Questions tagged [shielding]

Questions regarding shielding devices against noise, interference, or ESD. Not to be confused with arduino-shield.

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53
votes
12answers
65k views

How to connect USB Connector shield?

How should I route USB Connector shield on PCB? Should it be connected to GND plane right where USB is placed, or should the shield be isolated from GND, or should it be connected to ground through ...
13
votes
3answers
2k views

Does Shielding “Electrically” shield “Magnetically” too?

I know it sounds like a newbie question but I can't wrap my mind around it. An electromagnetic field is electric + magnetic field. So this means that when shielding an equipment offensively, for ...
11
votes
1answer
3k views

USB 3.0 Hub shield connection

This is about the seemingly controversial shield to ground connection. The system is basically a body-worn intel-based computer, powered by a battery. Two USB 3.0 (or 3.1 Gen1) cables come out to a ...
29
votes
6answers
12k views

Noise reduction strategies in electrophysiology

When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio. These signals are usually in the 10uV ...
9
votes
1answer
2k views

Does an ungrounded shielded cable shield at all?

Does a shielded cable provide any shielding if the shield isn't grounded? Would it be practically different than an unshielded cable?
4
votes
2answers
5k views

EMI/RFI emissions and computer cases

I have designed a computer case (enclosure) for mini-itx motherboards. Its bottom and rear are made out of 2mm thick aluminium and the sides and top out of 4mm plastic (ABS). I'd like some advice ...
2
votes
1answer
1k views

Portable device shielding & ESD

I'm working on a portable battery-powered device with a shielded I/O connector for sensors, but I'm confused about how to properly ground the shield and ESD array. Here is a block diagram of my ...
14
votes
3answers
7k views

How to Connect USB/Ethernet Shields to Chassis or Digital Grounds

I have a PCB with a few USB and RJ-45 Ethernet connectors on one side. I'm quite confused as to how exactly I'm supposed to be hooking up the SHIELD pins on them though. This is for a host device ...
15
votes
2answers
2k views

Grounding PCB to enclosure

I am designing a small sensor which fits into a custom aluminum enclosure. The sensor uses CAN bus and a long cable to connect it to the host and power. The shield of the cable will ground the ...
11
votes
2answers
2k views

Can a shield propagate EMI?

At a job site we typically have 10 vehicles connected to a single vehicle (star layout) by a 100m 5 conductor cable carrying power(unused), ground, shield, CANH, and CANL. The shield is grounded on ...
4
votes
1answer
2k views

What is the effect on noise immunity of a floating shield on a shielded twisted pair

We have an installed system where resistive sensors are connected to some electronics by shielded cables of between 2 and 10 metres. The cable is a twisted pair sheathed in a stainless steel braid. ...
5
votes
3answers
5k views

Non-metal cases

This question is really aimed at computer cases, but I suppose it also applies to other PCB cases. Most of the Computer cases I come across are aluminium, or else some other metal; As I understand it ...
4
votes
2answers
1k views

Where to connect shield and ferrites in PCB with isolated planes

I have a device which has two sections of the PCB completely isolated form each other, but connected by an isolator IC (PN: ????). I think I need to shield the whole device for reducing EMI because ...
3
votes
1answer
1k views

Benefits of top and bottom ground pour in multilayer boards with proper ground plane layers and stackup

I'm trying to get some analytical feeling for the use of ground pours on bottom and top layer in multilayer boards with proper stackups such as (for example). Top Gnd Sig1 Power Power Sig2 Gnd ...
3
votes
4answers
386 views

Electromagnetic shielding and EMP

I've asked several related questions, but I'm afraid that some of the answers that I received, while great answers, might be skewed because of incorrect assumptions or unclarity in my questions. The ...
1
vote
1answer
415 views

Minimize crosstalk using shield/guard trace with capacitor ground

I'm designing a PCB using this component http://www.ti.com/lit/ds/symlink/afe4403.pdf And from the datasheet page 90 layout guidelines I found point(2) which says If the INP, INN lines are required ...
3
votes
1answer
426 views

How much shielding does an ungrounded metal box provide?

How much shielding does an ungrounded metal box provide? That is, a circuit is in a metal box but the box is not connected to either circuit ground nor externally earthed
3
votes
1answer
152 views

Analogue (or digital) signal integrity with multiple sources of noise

tldr: Can I transmit an analog signal through a noisy environment without it being corrupted, or should I use a digital signal instead? My requirement is to transmit a signal from a MA3 absolute ...
3
votes
1answer
2k views

Is it OK to place ground plane under transformer?

I have a large transformer (50kHz, ferrite E-core) on the PCB. I want to pass power rails under it on the bottom layer. Should I place a large ground plane on the top layer to shield these power rails ...
3
votes
3answers
2k views

Why is a caseless PC not an EMI problem?

As I understand it, the case of a PC is metal so that it can form an EMI enclosure around the electronic parts. My view is reinforced by there being conductive fingerstrips around the mating edges. ...
3
votes
2answers
3k views

Does the “drain” wire in a microphone audio cable serve any purpose the shield does not?

I'm helping a friend with an audio installation, and he asked about the requirements for the microphone cable: "Wiring Requirements: 2 Conductor shielded cable, 22 gauge with a 24 gauge drain wire. ...
2
votes
0answers
2k views

Understand the shielding of a USB device

I have a GPS PCB which has regular USB pinouts (GND, +5V, DATA- and DATA+), but in addition has one stranded wire which is connected to USB type A plug. Marked as "USB connector" on the image: What ...
2
votes
1answer
892 views

ungrounded chassis shielding

I'm looking into whether an ungrounded metal box provides good/bad EM shielding. This thread seems like a definite "good", for reasons of the box acting as a faraday cage : How much shielding does an ...
2
votes
1answer
1k views

Connecting the Shield of a strain gage cable connector to PCB with ADC

I have a half-bridge strain gage sensor (pre-assembled product) with a 30cm cable, which I am trying to interface with my PCB containing a 24-bit ADC. The connector at the cable end toward the ADC (i....
2
votes
3answers
642 views

Connect signal ground to safety ground?

We are designing a product which has to meet EMC directives. It consists of metal backplate folded into a chasis (the front is open). on the backcover there is a SMPS mounted. and on top of this we ...
1
vote
1answer
193 views

USB shield for analog and digital ground?

I'm new to Mixed-signal design and I'm having trouble deciding how to connect my digital and analog ground. I'm doing a 4 layer design, so I have a split ground plane. As I understand, since I'm ...
0
votes
4answers
225 views

Can a “static” magnetic field carry Information? [closed]

Information is electronically represented as some energy that is changing, therefore we measure an on state (1) and an off state (0), to create a (0,1) binary representation of the information. Now a ...