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Technology Stocks : Compaq -- Ignore unavailable to you. Want to Upgrade?

To: StockMan who wrote (10118)	12/4/1997 7:36:00 PM
From: ed	Respond to of 97611

The speed of the integrated circuit is driven by 1) short effective length of MOS transistor. 2) Small resistance on paths where electrons will flow 3) small capacitance (gate oxide , interdielectric layers) generally speaking, the higher the Vcc on a fixed channel length MOS transistor, the faster the IC, but the max Vcc which can be applied to the IC is limitted by the BVDS ( Drain-source breakdown voltage), because you do not want the transistor to be punched through which will cause troubles on the ICs.The BVDS is limitted by the effective channel length of the MOS transistors, and the speed is also controlled by the effective channel length. The larger the Leff(effective channel length) the higher the Vcc the trannsistor can bear, and the lower the speed will be with a fixed Vcc. Generally speaking with L um effective channel length, the max Vcc which can be applied to the IC without causing punching hrough on the transistor is 10L volt. So, for 166 Mhz device, you may clock the speed up to 233 Mhz, the device can still response properly. I guess there are some pins to control the speed of the CPU which were set internally on the chip for marketing purpose. A 200 Mhz chip may actually can run as high as 233 or 266 Mhz. So ,by rule and thumb, with 0.35 um process technology, the max Vcc the IC can bear witout causing punch through on ICs is approx. 3.5 volt, of course the device can be operated under vcc=2.5 volt to have slower speed or 3.5 olt to gain the max of speed.