A 95.2% efficiency dual-path DC-DC step-up converter with continuous output current delivery and low voltage ripple

Abstract

DC-DC boost converters are widely used to increase the supply voltage in various applications, including LED drivers, energy harvesting, etc. [1-5]. The conventional boost converter (CBC) is shown in Fig. 27.5.1, where the switches S1 and S2 are turned on and off alternately at φ1 and φ2, respectively, and the inductor current (IL) is built up and delivered to the output. There are some critical issues in CBC because the output delivery current (IS) is not continuous. As a result, the IL can be much larger than the load current (ILOAD) as φ1 becomes longer. Since a bulky-size inductor having a low parasitic DC resistance (Rdcr) is not usable for mobile applications with a strictly limited space, this large IL results in significant conduction loss in the large RDCR of a small-size inductor. Another issue is that the discontinuous IS in φ2 causes large voltage ripple (AVOUT) at the output. Moreover, switching spike voltages can cause over-voltage stress on the loading block due to large di/dt of IS combined with parasitic inductances of the GND path.