Design Considerations for Switched-Mode Power Supplies with Capacitive Coupling

Switched-mode power supplies (SMPS) typically utilize optical couplings via optocouplers or inductive couplings with pulse transformers to close the feedback loop. To enhance the performance of SMPS and reduce production costs, this paper explores design considerations by replacing the inductive and optical couplings with a capacitive coupling. The capacitive coupling is formed from the PCB wiring of the power supply and its incorporated copper layers. The performance of the modified SMPS is evaluated through computer simulations, followed by the construction of a physical prototype based on the proposed design and calculations. The presented solution offers several advantages, such as: it improves temperature stability, leading to less variation of key parameters due to temperature fluctuations or it lowers manufacturing costs by eliminating the need for optocouplers or transformer cores in favor of a capacitive coupling circuit.