This paper presents a multicell cascaded quasi-square-wave (MCQSW) boost converter for non-isolated DC-DC applications with high voltage conversion ratios. The MCQSW boost converter is designedto operate at high frequencies and can achieve zero voltage switching (ZVS), soft charging, currentsharing, and automatic voltage balancing. In the MCQSW converter, many boost cells are connected inparallel in series to distribute the high input current; multiple output capacitors are stacked in series to achieve high output voltage. The multicell parallel-input series-output configuration cansignificantly extend the voltage conversion ratios of the traditional QSW boost converters while maintaining low power conversion stress and enable low input current ripple due to interleaving. The high-frequency ZVS operation is enabled by an analogy control circuitry which can operate up to a few MHz. A 700 kHz to 5 MHz, 15 V-180 V (1:12 conversion ratio), 250 W MCQSW converter was built to validate the effectiveness of the MCQSW converter achieving a peak efficiency of 91%.