| Description |
The purpose of this thesis was to determine if low-power switching power supplies can be made on-chip using integrated components. Integrated switching supplies are an emerging field that has followed the rise of systems-on-chip devices - especially in the biomedical field. Switching supply theory and implementation were examined systematically to determine the feasibility of such switching supplies. Classical switching power supply theory was presented first, including fundamental principles of operation and essential analysis techniques. Due to the unique constraints placed on integrated power supplies as a result of the small component size, the classical treatment had to be updated and modified. The result was a new methodology for calculating ripple current and voltage, circuit losses, and efficiency of switching supplies in both continuous and discontinuous conduction modes. Integrated and micro-scale switching supply components were then examined. Most importantly, the design of integrated inductors was discussed. Double-layer coils were found to be the best choice for integrated inductors with a small number of coils as they offered four times the inductance and only twice the resistance of similar single-layer coils. Six boards were tested using a variety of loads with manual switching cycle control. The test boards effectively modeled the behavior of integrated supplies and confirmed predictions about power loss and transfer. Using the test results and the equations previously derived, three test cases were simulated. The results were efficiencies of 75.16%, 75.09%, and 75.10% using 2 and 5 turn double spirals, and an external 120 nH coil, respectively. With these results, it should be possible to build integrated switching power supplies that meet or exceed the efficiency of linear supplies. |
