A Self-Resonant Boost Converter IC Supporting Multimode Operation for Wide-Range TEG Energy Harvesting in 28-nm CMOS

This article presents a self-resonant boost converter integrated circuit (IC) for wide-range source tracking of a thermoelectric generator (TEG). For efficient energy harvesting, a boost converter supporting multimode operation, including discontinuous conduction mode, critical conduction mode, and continuous conduction mode, is desirable. However, tracking a wide range of sources using conventional maximum power point tracking (MPPT), which is based on a fixed-frequency single-mode, is challenging. As a solution, this article proposes embedding the MPPT controller inside a self-resonant oscillator (SRO), which is inherently available inside the boost converter. The MPPT controller, which manages the on-time of the low-side switch, operates within the loop dynamics of the SRO. This approach achieves TEG source impedance (R_S) tracking over a 20× operating range of 7-150 Ω. A maximum output voltage tracking (MOVT) controller is proposed for the on-time control of the high-side switch under multimode operation. The proposed SRO and MPPT controller consume 44.9 and 454.1 nW, respectively, at a source voltage (V_S) of 150 mV. The MOVT controller consumes 122.4 nW. The total power consumption of the boost converter is 777.8 nW. The converter IC has been fabricated in a 28-nm low-power (LP) 1-poly 11-metal CMOS process. Measured results show the converter achieves tracking efficiency >90% over a wide R_S range of 10-103 Ω. The measured peak end-to-end efficiency is 89.4% at V_S = 200 mV and R_S = 7 ω.