Sponsors: Texas Instruments

Group: Dong Ha

Harvesting small scale energy from otherwise wasted ambient energy sources has attracted immense interests for various battery-powered devices such as wireless sensor nodes, implant devices, and wireless light switches. Sources of energy harvesting include, but are not limited, to light, thermal gradient, vibration, air flow, and RF radiation, and the energy scavenged from ambient sources may be able to eliminate the battery to power up those devices perpetually.

Our research targets to harvest energy in sub-mW range, where commercial off-the-shelf chips cannot be applied. The fluctuation and intermittence of these ambient energy sources bring in challenging technical issues to harvest maximum energy. Maximum power point tracking (MPPT) dynamically matches the load impedance to the source impedance for maximum power transfer, and MPPT is commonly implemented with low-power microcontroller units (MCUs) for the energy level over mW range. However, MCUs are unsuitable for the sub-mW range energy harvesting due to relatively high power consumption. 

Currently, we investigate design of a power management IC, in which an MPPT algorithm is implemented with an analog circuit operating in the subthreshold region. The ultimate goal of our research is development of a power management IC targeting for multi-source energy harvesting, which can be applied for various small scale energy harvesting such as indoor light, wearable solar panels, body heat, human motion, and WiFi RF radiation.

The first test chip for an analog MPPT operating in the superthreshold region was designed and fabricated in CMOS 0.18 um. Its operation was tested successfully, and we will redesign the chip to operate in the subthreshold region and reduce power dissipation.

Course: Analog IC Track

Layout of our Power Management IC in CMOS 0.18 um
L measurement
Measurement Set up for our Power Management IC