Always discouraged by signal interference, poor heat dissipation, and messy routing when doing PCB layout? Actually, as long as you master the core techniques, you can easily handle all kinds of layout challenges! Today, we've compiled 9 super practical hybrid PCB layout methods, from component placement to bottom layer shielding, all packed with practical information and no fluff, allowing beginners to quickly get started!

I. Component Placement: Follow the "Rules" to Place Components Correctly and Avoid Detours

Incorrect component placement will render all subsequent routing useless! When laying out components, not only should you follow the signal paths in the schematic and leave enough space for traces, but you must also remember these 5 principles:

• Power supplies should be compactly clustered, with decoupling designs to ensure stable power supply;
• Decoupling capacitors should be placed close to components to shorten current loops and reduce noise;
• Connectors should be placed directly at the board edge for easy external device connection without taking up core area;
• High-frequency components should be placed strictly according to the schematic flow to avoid signal corruption;
• Processors, clock generators, large storage devices, and other "core components" should be placed in the center of the board for easy connection to surrounding circuits.

II. Analog + Digital Modules: Separate Layout, No Interference
Analog and digital signals are often at odds; sharing areas can easily lead to mutual interference, resulting in poor circuit performance! The correct approach is to completely separate the two. Key points are here:

• Place precision components (such as amplifiers and reference voltage sources) on the analog plane, and dedicate the digital plane to logic control, timing blocks, and other "high-noise components";
• ADCs (Analog-to-Digital Converters) and DACs (Digital-to-Analog Converters) handle mixed signals, so treating them as analog components is more reliable;
• High-current ADC/DAC designs must have separate analog and digital power supplies (DVDD connected to the digital section, AVCC connected to the analog section);
• Microprocessors and microcontrollers generate significant heat, so placing them in the center of the circuit board and close to connected circuit blocks will result in more efficient heat dissipation.

III. Routing: Take the Shortest and Straightest Path, Avoid These Pitfalls

After the components are in place, routing is about "building signal channels." Remember these 8 principles for smoother signal transmission:

• The shorter and straighter the signal path, the better, reducing delay and interference;
• A ground plane must be placed next to high-speed signal layers to ensure normal signal return;
• High-speed circuits must be routed strictly according to the schematic signal path and cannot be arbitrarily changed;
• Use short, straight, and wide power supply traces to reduce inductance;
• Avoid making traces and vias into "antenna shapes" to avoid additional interference;
• Keep digital and analog circuit traces isolated, without crossing or overlapping;
• Pay extra attention to grounding traces connecting digital and analog zones;
• Avoid unnecessary detours and vias throughout the process, simplifying the path while reducing signal loss.

IV. Power Supply Module: Proximity Power Supply + Isolation Design – Stability is Key

The power supply is the "heart" of the circuit; improper layout can easily lead to overall failure. There are two key points:

• The power supply module must be close to the power supply components while being isolated from other circuits to prevent noise propagation;
• For complex devices with multiple power supply pins, use dedicated power supply modules for both analog and digital sections to completely eliminate digital noise interference with analog signals;
• Power lines should follow the "short, straight, wide" principle to reduce inductance and current limitations, resulting in more stable power supply.

V. Decoupling Design: Creating a Low-Noise Environment for Maximizing Device Performance

The core of decoupling is "filtering power supply noise." Power Supply Rejection Ratio (PSRR) directly determines device performance. These 5 practical methods are essential:

• **Combining Capacitors: Low-inductance ceramic capacitors filter high-frequency noise, electrolytic capacitors act as "charge reservoirs" to filter low-frequency noise, and ferrite beads can be selected to enhance isolation;
• **Place decoupling capacitors close to the device's power supply pins, and connect them to a low-impedance ground plane using short traces or vias to reduce series inductance;
• **Place small capacitors (0.01μF-0.1μF) next to the power supply pins to prevent device instability when multiple outputs switch simultaneously;
• **Keep electrolytic capacitors (10μF-100μF) no more than 1 inch away from the power supply pins; too much distance will affect filtering performance;
• **Decoupling capacitors can be connected to the ground plane in a T-shape via next to the device's GND pin, simplifying the process without additional wiring.

VI. PCB Layering: Plan Layers in Advance and Optimize Return Paths

Determine the layering scheme before routing, otherwise it will affect the signal return path. Different layer numbers require different design considerations:

• High-performance data acquisition systems should prioritize 4-layer or higher PCBs; double-layer boards are suitable for simple circuits.
• Typical 4-layer board layout: Top layer (digital/analog signals), second layer (ground layer, reducing IR voltage drop and protecting signals), third layer (power layer), bottom layer (auxiliary signals);
• Power and ground layers must be closely adjacent, utilizing interlayer capacitance to achieve high-frequency decoupling;
• Multilayer boards can use blind vias and buried vias to connect layers, reducing surface trace space and making the layout cleaner.

VII. PCB Copper Resistors: Choosing the Right Copper Thickness to Reduce Errors
Copper traces are the core of circuit interconnects and ground planes. Excessive resistance can lead to signal errors. Remember these points:

• Standard PCBs use 1oz copper; high-power sections use 2oz or 3oz copper (copper resistivity is 1.724 × 10⁻⁶ Ω/cm at 25℃);
• 1oz copper foil is approximately 0.036mm thick, with a resistance of 0.48mΩ/square. For example, a 0.25mm wide trace has a resistance of approximately 19mΩ/cm;
• For low-impedance precision circuits (such as 16-bit ADCs), pay attention to the copper trace resistance to avoid introducing additional errors. Widen the traces or increase the copper thickness if necessary.

VIII. Grounding Design: Two Options, Choose According to Needs

Grounding is crucial for suppressing interference. Choosing the right option is important for different systems. Two mainstream methods are explained in detail:

1. Single Ground Layer (Recommended for low digital current ADC/DAC systems)

• Using a single solid ground layer allows the return current to follow the path of least resistance, avoiding mixed signal interference.
• Low-frequency return current flows along the device's ground reference line, while high-frequency return current flows back along the signal path, reducing loop interference.

2. Independent Analog Ground + Digital Ground (Recommended for complex high-current systems)

• Dividing the ground layer into analog ground and digital ground, connected via a "star ground" (the intersection point is a star ground), ensuring consistent reference levels for both.
• The AGND pin of mixed-signal devices is connected to analog ground, and the DGND pin is connected to digital ground, isolating high-noise digital current.
• Multi-layer PCBs must ensure complete isolation between the AGND and DGND planes, and overlap is not allowed.

Ⅸ. Electromagnetic Interference Shielding: Create a Faraday Cage to Eliminate External Interference

After addressing internal interference, it's crucial to protect against external electromagnetic interference (EMI). Otherwise, communication interruptions, sensor data corruption, and component failures may occur. Here are some shielding techniques:

• Use sufficient metal shielding to create a "Faraday cage," fully covering the circuit from all six sides, and connect it to the ground plane for optimal shielding.
• The shielding design must consider heat dissipation requirements and reserve signal input/output channels. Shielding should not interfere with normal circuit operation.
• For high-frequency, high-interference environments, the shielding layer must ensure seamless connection to avoid "shielding gaps."

Master these 9 hybrid PCB layout techniques. Whether you're a beginner or an experienced PCB optimizer, you can easily handle various layout challenges, directly doubling circuit stability and performance!