A Circuit for Reducing the Reverse Current in DCM DC-DC Converters

We propose a circuit that performs a reverse-current reduction (RCR) in switched-mode dc-dc converters. The reverse current is undesirable since it causes power losses when the converter is operating in the Discontinuous Conduction Mode (light-load currents). Conventional designs for reducing the reverse current often require an accurate comparator or complex circuitries to sense and reduce the reverse current. The RCR circuit is simple and relaxes the accuracy requirements for the comparator since the RCR circuit senses the reverse current differentially. Power transistors operating at 3.3 V input, 2 V output, 23 mA output (DCM operation), 5 MHz switching frequency, and combined with the RCR circuit are simulated using a 0.18 μm CMOS process. The RCR circuit reduces the reverse current of the power transistors by 83% and that translates to an improvement of the power efficiency by 16% when compared to that achieved by the same power transistors but with a conventional reverse-current reduction circuit.