By Don Scansen, EETimes (November 13, 2020)
Recent angry comments to EE Times‘ interview with Intel’s Ramune Nagisetty disparaged the current heterogenous integration and chiplet discussions as more of a rehash than an innovation and furthermore simply a way for American manufacturers to obfuscate their inability to stay at the leading edge of wafer fabrication. Although a great deal of the package-level integration that has been discussed is not ground-breaking innovation, there is little doubt that we are in the middle of a significant shift in integration away from system-on-chip (SoC) design.
Espousing the virtues of the SoC approach after that introduction is odd timing, but the latest foray into chip design at Apple was just announced. The M1, based around a custom piece of Apple SoC silicon, will power the new Macbook Air as well as some Macbook Pro and Mac Mini models. If we can take the promotional images provided by Apple at face value, calling the M1 processor die an SoC is certainly no understatement. Taking all due blame for my focus on the chiplet approach to integration, there is none of that here. Looking at the M1 die photo from Apple, breaking this type of design up into chiplets would not be an attractive prospect. The additional interconnection and communication overhead would create more headaches than it’s worth.
The other argument in favor of the SoC approach for Apple is that they are mostly past the point of using anyone else’s physical layout IP cores. They are responsible for the bulk of all the circuit blocks and focusing their efforts on keeping tight control over physical design and the hardware-software integration to optimize the system and (presumably) improve the user experience. They wouldn’t be buying either a vendor designed piece of silicon or hard IP core to be stitched into their processor design.
Before comparing the pure SoC design to current layouts that might be more amenable to a chiplet approach, there are a couple more things to mention about the M1.