Hobbyists, students, even engineers tend to pay more attention to circuits, the latest components, and code as important parts of an electronics project, but sometimes neglect a critical component of electronics --- the PCB layout. As a Chinese saying goes, well begun is half done. Good PCB layout plays a great important role in your PCB projects, because poor PCB layout can cause function and reliability problems.
Make Loops Small: Loops, especially high frequency loops, should be made as small as possible. Small loops have lower inductance and resistance. Placing them over a ground plane can further reduce inductance. Small loops also help reduce the amount of signals that are inductively coupled into the node from external sources, or are broadcast from the node.
Decoupling Capacitor Placement: Place decoupling capacitors close enough to the power and ground pins of integrated circuits to maximize decoupling efficiency. Kelvin Connections: Kelvin connections are made at the exact points to reduce stray resistance and inductance. For example, Kelvin connections for a current sense resistor are placed exactly at the resistor pads. Placing the connections at the resistor pads may look the same on your layout, but real traces have inductance and resistance that could throw your measurements off if you don’t use Kelvin connections.
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