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发表于 2008-12-3 15:45:07
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原帖由 hym4063 于 2008-12-3 14:54 发表
谢谢!
不过我觉得比较牵强
温度上升 电路的性能是变好还是变坏?
温度升高,迁移率增大,我觉得性能还会变好啊!~
Well, I sort of remember a rough principle in devices: when temperature goes up, everything is worse.
Actually mobility goes down when temperature goes up. It is not very hard to explain this because lattice scattering increases with temperature. Please refer to the attachment. It takes me a while to find this diagram.
Take a look at the approximation of gm, gm~M*Cox*(W/L)*(Vgs-VT), when temperature increases, M decreases, and the increase in bias current cause a increase in (Vgs-Vt) term, which compensates for the decrease of mobility. Of course it is a rough argument, but it does work for many designers.
As to your another argument, yes, it is not hard to achieve a nearly flat current output with respect to temperature by summing a PTAT and an I-PTAT curernt sources.
[ 本帖最后由 waliley78751 于 2008-12-3 15:47 编辑 ] |
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mobility vs temp.
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