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Evans Thomas , 07-17-2026, 05:58 PM

Hello, just recently I learned that it is the inductance that matters than the capacitance (video to watch: https://youtu.be/ARwBwHZESOY?si=6IpNp6nd6Ufkhdtq). So I'm thinking it's best to pour copper and place the capacitors as near as possible and so "routing through the pads" of the bulk caps is probably worse. Is that correct? here I have two IMUs (top-left and right edge) and at the middle is an LDO. Here I had routed through the bulk cap. Can I replace that whole region with a copper pour?
Thanks

, 07-17-2026, 06:03 PM

🤖 In the meantime, here’s a response from the [FEDEVEL AI HW Assistant]().
It helps to find relevant resources for your question, but it may make mistakes as it’s still in early development.

This is the response from the AI Assistant:
You're absolutely right to focus on minimizing inductance in power delivery. Based on the video content:

1. **Key Insight**: Inductance matters more than capacitance for high-frequency power delivery. The critical factor is creating the lowest-inductance path between components, not just adding bulk capacitance. [Source 14](https://www.youtube.com/watch?v=ARwBwHZESOY&t=2669) shows how even small capacitors placed close to devices outperform larger ones with longer paths.

2. **Routing Through Capacitor Pads**: This introduces unnecessary inductance. The ideal flow should be:
- LDO output → **immediate decoupling capacitor** (placed as close as possible to LDO)
- Then to bulk capacitor(s)
- Finally to load devices
[Source 3](https://www.youtube.com/watch?v=_DzpaKlDsWs&t=876) demonstrates poor practice where capacitors are placed too far from regulators.

3. **Copper Pour Strategy**:
- Use a solid power plane (copper pour) whenever possible - it provides lower inductance than traces
- Place **all capacitors directly against the plane** using short, wide connections
- Avoid routing other signals through the power plane area under capacitors
[Source 7](https://www.youtube.com/watch?v=WdlN8bHw-w0&t=1095) explains how plane geometry affects inductance

4.

, 07-17-2026, 06:03 PM

**Critical Layout Tips**:
- Position the LDO's output capacitor **first in the chain**, directly at its output pin
- Bulk capacitors should be placed closer to the loads (IMUs) than to the LDO
- Use multiple vias in parallel when transitioning layers (reduces via inductance)
[Source 17](https://www.youtube.com/watch?v=yptbPYe1BL0&t=1360) shows good via placement for power

For your specific case: Yes, replace the trace-through-capacitor layout with a copper pour. Place the LDO's decoupling cap adjacent to its output pin, then route through the pour to bulk caps and IMUs. Keep high-current loops small by arranging components in sequence: LDO → decoupling cap → bulk caps → IMUs.

Remember: Every millimeter of conductor between components adds inductance. The video you referenced ([Source 6](https://www.youtube.com/watch?v=bdhx7Ir_2Ws&t=0)) demonstrates how proper placement can reduce noise by 10x through inductance reduction alone.

You can continue chatting with the AI Assistant here:
https://fedevel.com/hw-assistant

QDrives , 07-17-2026, 09:43 PM

So how fast and with what current do you switch?

Evans Thomas , 07-18-2026, 05:16 AM

Switch? Well the devices are IMUs and draw less than a milliamp but I have all this space ans so would like the least noise

QDrives , 07-18-2026, 04:11 PM

Switch yes. How else do you get your data out of it?
I2C, SPI, parallel, etc.?

Evans Thomas , 07-18-2026, 05:51 PM

Oh you mean clock freq? Maybe max 16MHz SPI

QDrives , 07-18-2026, 07:55 PM

3.3V, 50 Ω transmission line -> 66mA.
3.3V, 4.7kΩ pull-up -> 0.7mA (per line).

Evans Thomas , 07-19-2026, 03:49 AM

@QDrives drives rives Okay so the trace are probably enough but can you tell me of a pour there is better?

QDrives , 07-19-2026, 09:06 PM

Better how? The few uΩ and fH?

Evans Thomas , 07-20-2026, 02:53 PM

Just general routing advice

QDrives , 07-20-2026, 06:27 PM

No, it will not help. Nor will it be negative.
So go for the one that is best for copper balancing.

Evans Thomas , 07-21-2026, 07:22 PM

Okay thanks