This paper analyzes the operation of a high gain non-isolated boost converter that is a combination of interleaved boost and switched capacitor configuration in critical conduction mode. The converter is able to provide high gain while reducing the current and voltage stresses on semiconductor devices. The converter operation can be divided into different zones based on the duty ratio of operation. In Zone I, which corresponds to the highest gain, the converter possesses inherent current sharing properties among different phases. The inductance value and size are reduced significantly due to interleaving. To further reduce the size, the converter is operated in critical conduction mode. This also results in increased efficiency as turn-on losses of the MOSFETs are zero. A 2kW silicon MOSFET based 4-phase prototype with 42V-52V input and 850V output and operating at varying frequency to maintain critical conduction mode operation at various power levels has been developed to validate the proposed scheme. The total inductor volume is reduced by 48% and the efficiency improves by 0.9% at rated load in CRM operation with the peak efficiency of 97.2% achieved at 1200W.