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vbhupendra
Joined: 11 May 2005
Posts: 238
Helped: 6
Location: GOA, INDIA
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 24 Aug 2006 17:55 Guard Ring |
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| what is the difference b/w Guard ring and Substrate contacts ? How many types of Guard Rings are possible ?
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Fom
Joined: 10 Mar 2004
Posts: 761
Helped: 56
Location: Taiwan
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| 25 Aug 2006 2:31 Re: Guard Ring |
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Two types of guard ring:
- P-type contact to GND
- N-type contact to VDD
Both of them should suppress parasitic tyristor structure to prevent latchup.
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Hughes
Joined: 10 Jun 2003
Posts: 715
Helped: 85
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| 25 Aug 2006 5:42 Guard Ring |
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Guard ring may be P-Type substrate contact connected to GND or N-Well contact connected to VDD.
Guard rings are usually closed ring.
Guard ring may not be substrate/nwell contacts. A nwell ring may be a guard ring (minority guard ring)
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truebs
Joined: 21 Jan 2005
Posts: 322
Helped: 19
Location: Asia
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| 25 Aug 2006 14:58 Re: Guard Ring |
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| Guard rings may also be used to isolate some sensitive part of circuit.
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mappycarol
Joined: 26 Feb 2006
Posts: 8
Helped: 2
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| 25 Aug 2006 15:17 Guard Ring |
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| Both of them can protect circuitry from latch-up. Guardring can also isolate sensitive analog from noisy digital circuit. And please note that sometimes double guard ring is need to implement for better protection.
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leeenghan
Joined: 28 Dec 2004
Posts: 125
Helped: 7
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| 25 Aug 2006 17:20 Re: Guard Ring |
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Hi,
The following include notes on guard ring:
http://www.eda-utilities.com/CMOS_Transistor_Layout_KungFu.pdf
Page 20 to page 27.
Regards,
Eng Han
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chenjia
Joined: 16 Apr 2005
Posts: 68
Helped: 5
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| 26 Aug 2006 5:54 Guard Ring |
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| You can find more information about Guardring in book"the art of layout"
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