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vbhupendra
Joined: 11 May 2005
Posts: 238
Helped: 6
Location: GOA, INDIA
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 23 Dec 2005 8:44 fringe capacitance |
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| How can we minimize the fringe capacitance ?
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qtarch
Joined: 25 Dec 2005
Posts: 3
Location: Germany
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25 Dec 2005 19:39 fringing capacitance |
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| Do not use adjacent metal layers and keep distance between wires especially differential ones.
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sunking
Joined: 25 May 2004
Posts: 914
Helped: 46
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27 Dec 2005 3:32 fringe capacitance calculation |
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| shielding can help you.
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YESH_23
Joined: 20 Dec 2005
Posts: 78
Helped: 4
Location: INDIA
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28 Dec 2005 9:25 fringe capacitance formula |
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| can u plz tell me what is Fringe Capacitance
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tuza2000
Joined: 12 Nov 2004
Posts: 142
Helped: 5
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15 Jan 2008 2:26 fringing capacitance calculation |
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Is there any material about fringe capacitance?
Anybody can upload lt?
thanks!
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milkdragon
Joined: 03 May 2007
Posts: 64
Helped: 6
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15 Jan 2008 2:56 fringing capacitance formula |
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Fringe capacitance means the capacitance from the side wall of a material to any other object around it
To minimize it, only way is to put object far apart from each other
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lladnar23
Joined: 20 Mar 2006
Posts: 221
Helped: 32
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17 Jan 2008 22:38 fringe capacitance |
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| Also make your caps have a high ratio of area to perimeter.
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protonixs
Joined: 06 Jul 2007
Posts: 122
Helped: 14
Location: SG
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22 Jan 2008 3:57 what is fringe capacitance |
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| lladnar23 wrote: |
| Also make your caps have a high ratio of area to perimeter. |
yes, larger unit area minimizes fringe capacitance.
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fly6987
Joined: 14 Jan 2008
Posts: 12
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23 Jan 2008 3:52 fringing cap |
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but larger unit area increases also unit perimeter!!!
moreover, larger unit area increases the total area of your circiut!!!
for me, the better solution is to use metal of different layer to route the circuit.
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protonixs
Joined: 06 Jul 2007
Posts: 122
Helped: 14
Location: SG
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23 Jan 2008 12:53 fringe cap |
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| fly6987 wrote: |
but larger unit area increases also unit perimeter!!!
moreover, larger unit area increases the total area of your circiut!!!
for me, the better solution is to use metal of different layer to route the circuit. |
consider having a square with an area of 4square unit.
i think the perimeter of it is lesser than the total perimeter of 4 squares having 1 square unit each. that is what i mean.
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quaternion
Joined: 12 Nov 2006
Posts: 209
Helped: 11
Location: Cairo , Egypt
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25 Jan 2008 1:40 capacitance fringe |
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| lladnar23 wrote: |
| Also make your caps have a high ratio of area to perimeter. |
I think this is to minimize the uncertainty of the cap absolute value !
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protonixs
Joined: 06 Jul 2007
Posts: 122
Helped: 14
Location: SG
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25 Jan 2008 2:03 calulating capacitor fringing |
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| quaternion wrote: |
| lladnar23 wrote: |
| Also make your caps have a high ratio of area to perimeter. |
I think this is to minimize the uncertainty of the cap absolute value ! |
yes you are right. and that uncertainty is due to the effect of the fringe capacitance.
nowadays, there is formula for getting the actual value of the capacitor and fringe capacitance is already included in the calculation.
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lladnar23
Joined: 20 Mar 2006
Posts: 221
Helped: 32
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10 Feb 2008 10:49 fringe capacitance model |
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No - the reason to maximize the perimeter has to do with the fact that fringing capacitance is proportional to perimeter of the cap. When we model a parallel plate cap, we disregard the fringing capacitance and say that all of the capacitance is due to the area. We can't make this assumption when there is a large perimeter.
Look up Hajimiri & Lee's paper of lateral flux capacitors (fractal capacitors) for more information.
As far as mismatch / uncertainty goes, Pelgram shows that the variance of capacitance is inversely proportional to cap area.
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Google
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10 Feb 2008 10:49 Ads |
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banihashemi
Joined: 25 Dec 2005
Posts: 8
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10 Feb 2008 13:53 capacitance calculation fringe |
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| Fringe capacitance depends on the layer. For metals, upper layers are thiker and so there is more fringe capacitance between two upper metal layers with the same kind.
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rexcheung727
Joined: 10 Feb 2008
Posts: 8
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10 Feb 2008 17:42 calcuration fringe capacitance |
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It may help you to understand more on Fringe Cap quantitively
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