A. Saiz-Vela

Power-Conditioning Circuitry for a Self-Powered System Based on Micro PZT Generators in a 0.13-

The concept and design of a power-conditioning circuit for an autonomous low-power system-in-package (SiP) is presented in this paper. The SiPs main power source is based on the use of micropiezoelectric generators. The electrical model of the power source, which has been obtained based on experimental measurements and implemented on Cadence Analog Artists Spectre simulation environment, is explained. The model has been used to simulate the power source with the power-conditioning electronics over the entire design process. Finally, the simulated and experimental results of the developed integrated power circuits, which are formed by a rectifier and a low-power bandgap reference voltage source to define the threshold voltage for the closed-loop regulation process, are also shown. These circuits have been designed using a commercial 0.13-mum technology from ST Microelectronics through the multi-projects circuits (CMP) techniques of informatics and microelectronics for integrated systems architecture (TIMA) service.

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A multiharvesting system conception focused on low-voltage (up to 2.5 V) and low-power applications is presented and validated as a point-of-view system. Using just this application-specified integrated circuit, with a total quiescent power consumption of 160 μW, the harvesting system is able to collect and manage energy from different power sources, such as solar light (indoor environment), vibration (low-voltage piezoelectric generators), and electromagnetic induction (operating with a carrier frequency of 13.56-MHz regulated band). The maximum total power harvested with the addition of the three harvesting sources is around 6.4 mW, for the operating conditions defined by a PZT at 7 m/s2 at 80 Hz, 1500 lx for a laboratory illumination, and 200 mW emitted by a base transmitter at 25-mm distance between coils. A broad and detailed description of all low-power-consumption circuits involved in the multiharvesting system is described, emphasizing their design for low-voltage and low-power applications.

Low-Voltage Low-Power Technology

A charge pump with a soft start-up control system and programmable regulated output is proposed in this paper for battery powered applications. The existing technique of a pulse skipping frequency regulator (PSFR) has been used to obtain a good efficiency over a wide range of loads. However, a new architecture for the PSFR with some improvements like a beta-independent behaviour and a programmable threshold voltage has been designed. The power-up control strategy that has been developed combines a linear and a switched charging sequence in order to avoid great current spikes at the start-up instant. Hence, the battery performance and the transistors of the charge pump are kept without any damage that could be produced by such initial current spikes. The result is a fully CMOS charge pump capable of generating a programmable and regulated output voltage from 3.3V up to 5.5V and deliver a maximum power of 100mW. This circuit has been implemented in 0.7 /spl mu/ I/sup 2/T technology from AMI semiconductor.

A Multiharvested Self-Powered System in a Low-Voltage Low-Power Technology

A power efficiency study of a full-custom two-phase voltage doubler based switched-capacitor DC-DC step-up converter IC is presented in this paper. The study is focused on the global IC power consumption but also on the particular power consumption of the different circuits that form the whole design because besides including the voltage doubler architecture, additional circuits like power-up circuits, low-power level shifters, digital control logic and a pulse skipping frequency regulator have been included in the final IC design for having a robust, efficient and fully working step-up converter. Two switching modes have been implemented in the designed IC: normal mode and pulse skipping mode. Simulated results of the ICs power consumption show a remarkable efficiency improvement, especially at lighter loads, when pulse skipping switching mode is applied. The proposed design has been implemented using the high-voltage I2T100 0.7mu technology from AMI semiconductor and has been tested successfully

An electron mobility independent pulse skipping regulator for a programmable CMOS charge pump

Two low-power high-voltage non-overlapping clock generators are presented in this paper. One of them is based on the use of delay RC cells whereas the other one is based on the counting process of the output pulses generated by a digitally controlled oscillator (DCO). The DCO-based solution is more complex but more flexible than the RC-based configuration since it allows a dynamically programmable control of the non- overlapping time between the clock signals that can not be achieved with the RC-based approach. Simulated results of both architectures show that our proposed circuits lead to lower power consumption levels in comparison with conventional solutions. Experimental results of one of these architectures are also presented in order to show the feasibility of our designs which have been implemented using the 0.7mu I2T BCD technology from AMI semiconductor.

Pulse Skipping Switching mode: a case study of Efficiency Improvement on a switched-capacitor DC-DC step-up converter IC

A biopotentiostat amplifier, for in-vivo applications, has been designed using a low-voltage low-power technology of 0.13µm@1.2V. The purpose of the designed bio-amplifier is oriented to sense the capacitive variations of electrochemical biosensor experiments at low frequencies. The designed amplifier seeks to function with a very small power consumption and occupies a very small area, compared with other designs, looking for an in-vivo application. It occupies an area of 327µm × 260µm, and has an average power consumption of 51.2 µW. The performance of the bio-amplifier has been simulated and experimentally validated.

Low-Power High-Voltage Non-overlapping Clock Generators for Switched-Capacitor step-up DC-DC Converters

This paper presents the architecture of a novel implementation of an integrated self-powered system based on piezoelectric vibrations in a 0.13µm technology. The electromechanical transduction is performed by using a low-cost commercial piezoelectric, working at low frequencies, with voltages up to 2.5V. The system is conceived as a System In a Package (SiP). The full integrated system is adapted to work with low-voltage and low-power conditions. The full custom power management circuit is used to charge a storage capacitor (super capacitor), from which the stored energy will be used to power, by controlled cycles of discharge operation of a very low power wireless sensor node that could be used in heavy machinery monitoring. Each circuitry block of the power management circuitry is presented and discussed. The simulated studies are fully validated by experimental tests. The experimental consumption of the power management unit is 67µW, approach to the theoretical expected value of 60µW.

A low power CMOS biopotentiostat in a low-voltage 0.13 µm digital technology

Nowadays, there is an important interest in smart wireless sensors. A key point in their development is the way they are powered. Piezoelectric energy conversion can be used for such purpose. In this paper, a novel architecture that combines in a single integrated circuit the power conditioning circuitry needed to use piezoelectric energy conversion and an embedded temperature sensor is presented.

A 60 µW low-power low-voltage power management unit for a self-powered system based on low-cost piezoelectric powering generators

A self powered microsystem (SPMS) is based on a micro power generator, that converts the available energy to an electrical form. In the architecture of the SPMS systems there are two main electrical circuits: an AC/DC converter and a DC/DC converter. This paper presents the performance of three AC/DC rectifiers designed in 0.13 μm technology, in the frame of low voltage and low power applications, which are a typical rectifier based on PN junctions, and two synchronous rectifiers. The performance of each rectifier is verified at this stage by simulation results in terms of efficiency. Furthermore, it is presented the application of the synchronous boosted rectifier, the best one, with an inductorless DC/DC charge-pump regulator, that will define the SPMS system

SiP power management unit with embedded temperature sensor powered by piezoelectric vibration energy harvesting

The paper presents a power conditioning circuit (PCC) for an autonomous low power system in package (SiP) based on harvesting energy from vibrations. This self-powered system would be placed in indoor environments. The electromechanical transduction is performed using a low-cost commercial piezoelectric product, working at low frequencies and with voltages up to 2.5 V. The final designed IC has been tested and described in detail.