The iPhone 6s lineup might soon get a smaller sibling.

KGI Securities analyst Ming-Chi Kuo predicted that Apple will launch a new, 4-inch iPhone in the first half of 2016, according to a research note obtained by Macrumors. Kuo said there is still consumer demand for smaller phones, and Apple will attempt to scratch that itch with a device that looks like the company's iPhone 5s, which launched two years ago.

Kuo suggests the device will come with "metal casings," and run Apple's A9 chip and iOS 9. Given that it would be smaller and cheaper, however, the smartphone would likely not come with support for Apple's 3D Touch feature.

If Apple decides to launch a 4-inch iPhone—a rumor that has been swirling for several months— the device would complement the larger devices the company already sells. Starting with its iPhone 6 line, Apple shipped smartphones with 4.7- and 5.5-inch screens. The 4-inch iPhone 5s is still part of Apple's iPhone lineup, but it runs the aging A7 chip.

In recent years, Apple has released new iPhones in the fall, and Kuo predicted the iPhone 7 would arrive then with 3GB of RAM for the iPhone 7 Plus.