Die area as indicated in the top illustration.
Having said that each of the A9, A12 and A15 can be traded off for power, performance and area.
But in general the A15 offers greater performance but at greater area cost.
It is also possible that ARM is prepared to cut a deal on the royalty rate seeking a higher percentage of a higher priced SoC. However as typical royalty rates are about 2 percent of the SOC selling price that won't make a lot of difference.
Are those die photos validated ? If so the die size could range from 11 mm sq. for the Premium market down to just 5 mm sq. for the Entry level version,or in terms of area just 20 %. Does ARM's royalty fee scale with area or with functional blocks ?
They are not die photos for three different SoCs. They are the same image.
But ARM indicates the sizes of the rectangles are indicative of relative die areas for A57-T628, A12-T622 and A53-T450 mobile SoCs
ARM is losing Power battle to Intel. Intel is everywhere on new Android product announcements. Cortex-A15 is a whopper on power. 6W for Dual Core A15 is too much. ARM had to do something. Hence, A12! Lower Power on A12 means crappy performance. Intel will squish ARM
Intel has been getting some design wins but performance doesn't matter much in mobile, at least not like how it did with PCs. In that case, there was tradeoff, but with mobile, if performance means too much power, there is a high possibility the performance would be skipped. Especially when performance is usually associated with two-handed applications.
You make me think that ARM may have discovered that A15 was to be skipped, hence the A12.
BTW, ARM in is better shape than Intel in case of getting out a somewhat bad model: no G$ invested in own factory allows to quickly divert ugly duck and build a new reference more in line with customers expectations.
ARM seems to be positioninng the A12-T622 against the A57-T628, and the A53-T450 combinations for mobile SoCs.
To judge from the ARM-supplied slide the Cortex-A15's days for design-in in mobile device market have come and gone.
But does that means a flood of Cortex-A15 based devices are about to hit the market or the Cortex-A15 has come up empty?