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Who have seen such layout?

 
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staric



Joined: 26 Sep 2003
Posts: 79
Helped: 1
Post09 Aug 2004 15:42   Who have seen such layout?
The layout is drawn in the picture. The yellow area is Gate. The wide wire area are active area. And from layout, the active area of Drain and Source aren't seem to connect. I cannot sure the picture is correct. But I have not seen this layout. Who can tell me the functional of this device? And its advantage?

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piao



Joined: 12 Feb 2003
Posts: 223
Helped: 7
Post09 Aug 2004 16:14   Who have seen such layout?
This should be a HV mos transistor, when the voltage is high, the transistor is turn on, the channel will shaped.
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Nobody



Joined: 04 Oct 2001
Posts: 250
Location: Formosa
Post09 Aug 2004 17:05   Who have seen such layout?
It avoid the high density eletric field in one side by extend the drain LDD. Look chap12 of "The art of analog layout " . You can find this book easily in this forum .
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just4you



Joined: 02 Dec 2002
Posts: 25
Post09 Aug 2004 19:29   Re: Who have seen such layout?
This is a highvoltage transistor (LDMOS). The highvoltage capability is build of the extention of a well from the drain side of the transistor and by increasing the channel resistance.
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duron999



Joined: 07 Jul 2004
Posts: 55
Post09 Aug 2004 19:57   Re: Who have seen such layout?
High voltage Transistor
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gqxfw



Joined: 03 Jul 2002
Posts: 32
Post10 Aug 2004 3:24   Re: Who have seen such layout?
I think also it is a High voltage Transistor
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rajesh13



Joined: 07 Jul 2004
Posts: 126
Location: Milky Way
Post10 Aug 2004 6:19   Re: Who have seen such layout?
Yes, this is LDMOS. As you can see that the drain is not overlapping with the gate. Some series resistor is there with the channel.
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Colbhaidh



Joined: 10 Aug 2004
Posts: 151
Helped: 16
Post10 Aug 2004 12:16   Re: Who have seen such layout?
This might help visualise the LDMOS

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rambus_ddr



Joined: 26 Jun 2001
Posts: 119
Helped: 4
Post12 Aug 2004 4:21   Re: Who have seen such layout?
I don't think it is a HV MOS, because the source (or drain) is not under poly. So the on channel is not created. I think it maybe a ESD protect MOS.
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Colbhaidh



Joined: 10 Aug 2004
Posts: 151
Helped: 16
Post12 Aug 2004 9:37   Re: Who have seen such layout?
This is definitely an LDMOS transistor. What is missing is the N-Well beneath the isolation - see cross section posted earlier.
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coluga



Joined: 12 Aug 2004
Posts: 4
Post12 Aug 2004 14:01   Re: Who have seen such layout?
LDMOS
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rambus_ddr



Joined: 26 Jun 2001
Posts: 119
Helped: 4
Post15 Aug 2004 3:25   Re: Who have seen such layout?
How does it became 'ON'?
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chun_hung86



Joined: 13 Aug 2004
Posts: 10
Post23 Aug 2004 17:04   Who have seen such layout?
what is LDMOS? who can tell me, thx.
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okguy



Joined: 01 Mar 2002
Posts: 563
Helped: 6
Post24 Aug 2004 3:34   Re: Who have seen such layout?
Detailled information maybe found in this book :
"High Voltage Devices and Circuits in Standard Cmos Technologies"
by Hussein Ballan, Michel Declercq
http://www.wkap.nl/prod/b/0-7923-8234-X
http://www.amazon.com/exec/obidos/tg/detail/-/079238234X/103-9712961-0986269?v=glance&vi=contents
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sunking



Joined: 25 May 2004
Posts: 914
Helped: 46
Post26 Aug 2004 7:38   Re: Who have seen such layout?
It should be a HVMOS.

Most LDMOS is drawn as a circle or something like it
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rickhsu



Joined: 31 Jan 2004
Posts: 20
Post30 Aug 2004 6:41   Re: Who have seen such layout?
a paper about this kind of cmos

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r23718



Joined: 01 Sep 2004
Posts: 6
Post01 Sep 2004 8:07   Re: Who have seen such layout?
seen that as ESD on output buffer
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roadz



Joined: 07 Sep 2004
Posts: 1
Post07 Sep 2004 9:39   Re: Who have seen such layout?
Surprised
I think this is an ESD transistor.
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zx2051



Joined: 23 Oct 2003
Posts: 20
Post07 Sep 2004 10:49   Who have seen such layout?
why the contact size are not same ?
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leo_o2



Joined: 03 Sep 2004
Posts: 356
Helped: 22
Post09 Sep 2004 3:51   Re: Who have seen such layout?
Yes. It should be a unsymmetrical HV MOS. Left will be source and right will be drain that will sustain the high voltage.
ESD devices only need unsymmetrical space for drain and source but no need for diff.
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