PCB electronic subsystems refer to a portion of an electronic system that is implemented on a single printed circuit board. A PCB is a flat board made of non-conductive material, like fiberglass, with conductive pathways etched or printed onto its surface. These pathways, called traces, connect various electronic components such as resistors, capacitors, integrated circuits (ICs), and connectors.

An electronic subsystem within a PCB context refers to a functional block or module of an overall electronic system that is implemented on a single PCB. Electronic systems can be quite complex and consist of multiple interconnected subsystems, each performing a specific task. These subsystems can be designed and assembled onto separate PCBs to modularize the system and make it more manageable during design, manufacturing, and maintenance.

For example, consider a smartphone as an electronic system. It contains several subsystems, such as the central processing unit (CPU), display driver, power management, audio processing, wireless communication, and more. Each of these subsystems can be designed on separate PCBs and then integrated to form the complete smartphone electronic system.

Designing electronic subsystems on PCBs allows for efficient layout, compact packaging, and better organization of components and interconnections. It also facilitates easier debugging, testing, and upgrading individual system parts.