A novel interface circuit topology with power management is presented for ultra-low voltage DC-DC step-up conversion. The proposed 90 nm CMOS circuit avoids off-chip components or non-standards processes, and is suitable for ultra-low voltage system-on-chip applications. Comparative analysis was performed with a commercial low voltage DC-DC converter to identify the relative advantages and disadvantages of the integrated approach. The circuit can be started up from input voltage as low as 0.2V based on the simulations, and generates 2.3V with 12% of maximum efficiency.