Laplace transform-based theoretical foundations and experimental validation: low-frequency supercapacitor circulation for efficiency improvements in linear regulators

Supercapacitor circulation techniques can be used to improve the end-to-end efficiency of linear regulators based on commercial low drop-out regulators (LDO). In this approach, one or more supercapacitors are used in series and parallel to the input of an LDO IC, and circulated at a very low frequency to increase the end-to-end efficiency by a multiplication factor compared with the efficiency of a linear regulator circuit with the same input-output voltages. This study presents the essential theory of supercapacitor circulation, together with analytical results and comparisons with experimental measurements from a practical 12-5 V implementation. The new technique achieved overall end-to-end efficiencies in the range of 70 to 80%, compared with the maximum theoretical efficiency of 42% for a 12-5 V linear regulator.