A fully integrated self-oscillating switched-capacitor DC-DC converter for near-threshold loads

We introduce a fully integrated step-down self-oscillating switched-capacitor DC-DC converter that delivers near-threshold (NT) output voltages. The converter is built in 28 nm UTBB FD-SOI and occupies 0.0104 mm
²
. Back-gate biasing is utilized to increase the load power range. Measurements show a peak efficiency of 87%, self start-up capability, and a minimum efficiency of 75% for 79 nW to 200 μW (ideal) loads. Measurements with an off-chip NT processor load also show high efficiency. The converter's large load power range and high efficiency are a good fit for energy-constrained NT processors.