What does a daughterboard connect to in a smartphone?

A daughterboard in a smartphone typically connects to the motherboard, which is the main printed circuit board (PCB) containing the essential components of the device. The connection between the daughterboard and the motherboard allows it to serve as an extension that can provide additional circuitry, features, or components that are not housed on the motherboard itself.

For example, a daughterboard might include chips for functionalities like power management, or wireless communication capabilities, thus enhancing the smartphone's performance and features. This modular design allows for efficient use of space within the device, as the primary functions can be managed by the motherboard while supporting functionalities are handled by the daughterboard.

Other options, like connecting to the battery, the screen, or the audio jack, do not accurately reflect the primary function of a daughterboard. While these components are indeed crucial to the smartphone's operation, they are not the main connection point for a daughterboard, which is specifically designed to augment the capabilities provided by the motherboard.