A KGI Securities analyst issued a note this weekend saying that while the iPhone 6 is still excepted to debut this fall, a larger 5.5-inch device won't be introduced until sometime in 2015.

This means just the 4.7-inch iPhone will debut later on this year, said KGI Securities analyst Ming-Chi Kuo, according to AppleInsider.com.

Apple is already facing production issue on the 4.7-inch model related to the new technology for the phone's in-cell touch panel, along with color unevenness on the redesigned iPhone metal casing.

The issues are worse with the 5.5-inch model, according to Kuo.

"These problems will likely be even more complicated with a larger size," Kuo said.

Specifically, Kuo said the new in-cell touch panels might have issues related to touch sensitivity on the edges of the panel as displays become larger in size. This would make the 5.5-inch model a much harder technical feat for Apple to achieve, according to Kuo.

The analyst also doesn't expect that a new scratch resistant 5.5-inch sapphire front panel will "easily pass the drop test near term." The issue could cause also cause delays.

Kuo said the "most conservative scenario" is that Apple delays the 5.5-inch iPhone 6 until 2015. If this were to occur, the 4.7-inch model, along with the iPhone 5S and iPhone 5C, will be expected to increase Apple sales during the holiday quarter.

The earliest Kuo sees the 5.5-inch device being released is mid-to late-November, which would be two months after the 4.7-inch is expected to debut.

Apple is expected to announce its iPhone 6 the first or second week of September, before releasing it later on in the month.

Usually Apple waits to release its new smartphone on a Friday, which means the iPhone 6 could become available for purchase on September 12th, 19th, or 26th.

Both devices will most likely come with a scratch-free sapphire crystal glass screen, according to MacRumors. The devices are expected to be powered by a 20-nanometer A8 chip and come with an 8MP camera with a number of new upgrades, like flash and Optical Image Stabilization.

Both devices are expected to run on iOS 8.

The smaller iPhone is expected to come with a 1920x1080p (440ppi) resolution, while the larger device may feature a 2272×1280 (510ppi) resolution, according to multiple media outlets.

A new iOS 8 operating system that the next iPhone will utilize debuted at Apple's 2014 Worldwide Developers Conference earlier this year.

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