kc5tja wrote:
(2) The conclusion exposes the author's complete misunderstanding of the purpose for using asynchronous logic. Even if you use an asynchronous CPU in an otherwise synchronous environment, you get the benefit of a chip which draws significantly less power (if implemented correctly; I'm not sure this would work in an FPGA environment), is much quieter in terms of RF hash, and which produces substantially less heat. These all can be extremely valuable qualities. For example, on an Intellasys SEAforth 24A chip that I have, I had all 24 cores running full blast at an estimated 650 MIPS each, and that chip only became two degrees warmer. ONLY two degrees! And, if my ham rig is any indication, it had no observable hash emissions; everything it put out was well below nature's own noise floor. Contrast this against my desktop PC, whose emissions are so strong I can hear it in my headphones when the sound card is silent.
With desktop class IC processes, an asynchronous processor consumes far more power than a synchronous one. Why? Because leakage current is higher than switching current. Modern processors use FETs with threshhold voltages of 200mV, and 1V power supplies. Therefore, power consumption is linear with powered transistors; clock frequency is not a major factor. Asynchronous designs, as we have established, use more transistors.
...
I'm currently working in the VLSI group of a microprocessor company. From what I've heard, over half of our power budget is used by leakage current. So clock gating doesn't seem to help very much.
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