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Processors for next generation mobile devices will need to operate across a wide supply voltage range in order to support both high performance and high power efficiency modes of operation. However, the effects of local transistor threshold (VT) variation, already a significant issue in today's advanced process technologies, and further exacerbated at low voltages, complicate the task of designing reliable, manufacturable systems for ultra-low voltage operation. In this paper, we describe a 4-issue VLIW DSP system-on-chip (SoC), which operates at voltages from 1.0 V down to 0.6 V. The SoC was implemented in 28 nm CMOS, using a cell library and SRAMs optimized for both high-speed and low-voltage operating points. A new statistical static timing analysis (SSTA) methodology was also used on this design, in order to more accurately model the effects of local VT variation and achieve a reliable design with minimal pessimism.