Buck and boost switched capacitor gain stage with optional shared rest state

Abstract

A structure and process are provided for converting DC-DC voltages, which allows both buck and boost conversion utilizing a single switched capacitor array. In one embodiment of this invention, the switched capacitor array comprises multiple gain blocks, where the gain blocks are identical and stacked upon each other. The switches and capacitors are configured so that various combinations of series and parallel capacitor connections are possible, and thus both buck and boost conversions are attainable with one switched capacitor array. Other embodiments of the present invention use multiple gain blocks, configured such that the capacitor in each gain block can be connected to ground. As a result, a single charge state for a range of desired gains can be configured for use with a shared or common rest state, i.e., a capacitor configuration which is the same regardless of the desired gain. In the charge state, selected capacitors are configured in series for the desired gain setting, while in the shared rest state, all the capacitors are configured in parallel from the output to the input. Because a shared rest state is used, the correct charge is always transferred at the desired gain with a single switched capacitor array.