Power Management

System operation from harvested energy is a much-desired feature to enable no maintenance,  perpetual operation. However, the primary challenge of harvesting energy from the ambient environment is the low output power level from the harvester. At lower input voltage levels, the efficiencies of the energy harvesting circuits decrease because of the high conduction loss in the low-side switch of the boost converter. Furthermore, the standby power consumption or quiescent current required to bias the analog circuits inside the boost converter also has to be at a very low power level to reduce the overhead and enable harvesting even at nanowatt power levels. This requires ultra-low power voltage references, current references, comparators, and sub-threshold digital circuits for energy harvesters, which in turn has driven the need for new circuit architectures for many of the so-called conventional analog circuits such as bandgap references, oscillators, etc. In summary, energy harvesting at low power levels requires methods to improve conversion efficiency as well as operation from ultra-low power biasing methods for analog and digital control circuits. We have developed highest efficiency as well as harvesting from the lowest possible voltage of 10 mV. We achieved higher efficiency and lowest input voltage through a novel inductor current control circuit and offset compensation techniques.  The Figure shows the architecture and the measurement of the boost converter.

Related Publication

  • Z. Xu, N. Mirchandani, M. A. A. Ibrahim, M. Onabajo, and A. Shrivastava , “A High Efficiency DC-DC Converter Architecture with Adjustable Switching Frequency to Suppress Noise Injection in RF Receiver Front-Ends”,  IEEE International Symposium on Circuits and Systems (ISCAS), May-2020, Seville, Spain. (accepted for publication)
  • S. Tewari and A. Shrivastava , “Ultra-low Power Charge-Pump-Based Bandgap References”, in Hybrid ADCs, Smart Sensors for the IoT, and Sub-1V and Advanced Node Analog Circuit Design (Springer, 2018). pdf 
  • N. Mirchandani and A. Shrivastava , “High Stability Gain Structure and Filter Realization with less than 50 ppm/oC Temperature Variation with Ultra-low Power Consumption using Switched-capacitor and Sub-threshold Biasing”,  IEEE International Symposium on Circuits and Systems (ISCAS), May-2018, Florence, Italy. pdf
  • M. A. A. Ibrahim, N. Mirchandani, N. Shafiee, M. Onabajo and A. Shrivastava, “Study of Performance Impact from Powering RF Receiver Front-End Circuits with a DC-DC Converter”,  IEEE International Symposium on Circuits and Systems (ISCAS), May-2018, Florence, Italy. pdf
  • A. Shrivastava, N. E. Roberts, O. U. Khan, D. D. Wentzloff, and B. H. Calhoun, A 10mV-Input Boost Converter with Inductor Peak Current Control and Zero Detection for Thermoelectric and Solar Energy Harvesting with 220mV Cold-Start and -14.5dBm, 915MHz RF Kick-Start“, IEEE Journal of Solid-State Circuits (JSSC), vol. 50, issue 8, pp. 1820-1832, 08/2015. pdf
  • A. Shrivastava, D. D. Wentzloff, and B. H. Calhoun, “A 10mV-Input Boost Converter with Inductor Peak Current Control and Zero Detection for Thermoelectric Energy Harvesting IEEE Custom Integrated Circuits Conference (CICC), September 2014. pdf
  • A. Shrivastava, Y. K. Ramadass, S. Khanna, S. Bartling, and B. H. Calhoun, “A 1.2µW SIMO Energy Harvesting and Power Management Unit with Constant Peak Inductor Current Control Achieving 84-92% Efficiency Across Wide Input and Output Voltages,” IEEE Symposium on VLSI Circuits (VLSI Symp.) June 2014. pdf
  • A. Shrivastava, B. H. Calhoun, “A DC-DC Converter Efficiency Model for System Level Analysis in Ultra Low Power ApplicationsJournal of Low Power Electronics and Applications (JLPEA), Vol. 3, No. 3, June 2013, pgs 215-232. pdf