Can I use the minimum size of a transistor?

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ee484

Joined: 04 Jan 2005
Posts: 161
Helped: 2

04 Mar 2007 4:24 Can I use the minimum size of a transistor?

Hi, all.

I am design a chip and I have to use a minimum size (0.4um/0.35um) and the number of gate is 1.

I am going to tape this chip out and wonder it doesn't have any reliability problem.

Anyone have a chance to use absolute minimum length and width and number of gate???

Want to hear from you guys.

Thanks,

gingerjiang

Joined: 01 Mar 2006
Posts: 212
Helped: 11

04 Mar 2007 4:41 Re: Can I use the minimum size of a transistor?

of course you can use minimum size, if your circuit run through drc check, i think there is no problem

sigui777

Joined: 25 Feb 2006
Posts: 11
Location: Texas

04 Mar 2007 6:33 Re: Can I use the minimum size of a transistor?

When using minimum size trasistors is always important how much current it will take. Not only DC but also spikes of current usually cause by parasitic inductances due to long metal routes ect. These spikes can hurt your circuit in the long run is it is to narrow.

antonio_eda

Joined: 09 Nov 2006
Posts: 112
Helped: 12

04 Mar 2007 11:41 Re: Can I use the minimum size of a transistor?

Of course, you have to check design rules as well as electrical rules of your technology. So run DRC and ERC and go Smile

dkace

Joined: 13 Jun 2002
Posts: 365
Helped: 24
Location: Greece

04 Mar 2007 14:59 Re: Can I use the minimum size of a transistor?

Better check the restriction of the Technology
Some times it is allready quite strict, but some other times you need to have just a 10% above the minimum to be on the safe side.
D.

hung_wai_ming@hotmail.com

Joined: 05 Jan 2004
Posts: 376
Helped: 39

04 Mar 2007 18:09 Can I use the minimum size of a transistor?

For most of the time, minimum size is NOT recommended though you CAN use, you SHOULD NOT use. Except one case, I think, is memory which requires minimum cell size. As long as you are doing digital design, you CAN use minimum though NOT GOOD for most of the time. For standard cell like in 0.18um, the minimum size is 0.20um which is also not a minimum. I don't think most of the designs should use minimum and I recommend you change to use bigger size for reliability issue

layout_designer

Joined: 09 Jan 2006
Posts: 88
Helped: 8

05 Mar 2007 7:25 Re: Can I use the minimum size of a transistor?

In a broad sense, digital circuits can have minimum sizes w.r.t drc. In analog randomly using minimum size will rise to lot of reliability issues.

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truebs

Joined: 21 Jan 2005
Posts: 322
Helped: 19
Location: Asia

05 Mar 2007 7:38 Re: Can I use the minimum size of a transistor?

well as far as L/W are concerned, one can freely use the minimum dimensions, as these are quite reliable on silicon.

However , we need to be careful in other minimum dimensions depending on the technologies..

kumard35b

Joined: 05 Oct 2004
Posts: 304
Helped: 111

05 Mar 2007 15:47 Re: Can I use the minimum size of a transistor?

you can use minimum sized device..but sometimes it may fail due to short channel effects..for this you need to do a spice or spectre simulation by making the input current or voltage whichever is applicable for your circuit and do DC simulation ie the circuit should operate in idle condition when no current should pass through your device..if the current consumption is minimal then you can use minimum size device else you need to increase the length by a slighter margin...so the current is minimized.