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PSoC™ 4

YuMa_1534086
Contributor

Hello.

Below is description of CapSense application note(AN64846) about proximity sensor.

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Wire:

A single length of wire works well as a proximity sensor.

The proximity distance achieved with a wire loop sensor is higher compared to a PCB trace.

But using a wire sensor is not an optimal solution for mass production because of manufacturing cost and complexity.

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Why is the proximity distance of wire method higher than PCB trace method?

Does not wire method’s noise become larger than PCB trace?

Because wire method can not have both GND/Shield mesh pattern and GND loop around proximity sensor.

Best Regards.

Yutaka Matsubara

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BragadeeshV
Moderator
Moderator

Hi YuMa_1534086​,

The proximity distance achieved using a wire loop is more or less the same as achieved using a 1.5 mm PCB trace width loop of the same diameter.

Wire loops are more susceptible to noise since we can not have a ground loop near it. Also, it is not possible to restrict the field lines as much as we can control in a PCB trace. One more issue is that since wire is a mechanical part, there are chances of it getting broken or displaced. These could cause measurement errors.

In terms of noise immunity, it is better to choose a proximity trace with a ground loop around it.

Hope this answers your question.

Regards,

Bragadeesh

Regards,
Bragadeesh

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