Originally published at: https://www.protoexpress.com/blog/how-to-design-mixed-signal-pcb-with-signal-integrity/
Designing mixed-signal PCBs presents unique challenges in managing the interactions between digital and analog signals. Digital circuits generate noise due to switching operations, which can interfere with sensitive analog components. By isolating the analog and digital components, implementing the right signal protocols, and providing short return paths you ensure a reliable mixed-signal board. In this article, you’ll learn the steps for designing mixed-signal PCBs while addressing the common challenges you might face. Highlights: Segregate digital and analog components such as microcontrollers, FPGAs, OPAMs, filters, and sensors. Select components with appropriate signal interfaces. Place ground planes efficiently to minimize interference. Distribute…
How do I determine the best way to partition analog and digital sections?
What considerations are crucial for clock placement?
To partition analog and digital sections effectively, physically separate them on the PCB. Assign dedicated areas for each, minimizing overlap. For multilayer designs, allocate separate layers for analog and digital sections.
Keep high-frequency digital signals, such as clocks, away from sensitive analog circuits. Route analog signals with minimal trace length and avoid crossing noisy digital paths. Consider using shielding, filtering, and proper decoupling to prevent interference. This strategy ensures signal integrity and reduces noise.
When placing clocks in a mixed-signal PCB design, position them as far as possible from analog circuits to minimize noise interference. Use short, direct signal paths for clock traces to reduce signal degradation and minimize the impact of parasitic inductance. Consider the use of shielded traces or ground pours around the clock trace to isolate it further.
Ensure proper termination and impedance matching to avoid reflections and maintain signal integrity. Finally, ensure that any clock-related components like buffers or drivers are placed close to the clock source to maintain timing accuracy.