This paper presents a boost converter for thermo-electric energy harvesting with photovoltaic (PV)-assisted startup. The converter employs a new two-phase startup architecture and the PV cell is used in the first phase to provide an initial high voltage for startup. This high voltage drives the boost converter to charge a startup capacitor, which powers the main control block to continue self-startup in phase 2. The proposed system is designed and simulated in a $0.18\mu{\mathrm{m}}$ BCD process. The simulations show successful cold-start from 10 mV thermoelectric voltage. In addition, maximum power point tracking and zero current switching techniques are adopted in the system to achieve 91% peak efficiency. The proposed system can finish the cold-start within 250 ms.@en