Gene Frantz
TI Principal Fellow and Business Development Manager, DSP

Now that I’ve committed the unthinkable heresy of questioning the continued validity of Moore’s Law, let me try to explain how we are compensating for the physics that have caused this stir.

First, I mentioned that performance, in terms of clock speed, has not followed Moore’s prediction for the last decade or so. So how have we managed to keep increasing it? For example, with DSPs, do you increase the clock or do you increase the number of multipliers to increase performance?

Our answer has been to increase the number of multipliers. If we look back at the C1x, we had one multiplier per clock cycle. By the time we developed the C64x, we had four multipliers per clock cycle. And with the new DaVinci SoC, we have eight multipliers per clock cycle. In this way, we compensate for the drop off in performance that is caused by physics. Moore’s prediction never told us about that.

In terms of power, there are a couple of things we are doing. First, because temperature adversely affects power, we have to be better at managing temperature. Creating better insulators is one way of handling this. Another is by being economical with power. How many times did your mother or father tell you to turn off a light when you leave a room? This same good sense can be used in a DSP. We can tell certain parts of the chip to turn off when they are not being used, saving power for the necessary functions at that time.

Ironically, you can save power by using more transistors. Seems counterintuitive, doesn’t it? But if I am using One million transistors operating at 1G, I can get the same performance out of two million transistors operating at .5G. But the power dissipation will be down because the .5G transistors can run at a lower voltage. And, power dissipation is a square function of the voltage.

So, it is clear that we will have to continue to be creative. Moore’s Law, in terms of the number of transistors doubling (his prediction in 1965), will continue to hold true for the foreseeable future (perhaps the next couple of decades). But we will have to continue to find ways to maximize performance while cutting power by using more transistors. Moore didn’t warn us of this twist in the technology either.

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