[SI-LIST] Re: The effect of temperature on the speed of IC
- From: Pramod Parameswaran <eppramod@xxxxxxxxx>
- To: Christopher.Jakubiec@xxxxxxxxxxxx, si-list@xxxxxxxxxxxxx, tom@xxxxxxxxxxxxx, zhang_kun@xxxxxxxxxx
- Date: Thu, 7 Jul 2005 09:42:14 +0530
Hi,
I agree with Chris that we can see opposite effect for CMOS also.
What i understand is that there are two main things which we need to
consider here
1,Threshold Voltage,which exhibits negative temperature Coefficient of
Resistance
ie,for High Temp Vt is less and for low temp Vt is high..
2,Mobility ,which has positive temperature Coefficient of Resistance.
ie,normal low temp mobility is more(though there are some very low temp w=
here
we can observe lesser mobility,due to different scattering effects)
and for high
temperature Mobility will degrade...
So if you see vgs vs id (say for a diode connected MOS), as mentioned
in the paper
we can notice a bias point(vgs,id) which is independant of
temperature, MOS diode a simple voltage reference....!!!.
So basic observation leads to the fact that for low gate source
voltages, threshold voltage determines the turn on characteristics
and so we have lower currents(lower speed) for decresing
temperatures,but once we are in fully turned on condition,mobility
starts kicking in and there we will have opposite effect.(higher speed
for lower temperature)
Regards,
Pramod
LSI Logic Corp.
On 7/6/05, Christopher.Jakubiec@xxxxxxxxxxxx
<Christopher.Jakubiec@xxxxxxxxxxxx> wrote:
> Tom,
>=20
> I agree with you in general regarding the CMOS process speed increasing
> with decreasing temperature, however I have also read literature related
> to low threshold voltages & low drain to source voltages that display
> the opposite effect.
>=20
> Refer to: http://lowpower.iis.u-tokyo.ac.jp/SPN/2001/20010371.pdf
>=20
> Regards,
>=20
> Chris Jakubiec
> Infineon Technologies
>=20
>=20
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Tom Dagostino
> Sent: Tuesday, July 05, 2005 8:59 PM
> To: zhang_kun@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: The effect of temperature on the speed of IC
>=20
>=20
> That is almost correct, for CMOS processes speed increases at lower
> temperature, for bipolar processes speed increases as temperature goes
> up.
>=20
> Tom Dagostino
> Teraspeed(R) Labs
> 13610 SW Harness Lane
> Beaverton, OR 97008
> 503-430-1065
> tom@xxxxxxxxxxxxx
> www.teraspeed.com
>=20
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> 401-284-1827
>=20
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of zhangkun 29902
> Sent: Tuesday, July 05, 2005 4:39 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] The effect of temperature on the speed of IC
>=20
>=20
> Dear all
>=20
> I have a simple question about the effect of temperature on the speed of
> IC. One of my colleagues told me:
>=20
> 1.For TTL buffer, the speed of IC will increase while the
> temperature is increasing.
> 2.For CMOS buffer, the speed of IC will increase while the
> temperature is descreasing.
>=20
> Is it right?
>=20
> Best Regards
>=20
> Zhangkun
> 2005.7.6
>=20
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