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Inside the Apple iPad 4 – A6X a very new beast!

Inside the Apple iPad (version 4)The focus of this piece will be on the A6X as well as showing die images for several of the packages with unidentified markings.The most obvious overall conclusion we can come to, is that this new iPad continues the Apple tradition of re-use among their hand-held devices.(click any shots to enlarge)
Apple iPad 4 Circuit Board side AApple iPad 4 Circuit Board Side B
Inside the Apple iPad (version 4)A little closer look at the board.
The A6X Processor – a new beast on the block!This is not just an A6 with a couple minor tweaks. The A6 is 94mm2 while the A6X is 123mm2 – a full 30% larger.So where did that extra area go? Well, firstly, it did not go to the CPU core. The A6X uses the identical CPU to the A6. Same size, same layout. This is not surprising given that the prior CPU used custom layout techniques, and therefore it would be a huge amount of work to redesign so soon. Much of the extra area has gone to the GPU cores which are up from 3 to 4. More notable is that each of these GPU cores is much larger.On the A6X each GPU core is 8.7mm2 while the A6 GPU cores are only 5.4mm2. The overall area occupied by the A6X GPU cores is more than double that of the A6!
Apple A6X Polysilicon Photo - AnnotatedApple A6X Top Metal Die Photo

So we see that of the 29 mm2 of new area on the A6X, a full 18.6 mm2 is the result of the increased quantity of graphics processing. Impressive!Additionally, if you look closely at the GPU cores (which our high magnification scopes allow us to do), we can see they are actually split into sub-cores themselves. Each GPU core is sub-divided into 9 sub-cores (2 sets of 4 identical sub-cores plus a central core). This could be done to allow for more efficient parallel processing, or to allow for a higher maximum clock rate. In either case, these GPUs should result in some blazing graphics on your iPad.Other items of note:

  • It looks like the A6X has double the SDRAM interface width of the A6 (again likely to allow for greater graphics processing power).
  • Other than the CPU, it appears all the other digital cores have new layouts. This chip is not just a minor tweak from the A6, a lot of work has gone into this.
  • Apple has reduced the number of core PLLs needed from 9 on the A6 to 8 on the A6X. However they have moved them close to the middle of the chip which may allow for better control over clock skew across the chip.
  • Many of the analog and interface cores have been reused from the A6, however there are also some new interface blocks.

 For those interested in a visual representation of the size difference, here are two scale images that compare the two die at polysilicon.

Apple A6 Die

Apple A6 Die at Polysilicon (9.6 mm x 9.8 mm)

Apple A6 Die

Apple A6X Die at Polysilicon (10.4 mm x 11.9 mm)

On the process side of things, a SEM cross section reveals the contacted gate pitch and metal gates consistent with Samsung’s 32 nm HKMG process.

Samsung 32 nm HKMG Process in the A6X

Samsung 32 nm HKMG Process in the A6X

Samsung 32 nm HKMG Process in the A5

Samsung 32 nm HKMG Process in the A5

The Image SensorsThe first one at right is the 5 Mp primary sensor by OmniVision, with markings OV290BA.The second one at right is the 1.2 Mp secondary sensor by OmniVision, with markings OV23CB.
Apple iPad 4 Primary CameraApple iPad 4 Primary Camera Die MarkingApple iPad 4 Secondary Camera Apple iPad 4 Secondary Camera Die Marking

A catalog of the devices (over half are in the lab for die photos)

Maker Package marks Device type
Apple A6X / APL5598 343S0635 Applications processor
AKM 8975 / B227T Electronic compass
NXP 1608A1 Unknown
Apple 343S0622-A1 Dialog Semi PMIC
Apple 338S1077 Cirrus Logic Class D Amplifier
Apple 338S1077 Cirrus Logic Class D Amplifier
Hynix H2JTDG8UD2MBR 16 GB NAND Flash
Apple 338S1116 Cirrus Logic Audio Codec
Murata 339S0171 Broadcom BCM4334 WiFi Module
Fairchild BCHAH/FDMC Voltage Regulator / Reference
Fairchild BCHAH/FDMC Voltage Regulator / Reference
Elpida B4064B3MA-1D-F / 333S0638 512 MB LP DDR2 SDRAM
Elpida B4064B3MA-1D-F / 333S0638 512 MB LP DDR2 SDRAM
Texas Instruments CD3240B0 Touch Screen Line Driver
Broadcom BCM5973A1 Touch Screen Controller
Broadcom BCM5974 Touch Screen Controller
Omnivision OV290BA 5 Mp CMOS Image Sensor
Omnivision OV2C3B8E 1.2 Mp CMOS Image Sensor
STMicroelectronics AGD8 / 2234 Gyroscope
STMicroelectronics A233 / 33DH Accelerometer
Unknown 58874 / 59050 Unknown
Unknown 58874 / 59050 Unknown
Unknown 58874 / 59050 Unknown
Unknown 58874 / 59050 Unknown
Knowles S936 / 3250 Microphone