This article presents a 10mV-startup-voltage thermoelectric energy harvesting system, assisted by a piezoelectric generator (PEG) as a cold starter. It exploits the fact that when a thermoelectric energy harvesting system is implemented in a place where kinetic energy is also present, the PEG starter can provide a clock signal to start the system. Thanks to the high output impedance of the PEG, the generated clock voltage can easily go over several hundreds of mV, which can be used to drive the boost converter to harvest thermoelectric energy even at an extremely low thermoelectric generator (TEG) voltage. The proposed system was fabricated in a 180-nm BCD process. The measurement results show that the TEG system can start up from the cold state with a TEG voltage as low as 10 mV while maintaining a 63.9% efficiency. The peak power conversion efficiency reaches 83.7% when the TEG voltage is 55 mV.@en

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

An ultra-low-startup-voltage thermoelectric energy harvesting system assisted by a piezoelectric generator (PEG) is presented in this paper. When the energy harvesting system is implemented in a place where there is mechanical vibration, the associated PEG can generate a stable clock signal and drive the boost converter to start from the cold state even at extremely low thermoelectric generator (TEG) voltage. The proposed system is designed and simulated in a 180-nm BCD process. The simulations show that the proposed system can start the TEG system from the cold state from as low as 10 mV of TEG voltage while keeping a 63.9% efficiency. The peak power conversion efficiency is achieved at 74.9% when the TEG voltage is 50 mV.@en