Re:Why has CPU frequency ceased to grow? (2014)
by deepnotderp on Wednesday February 21, 2018 @04:21PM
(#16433077)
1. Compound semiconductors often suffer from p-type and n-type conduction problems. Plus they're ridiculously expensive and power hungry. They also often lack a native oxide.
2. The problem today in CPUs is not really clock speed but much more the memory access latency, optane is much slower* than DRAM and has much lower endurance.
*Even though silicon HKMG transistors use high k gate dielectrics now, they still use a silicon dioxide interfacial layer.
From reading the open literature and advertisements by foundry companies, I think you could make a 6502 equivalent processor with Indium Phosphide with 64kb of static RAM that clocks at 30 GHz. With a more refined process you might push 90 GHz and a much more complex processor.
Yes, InP is more expensive than Silicon but part of that is the low volume that InP parts are made in. Advances in Silicon are getting much more expensive, and one InP microprocessor could do the work of ten Silicon-based cores so you can save on die area without the "race to the bottom" in size.
The main issue with high clocks is fast access to memory, probably you would need an optical interface to off-chip RAM, also I don't know what the InP equivalent of DRAM is. (Something like Optane?)