And everything else they've done: copper interconnects, high-K gate oxide, etc. There are special effects for short channels that I don't know about, and there's also the contribution from SOI where (usually) an oxygen layer is implanted beneath the transistor, and annealed to grow a solid oxide (SiO2 glass) layer the reduction in leakage current and capacitance provides a big kick. Thanks!Įlectron mobility is higher than that, but mind it also depends on doping density, and density has been getting higher and higher as feature scales get smaller (they famously claim transistors have about one atom of dopant in them nowadays, which if you consider the volume of such a transistor, is actually an incredibly high doping rate for silicon, IIRC). If I ignore Vgs and Vt and just plug in thermal voltage, 0.0259, it actually looks pretty reasonable until the gate length shrinks to 130 nm. actual clock speed based on transistor physics. How can I figure out what gate, drain, and source voltages are? Basically I want to go from 1980 to 2004 when clock speed actually scaled and come up with a reasonable approximation of calculated vs. If a CPU lists Vccmax as 1.55 V that is the highest voltage in the CPU. How do I calculate the electric field in a CPU MOSFET? 5. What should I be plugging in for Vgs and Vt? (I think Vt should be around 0.3V) 4. Hole mobility is much lower than electron mobility so we don’t care about nMOS, pMOS is the limiter. Is 400 cm^2/V-s reasonable for electron mobility? 2. For reference the channel length of the 8088 is 3 um and it topped out at 10 MHz. I realize that equation 1 is for the ideal case and in an actual MOSFET, the effect of parasitic capacitance will substantially reduce the cutoff frequency. As I understand it, cutoff frequency is a function of electron mobility, electric field, and channel length. What I am trying to do is compare theoretical clock speeds with actually achieved clock speeds. I have picked a few CPUs from the end of each decade and started with the intel 8088. I’m ignoring turbo and only looking at single core performance.

From what I have found, the fastest manufacturer rated base clock is 4.7 GHz with the AMD FX-9590. In late 2004 the Pentium 4 570 was launched at 3.8 GHz. In the late 90’s and early 2000’s we were seeing insane clock speed increases. I’m writing a paper about the stagnation of CPU clock speed increases.

1 ghz nmos transistor