Session 23 – TAPA II

Power Management Circuits

Friday, June 15, 3:25 p.m.

Chairpersons: H. Bergveld, NXP Semiconductors

H. Nakamoto, Fujitsu Labs, Ltd.

23.1 - 3:25 p.m.

A 0.45-V Input On-Chip Gate Boosted (OGB) Buck Converter in 40-nm CMOS with More Than 90% Efficiency in Load Range from 2µW to 50µW, X. Zhang, P.-H. Chen, Y. Ryu*, K. Ishida, Y. Okuma*, K. Watanabe*, T. Sakurai, M. Takamiya, University of Tokyo, *STARC

A 0.45-V input, 0.4-V output on-chip gate boosted (OGB) buck converter with clock gated digital PWM controller in 40-nm CMOS achieved the highest efficiency to date with the output power less than 40uW. A linear delay trimming by a logarithmic stress voltage (LSV) scheme to compensate for the die-to-die delay variations of a delay line in the PWM controller with good controllability is also proposed.

23.2 - 3:50 p.m.

A Fully Electrical Startup Batteryless Boost Converter with 50mV Input Voltage for Thermoelectric Energy Harvesting, H.-Y. Tang, P.-S. Weng, P.-C. Ku, L.-H. Lu, National Taiwan University

A fully electrical startup boost converter is presented in this paper. With a three-stage stepping-up architecture, the proposed circuit is capable of performing thermoelectric energy harvesting at an input voltage as low as 50 mV. Due to the zero-current-switching (ZCS) operation of the boost converter and automatic shutdown of the low-voltage starter and the auxiliary converter, conversion efficiency up to 73% is demonstrated. The boost converter does not require bulky transformers or mechanical switches for kick-start, making it very attractive for body area sensor network applications.

23.3 - 4:15 p.m.

Integrated All-silicon Thin-film Power Electronics on Flexible Sheets For Ubiquitous Wireless Charging Stations based on Solar-energy Harvesting, L. Huang, W. Rieutort-Louis, Y. Hu, J. Sanz-Robinson, S. Wagner, J.C. Sturm, N. Verma, Princeton University

With the explosion in the number of battery-powered portable devices, ubiquitous powering stations that exploit energy harvesting can provide an extremely compelling means of charging. We present a system on a flexible sheet that, for the first time, integrates the power electronics using the same thin-film amorphous-silicon (a-Si) technology as that used for established flexible photovoltaics. This demonstrates a key step towards future large-area flexible sheets which could cover everyday objects, to convert them into wireless charging stations. In this work, we combine the thin-film circuits with flexible solar cells to provide embedded power inversion, harvester control, and power amplification. This converts DC outputs from the solar modules to AC power for wireless device charging through patterned capacitive antennas. With 0.5-2nF transfer antennas and solar modules of 100cm2, the system provides 47-120μW of power at 11-22% overall power-transfer efficiency under indoor lighting.

23.4 - 4:40 p.m.

A 2.98nW Bandgap Voltage Reference Using a Self-Tuning Low Leakage Sample and Hold, Y.-P. Chen, M.Fojtik, D. Blaauw, D. Sylvester, University of Michigan

A novel low power voltage reference using a sample and hold circuit with self-calibrating duty cycle and leakage compensation is presented. Implemented in 180nm CMOS, it shows a temperature coefficient of 24.7ppm/°C and power consumption of 2.98nW which marks a 251× power improvement over the best prior bandgap reference.

23.5 - 5:05 p.m.

A 635pW Battery Voltage Supervisory Circuit for Miniature Sensor Nodes, I. Lee, S. Bang, Y. Lee, Y. Kim, G. Kim, D. Sylvester, D. Blaauw, University of Michigan

We propose a low power battery voltage supervisory circuit for micro-scale sensor systems that provides power-on reset, brown-out detection, and recovery detection to prevent malfunction and battery damage. Ultra-low power is achieved using a 57pA, fast stabilizing two-stage voltage reference and an 81pA leakage-based oscillator and clocked comparator. The supervisor was fabricated in 180nm CMOS and integrated with a complete 1 mm3 sensor system. It consumes 635pW at 3.6V supply voltage, which is an 850× reduction over the best prior work.