I came across few different ground names (digital, analog, signal, power, mecca, EM, shield, etc).
I do understand most of them - but mecca is a new one for me. Can someone please explain this mecca ground?
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1\$\begingroup\$ Its not a duplicate question. If you would have bothered reading the entire question, and not only the title, you would have seen the difference! \$\endgroup\$– KingsInnerSoulOct 9, 2013 at 16:03
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8\$\begingroup\$ Where did you see mecca? \$\endgroup\$– dext0rbOct 9, 2013 at 16:17
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3\$\begingroup\$ Apparently it's an alternative wording for "star" ground, although I've never seen it until I went googling for it. \$\endgroup\$– pjc50Oct 9, 2013 at 16:42
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4\$\begingroup\$ Vote for reopen, as the question is narrowly targeted and is not answered by the linked "duplicate" or any of the other answers linked in that question. \$\endgroup\$– PasserbyOct 9, 2013 at 16:54
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4\$\begingroup\$ hephaestusaudio.com/media/2009/11/… suggests that in the context of PCB design, "mecca ground" is a point-to-point ground, with the ground conductors being discrete traces or wires rather than a large ground plane. It further suggests that "mecca ground" is poor practice and that using a solid ground plane is preferable. It's an interesting read. \$\endgroup\$– Li-aung YipOct 9, 2013 at 18:27
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3 Answers
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Definition of mecca:
a place regarded as a center for a specified group, activity, or interest
This suggests the same as "star" topology, where items connect to a central point or "hub." Given this, I would take it to mean that grounds in the system are connected to a single common point at ground potential.
See Multipoint ground for a different grounding system.
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\$\begingroup\$ except noise, heat, and stability, what would be the difference/s between star/mecca ground to a plane/plate ground? \$\endgroup\$ Oct 9, 2013 at 20:04
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3\$\begingroup\$ Complexity of design, ease of routing, cost (primarily when you're discussing grounding methodologies in a building or factory rather than traces on a PCB). \$\endgroup\$– JYeltonOct 9, 2013 at 20:09
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\$\begingroup\$ as far as PCB design, what is a better choice for ground? star or plate? \$\endgroup\$ Oct 10, 2013 at 17:56
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1\$\begingroup\$ Personally I use ground planes with plenty of vias to reduce noise and keep return paths short. "Better" depends a lot on the type of signal you are routing on your board. High speed? High current? Every situation is different, but I don't know of any specific PCB situations where a star grounding scheme is best. \$\endgroup\$– JYeltonOct 10, 2013 at 18:06
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I feel as if the answer above is incorrect as I have done mecca grounding and in fact it it is pretty much the opposite of a single point ground. The idea is to introduce little "meccas" at each stage of circuitry of a multi-stage single ended analog circuit. Each mecca is concentrated at each stage but the circuitry and physical implementation are such that the lines between stages are run quasi-differentially. This is strictly for the signal path. Power is done in a star formation. The idea is that other ground currents can't pollute the signal when it transverses a distance because of the differential run. But each op-amp will have its own little mecca.
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\$\begingroup\$ Also, its performance yielded a 89db SNR...and this was on a wire wrap circuit....(one of those Vector cards with a plane on it) This card had 5 D/A and 2 A/D on it. It was a superior performer. \$\endgroup\$ Sep 14, 2014 at 18:06
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2\$\begingroup\$ I once heard the term "recursive star grounding" from a Ham radio guy. He was wise and had a long beard and I dared not question him. It sounds rather like what you describe. \$\endgroup\$– user98663Oct 14, 2016 at 16:34
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My understanding of this started in the early days of TV broadcast. RCA ran into the problem of ground loops between pieces of equipment injecting noise and hum. They solved it by lowering the impedance of all of the grounds by running huge woven ground busses between the equipment. Another broadcaster - if I remember correctly it was Westinghouse - solved the problem by bringing all of the grounds from the individual pieces of equipment to a single ground point, called the Mecca ground (as in "All roads lead to Mecca"); these ground lines did not need to be very big.
When I layout boards, I create separate ground plane islands for analog circuitry and each switching power supply and make their connection to the ground plane at large at the lowest impedance point which is often the ground connection at the battery if battery powered.
