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

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 S<inf>1</inf> and S<inf>2</inf> are turned on and off alternately at φ<inf>1</inf> and φ<inf>2</inf>, respectively, and the inductor current (I<inf>L</inf>) is built up and delivered to the output. There are some critical issues in CBC because the output delivery current (I<inf>S</inf>) is not continuous. As a result, the I<inf>L</inf> can be much larger than the load current (I<inf>LOAD</inf>) as φ<inf>1</inf> becomes longer. Since a bulky-size inductor having a low parasitic DC resistance (R<inf>dcr</inf>) is not usable for mobile applications with a strictly limited space, this large I<inf>L</inf> results in significant conduction loss in the large R<inf>DCR</inf> of a small-size inductor. Another issue is that the discontinuous I<inf>S</inf> in φ<inf>2</inf> causes large voltage ripple (AV<inf>OUT</inf>) at the output. Moreover, switching spike voltages can cause over-voltage stress on the loading block due to large di/dt of I<inf>S</inf> combined with parasitic inductances of the GND path.