43
votes
Accepted
Why does 1/4 wavelength have a ground plane and 1/2 wavelength needs none?
I can't understand why we need to use a ground plane at 1/4 wavelength
and 1/2 wavelength not needed.
A 1/2 \$\lambda\$ dipole has voltage and current waves like this: -
Picture from Wikipedia.
...
- 466k
37
votes
Accepted
Should I really divide the ground plane into analog and digital parts?
You got to think in terms of shared impedance (not resistance, really impedance).
Consider the parts of the circuit that use GND as a 0V reference for sensitive analog purposes. Obviously you want ...
- 80.3k
27
votes
What is the best way to route a two-layer MCU based PCB?
If you really are stuck with 2 layers, then you need to be systematic, otherwise you don't have a chance. Use Manhattan routing, East-West tracks on one layer, North-South on the other, predominantly ...
- 171k
27
votes
How can I find where a short has occurred inside of a PCB?
You could connect an audio signal generator and run as much audio current as possible through the short, at something like 400 Hz or 1 kHz. Then make a pickup coil (often the iron core and coil from ...
- 931
21
votes
Should there really be 1 MΩ resistance between an anti-static wrist strap and a pc?
The 1meg resistor is needed to safeguard the user from faults from other equipment connected to mains earth.
Keep in mind that the wrist strap is a permanent connection to the electric system of the ...
20
votes
Should I really divide the ground plane into analog and digital parts?
Simply introducing SLITS into the GND plane may suffice to largely keep digital/power/relay/motor trash out of the delicate analog areas.
[ EDIT June 9 Showed a narrow region will achieve 12dB/square ...
- 34.6k
16
votes
How can I find where a short has occurred inside of a PCB?
If you apply a significant current (several amperes or more) then you can follow the path to the short by measuring voltage gradients with a multimeter on a low range (10uV or 100uV resolution, more ...
15
votes
Accepted
Should I fill free PCB space with ground?
In most cases large ground planes are a good practice to minimize EMI or to eliminate the need for running extra ground traces. However there can be special cases where you could run into problems ...
- 10.5k
13
votes
Why does 1/4 wavelength have a ground plane and 1/2 wavelength needs none?
A quarter wave monopole antenna doesn't have to have a ground plane... unless you want it to radiate EM energy with a certain efficiency and pattern.
EM radiation requires accelerating electrical ...
- 4,841
12
votes
Accepted
Can a ground plane be used as a current return path? (DC only, no signals, no AC)
Can a ground plane be used as a current return path?
The major benefit for using ground planes is that they are used for this very reason.
For instance, any circuit using a "perfect" ground plane ...
- 466k
12
votes
Accepted
The curse of the ground loop
The first one uses a star grounding scheme, which works well in some circumstances: low frequencies, absence of incoming EMI/RFI... which means it is an increasingly less useful scheme in today's ...
- 80.3k
12
votes
How can I find where a short has occurred inside of a PCB?
If you run a significant current through the board the contact spot may get warmer then the rest of the board since it has most likely the highest resistance in the path of the current.
The best ...
11
votes
Why exactly is it discouraged to gap the ground plane?
High frequency return currents want to follow the outward currents due to inductance.
If you force the return currents to take a different path then a couple of bad things happen.
You create a loop ...
- 23k
10
votes
What is the best way to route a two-layer MCU based PCB?
When designing a two-layer PCB, I think it is the most logical way to
use the bottom as the GND plane and the top as the SIG/PWR. I know I
can draw small tracks without disturbing the GND plane too ...
- 466k
10
votes
Should I fill free PCB space with ground?
Well, what would have been good advice for a 2-layer board is to use as little and as short tracks as possible on the bottom layer. So you have an as solid as possible reference plane.
As for filling ...
- 3,446
9
votes
Accepted
Should there be any PCB ground plane under a 16 MHz oscillator?
Choosing ground cutouts on the basis of the signal's speed is only part of the story. The oscillator, and the 'high speed signals' your link talks about, are different situations.
The oscillator is ...
- 171k
9
votes
Accepted
KiCad ground plane error or DRC glitch?
The thermal relief pattern around those pins indicate that the ICs pins are too close to each other for the set clearance. There is a visible bridge but it does not touch the center of the pin so the ...
- 2,161
8
votes
Should there really be 1 MΩ resistance between an anti-static wrist strap and a pc?
You have two questions which you think are related since they both concern ground connections. However the questions are not related !
Q1) The actual ground connection, where the return current from ...
- 81.1k
8
votes
Should I really divide the ground plane into analog and digital parts?
The real key is ALWAYS placement, do this intelligently and either setup can work for something like this, get it too badly wrong and not only will the board be very hard to route, but it will be hard ...
- 17.6k
8
votes
What's the best ground topology for this mixed signal board?
Let's get one thing absolutely clear: split/partitioned ground planes are never necessary, but they can be a useful technique to mitigate human error. But you can always achieve equal or slightly ...
- 29.1k
8
votes
What is the best way to route a two-layer MCU based PCB?
Using the bottom layer as GND plane is only possible for the simplest circuits due to congestion as you have noticed.
You can go a bit further if you abandon the idea of a ground plane for 2-layer ...
- 22.7k
7
votes
Bonding yourself via GND pin of an USB-port?
You should NOT connect your anti-static gears to USB ground pin. The USB ground is SIGNAL GROUND. An ESD event can surge along the signal ground and elevate its potential relative to other ICs inputs (...
- 41.8k
7
votes
Accepted
PCB Layout Help (with schematics!) - Split ground plane or not?
Replying as one nonEE who did his share of circuits to another nonEE...
First of all you have a clean schematic and a clean layout, so chances are things will just work as they are already. This is ...
- 196
7
votes
Accepted
Does putting solder mask over a ground plane influences its heat exchange with the air?
The short answer is no it won’t make a significant difference. The long answer is that conduction will be slightly worse with solder mask but radiation will be better, assuming that the bare metal is ...
- 7,525
7
votes
Confining signal using stitching vias on a 2 layer PCB
I think we should separate the informal terms "via stitching" and "via curtains".
Via stitching = keeping several ground planes together to reduce noise, minimize impedance/...
- 21.6k
7
votes
Accepted
Is it bad practice for audio inputs and outputs to share a common ground?
In general the outputs have to share the ground with the inputs in audio amplifiers.
However, a lot of effort is needed to ensure that the high-currents flowing in the output do not contaminate the ...
- 33.8k
6
votes
Accepted
Why use a localized ground plane?
It's not just all about loop area. Small loop area is important to reduce radiation and susceptibility, but I expect you want your circuit to do more than not radiate anything.
Currents across a ...
- 314k
6
votes
Accepted
How to make a ground plane for relay PCB switching mains?
Definitely do not extend the ground plane into the mains area.
The relays are providing your safety isolation here. Draw a line (real or imaginary) across the middle of all the relays. Keep all low ...
- 171k
6
votes
Accepted
Altium split power plane
To split the plane you have to place lines on the plane. Place >> Line and by pressing tab you can adjust the width of the line.
The line represents places where no copper will exists. You can then ...
- 541
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