Ultra-low power management and voltage regulation

Ultra-low power management and voltage regulation
Scientific Highlights 2016
Ultra-low power management and voltage regulation
Keywords : Energy harvesting; Switched-capacitor converters; Linear regulators; IoT.
David Bol, Pierre-Antoine Haddad, Khoi Nguyen, Guerric de Streel, Denis Flandre
• a multi-mode switched-cap DC/DC converter for a wide output
power range that was successfully prototyped in 28nm FDSOI
CMOS [7] in collaboration with ST Micro (Crolles, France).
Abstract – For a massive yet sustainable Internet-of-Things,
ultra-low power management and voltage regulation are required
to operate the nodes on ambient energy harvesting (EH) while
delivering the required supply voltages to the sensing, computing and communication blocks. Latest related results obtained
in the electronic circuits and systems (ECS) group include indoor/outdoor solar EH power management units licensed to
and industrialized by e-peas semiconductors, RF-harvesting rectifiers, a reconfigurable switched-capacitor converter with a wide
load power range in collaboration with ST Microelectronics, a
voltage reference with the record 0.2V minimum and an ultralow-quiescent current linear regulator with most of them included in a 3-mm2 solar-powered video analysis System-on-Chip
(SoC) codenamed SunPixer.
Figure 1: SunPixer SoC in 65nm CMOS.
The connection of our daily life’s objects to the cloud according
to the Internet-of-Things (IoT) vision is about to revolutionize the
way we live. To enable this revolution, a massive deployment of
sensor nodes is required with predictions announcing up to trillions of
these nodes. Such a massive deployment is not environmentally and
economically sustainable with current battery-operated technologies.
Indeed, to avoid the cost and the ecotoxicity of battery replacement, the IoT nodes need to operate by harvesting the ambient
energy present in various forms: solar, thermoelectric, piezoelectric
or electromagnetic RF [1].
Figure 2: Layout of ADELE LDO regulator in 0.13µm CMOS.
Commercial energy-harvesting power management units (EHPMU) fail to meet the demand for autonomous startup (cold start)
when the energy storage is empty. A first EH-PMU for micro PV
cells based on an inductive boost converter was designed with the
specific target to provide robust cold start functionality and maximumpower-point tracking while allowing to supply a wide range of offthe-shelf sensing, computing and communication components. It
was licensed to e-peas semiconductors spin-off which successfully
prototyped and industrialized it under its AEM product line [2]. A
second EH-PMU for micro PV cells was designed based on a single
bidirectional multi-gain/multi-mode switched-capacitor converter for
direct harvester/load connection and on-chip integration in 65nm
CMOS without external inductor [3]. It was integrated within the
SunPixer SoC (Fig. 1), which is a 3-mm2 solar-powered video analysis
Next research in this field is focused on multi-source EH-PMUs
and all-synthesized PMUs using only digital standard cells. A prototype all-synthesized low-dropout (LDO) regulator codenamed ADELE
(Fig. 2) was designed. The chip is currently under prototyping.
[1] D. Bol, G. de Streel and D. Flandre, “Can We Connect Trillions of IoT
Sensors in a Sustainable Way? A Technology/Circuit Perspective”, in
IEEE S3S Conf., pp. 49-50, 2015.
[2] http://e-peas.com/products/aem10940/
[3] D. Bol, E.H. Boufouss, D. Flandre and J. De Vos, “A 0.48mm2 5µW-
10mW Indoor/Outdoor PV Energy-Harvesting Management Unit in
RF electromagnetic energy from wireless communication siga 65nm SoC based on a Single Bidirectional Multi-Gain/Multi-Mode
nals is another interesting energy source in densely populated zones.
Switched-Cap Converter with Supercap Storage”, in Proc. European
Front-end interfaces for RF EH-PMU must include an AC/DC conSolid-State Circ. Conf., pp. 241-244, 2015
verter typically implemented by a rectifier. An optimization method
[4] P.-A. Haddad, G. Gosset, J.-P. Raskin and D. Flandre, “Automated
for rectifiers has been developed and validated on the design of a
design of a 13.56 MHz 19 µW Passive Rectifier with 72% Efficiency
13.56-MHz rectifiers [4] using UCL-patented ULP diodes on simunder 10 µA load”, in IEEE J. Solid-State Circuits, 2016
ple Greinacher architecture and with more complex architectures
[5] G. de Streel, J. De Vos and D. Bol, “A ∆VT 0.2V to 1V 0.01mm2
(cross-coupled, differential drive).
9.7nW Voltage Reference in 65nm LP/GP CMOS”, in Proc. IEEE
SOI-3D-Subthreshold Microelectronics Conf., 2 p., 2015.
From the system supply voltage generated by the EH-PMU, the
specific ultra-low-voltage (ULV) load supplies need to be generated
and regulated with circuits including:
[6] G. de Streel, J. De Vos, D. Flandre and D. Bol, “A 65nm 1V to 0.5V
linear regulator with ultra-low quiescent current for mixed-signal ULV
SoCs”, in Proc. IEEE FTFC Conference, 4 p., 2014.
• the first voltage reference circuit starting at a 0.2-V supply
[7] S. Clerc et al, “A 0.33V/-40˚C Process/Temperature Closed-Loop
voltage that was successfully prototyped in 65nm CMOS [5],
Compensation SoC Embedding All-Digital Clock Multiplier and DC-DC
• an ultra-low-quiescient current linear regulator with a highConverter Exploiting FDSOI 28nm Back-Gate Biasing”, in Proc. IEEE
Int. Solid-State Circuits Conf., pp. 150-151, 2015.
dropout (HDO) architecture that was successfully prototyped
in 65nm CMOS [6],
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