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Shoaib Mustafa , 06-18-2026, 08:18 PM

Hi. I am designing a circuit for driving a large loop for magnetic coupling with a reader. I've calculated and ran a few simulations. in all the results the answer can back to use a capacitor of 97nF considering that my loop (rectangle single wound) is about 16uH. Please ignore the capacitor value in this image. i miscalculated here.

I'd just like to know if it will actually achieve resonance with this and provide near field coupling to an appropriate reader? i've never designed such a system so finding it hard to trust just the equations without any advice from someone who's tried it.

, 06-18-2026, 08:23 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:
Based on the video content, here's what you need to consider for your magnetic coupling design:

1. **Resonance Fundamentals**: Your 16μH loop with 97nF capacitor creates a resonant frequency of ~127kHz (using f=1/(2π√(LC))). This falls within typical near-field communication ranges (125-134kHz), so the math checks out. [Relevant LC resonance discussion](https://www.youtube.com/watch?v=J4UUGSIP770&t=2559)

2. **Parasitics Matter**: Real capacitors have equivalent series inductance (ESL) that affects resonance. A 97nF ceramic capacitor in 0402 package has ~0.5nH ESL, which would shift resonance frequency slightly. Ensure your simulation includes these parasitics. [Capacitor parasitics explanation](https://www.youtube.com/watch?v=J4UUGSIP770&t=2735)

3. **Coupling Efficiency Depends On**:
- Loop area (larger = better coupling)
- Alignment with reader coil
- Quality factor (Q) of your resonant circuit
- Distance between coils

4. **Practical Verification Steps**:
- Use vector network analyzer to measure actual resonance
- Check field strength with near-field probe
- Experiment with capacitor values ±20% to account for parasitics
- Consider using multiple smaller caps in parallel to reduce ESL

[Example of resonant circuit analysis](https://www.youtube.com/watch?v=Tt8X6_maj6c&t=1932) shows how component interactions affect actual performance.

While your calculations appear correct, successful magnetic coupling requires careful physical implementation.

, 06-18-2026, 08:23 PM

Start with prototype testing at varying distances (1/4 wavelength rule doesn't apply in near-field), and monitor the reader's response during tuning.

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

QDrives , 06-19-2026, 10:52 AM

You only show half of the circuit and no details on the IC.

Shoaib Mustafa , 06-20-2026, 09:59 AM

Oops. i'm sorry. The IC the h bridge driver DRV8837