The job listing, discovered by AppleInsider, describes the position as working within the "group at Apple that develops SOCs that will be used in Apple mobile devices," referring to the "system on a chip" devices designed by Apple and currently built by Samsung, including the A4 used inside iPhone 4 and the A5 powering the iPad 2.
A signal integrity engineer manages issues with sending electrical signals through chips, circuit boards, and interconnects between devices, preventing crosstalk, signal attenuation and power supply noise from overpowering data signals.
Apple asks for SI experience in working with both serial and parallel data links, naming DisplayPort (a digital serial link for video that the company currently uses only on its Mac desktops and notebooks) and LPDDR2 (a parallel data bus used by the type of fast RAM used inside the iPad 2's A5 chip).
This indicates that Apple is likely working to add support for the DisplayPort video standard to upcoming versions of its SOC, perhaps as soon as the delivery of the upcoming A6.
Apple currently only supports the older, analog composite VGA and digital parallel HDMI video standards for output from the iPhone 4, iPad and iPad 2. Adding the modern new digital serial DisplayPort link would enable future iOS devices to drive the new crop of displays that are beginning to appear, including Apple's own new Thunderbolt Display.
Thunderbolt, external displays and video input
There's no evidence to suggest that Apple will also incorporate SOC support for Thunderbolt's separate high speed data interconnect features, which the company added to its Mini DisplayPort jacks on new Macs released this year.
Thunderbolt pairs a direct, high speed link to the CPU (based on Intel's PCI Express standard) on the same cable as DisplayPort video, allowing modern Macs that support the new interconnect to drive one or more external displays while also connecting to high speed external storage devices and supporting bridge connections to alternative interfaces such as USB 2.0, Firewire, and Gigabit Ethernet.
However, the addition of DisplayPort support for iOS devices could make it easier to link future mobile devices to modern displays, as well as extend support for the bidirectional video feature in the latest versions of the video standard, making it possible to use an iPad as an external display for a MacBook Air, for example.
Currently, only the 27 inch iMac's DisplayPort supports the use of the system as an external display. Adding such a feature to iPads, particularly new ones with ultra high resolution displays, would add value to the product among mobile users and creative professionals.