Smaller A5 Chip From Tweaked Apple TV Contains Only One CPU Core, Revamped Analog Circuitry
For the past few days, we've been following the story of the smaller A5 chip found inside of the recently tweaked Apple TV, seeking to understand what changes Apple has made in order to shrink the chip to roughly half the size of the previous A5 chip.
Yesterday, experts at Chipworks determined that the new A5 was still being manufactured by Samsung using the same 32-nanometer process used for the previous version, indicating that Apple had undertaken significant design changes for the chip.
Chipworks now has a full image of the A5 die, revealing that this smaller A5 chip contains only a single-core ARM CPU. Apple has listed the Apple TV as having a single-core A5 since the third-generation model launched last year, but the previous design involved a dual-core chip with one core disabled, while the new design contains just the one active core. The new A5 does still contain the same dual-core GPU found in the previous version of the chip.
Chipworks' Dick James tells us, however, that there must be more to the story in order to achieve a nearly 50% size reduction, but the firm has yet to determine exactly what other changes are contributing to the smaller die size.
A separate observation of interest involves the analog circuitry included on the chip. This new A5 chip appears to take advantage of optimized analog components such as resistors, capacitors, and inductors, yielding a mixed signal chip that seems to be a rather significant technical achievement at the 32-nanometer process node.
My guess is that the analog sections have been re-designed, always a work in progress when we get this small, since analog circuitry does not shrink anywhere near as predictably as digital. And as Jim said earlier, we think this is now in a mixed-signal version of the 32-nm process that allows extra passive components such as resistors, capacitors, and inductors, that is much more suited to analog stuff.
It is still unclear exactly why Apple has elected to redesign the A5 for the Apple TV, as it has been assumed that the company's "hobby" does not generate enough shipment volume to warrant such an investment in and of itself. As a result, it is possible that Apple has plans to use this chip in other products, although the single-core nature of the CPU design will likely limit the range of devices for which it would be suitable.
Top Rated Comments
iWatch, obviously. :rolleyes:
All electronics circuits are analog. There is no such thing as a pure digital signal, it is just how its interpreted. All power and ground supplies are analog, all high-speed gigabit transmission paths are in +/- pairs and are much more analog than digital in how they are handled in board routing, impedance matching, etc.
Every circuit trace has capacitance and impedance, no voltage is stable enough to be 100% to an exact level at all times.
Hence, chips have analog function hardware... most often in the I/O drivers for transmit and receive logic on each pin, as well as for filtering power, powering on / off sections of the chip, and for Phased Lock Loops which are heavily used in microprocessors / SOCs.
Analog does not mean they are hooking up speakers or ancient technology directly to the chip. In-fact that would be a bad idea.
Actually, while you just stated it indirectly, that is a good point... there are multiple devices using the chip... what happens when there aren't? A5 is used on older designs. Maybe the single-core A5 Apple-TV is about to be the only thing left using the A5 processor in a few months. Why keep building a larger CPU than needed?
Why on earth would they worry about "shrinking" the size of the chip if they're simply going to put it in a TV.....
Well, a snowball's chance in hell is still a chance, I guess, so the answer is yes. :)