the form of a bus, so that the loop can always follow the path with the least impedance. In addition, the power board provides a signal loop for all generated and received signals on the PCB, which minimizes the signal loop and reduces noise.

2) Common mode field interference. Refers to the noise between the power supply and the ground. It is caused by the interference caused by a loop formed by the disturbed circuit and the common mode voltage caused by the common reference surface. The value depends on the relative electric field and magnetic field. Strength is weak.

On this channel, the drop in Ic causes a common-mode voltage in the series current loop, affecting the receiving portion. If the magnetic field dominates, the value of the common mode voltage generated in the series ground loop is:

ΔB in the formula (1) is the amount of change in the magnetic induction intensity, Wb/m2; S is the area, m2.
If it is an electromagnetic field, when its electric field value is known, its induced voltage is
Equation (2) is generally applicable to L=150/F or less, and F is the electromagnetic wave frequency of MHz.

If this limit is exceeded, the calculation of the maximum induced voltage can be simplified as:

3) Differential mode field interference. Refers to the interference between the power supply and the input and output power lines. In the actual PCB design, the author found that its proportion in power supply noise is very small, so it can be omitted here.

4) Interline interference. Refers to interference between power lines. When there is mutual capacitance C and mutual inductance M1-2 between two different parallel circuits, if there is voltage VC and current IC in the interference source circuit, it will appear in the interfered circuit:
a. The voltage coupled through the capacitive impedance is
In equation (4), RV is the parallel value of the near-end resistance and the far-end resistance of the interfered circuit.
b. Series resistance through inductive coupling
If there is common mode noise in the interference source, the interline interference generally appears in both common mode and differential mode.

5) Power line coupling. It refers to the phenomenon that the power line will transmit these interferences to other devices after the AC or DC power line is subjected to electromagnetic interference. This is the interference of the power supply noise indirectly on the high frequency circuit. It should be noted that the noise of the power supply is not necessarily generated by itself, or it may be the noise of the external interference induction, and then the noise is superimposed (radiated or conducted) with the noise generated by itself to interfere with other circuits or devices.

Countermeasures to eliminate power supply noise interference

In view of the different manifestations and causes of the power supply noise interference analyzed above, the conditions of the occurrence of the power supply noise can be specifically destroyed, and the interference of the power supply noise can be effectively suppressed. The solutions are:

1) Pay attention to the through holes on the board. The through holes make it necessary to etch the openings on the power supply layer to allow space for the through holes to pass. If the power layer opening is too large, it will affect the signal loop, the signal will be forced to bypass, the loop area will increase, the noise will increase, and if some signal lines are concentrated near the opening, sharing this loop, the common impedance will cause crosstalk.

2) The cable requires enough ground wire. Each signal needs its own proprietary signal loop, and the loop area of the signal and loop is as small as possible, that is, the signal is parallel to the loop.

3) Place the power supply noise filter. It can effectively suppress the noise inside the power supply and improve the anti-interference and safety of the system. And it is a two-way RF filter that not only filters out noise interference introduced from the power line (prevents interference from other devices), but also filters out the noise generated by itself (to avoid interference with other devices), and cross-mode common mode interference. Both inhibit.

4) Power isolation transformer. Separate the common-mode ground loop of the power supply loop or signal cable to effectively isolate the common-mode loop current generated at high frequencies.

5) Power regulator. Regaining a cleaner power supply can greatly reduce the power supply noise.

6) Wiring. The input and output lines of the power supply should be avoided at the edge of the dielectric board, otherwise it will easily generate radiation and interfere with other circuits or equipment.

7) The analog and digital power supplies should be separated. High frequency devices are generally very sensitive to digital noise, so the two should be separated and connected together at the entrance to the power supply. If the signal is to cross both analog and digital, a loop can be placed across the signal to reduce the loop area.

8) Avoid separate power supplies that overlap between different layers. Try to stagger it, otherwise the power supply noise is easily coupled through parasitic capacitance.

9) Isolate sensitive components. Some components, such as phase-locked loops (PLLs), are very sensitive to power supply noise and should be kept as far as possible from the power supply.

10) Place the power cord. In order to reduce the signal loop, noise reduction can be achieved by placing a power line on the side of the signal line, as shown in Figure 5.

11) In order to prevent the accumulated noise caused by the interference of the power supply noise on the circuit board and the external power supply interference, the bypass path can be grounded on the interference path (excluding the radiation), so that the noise can be bypassed to the ground to avoid Interfere with other devices and devices.

In conclusion

Power supply noise is generated directly or indirectly from the power supply and interferes with the circuit. When suppressing its influence on the circuit, a general principle should be followed, that is, on the one hand, the power supply noise should be prevented as much as possible. The influence of the circuit, on the other hand, should also minimize the influence of the outside world or the circuit on the power supply, so as not to deteriorate the noise of the power supply.