P. Miribel-Catala

An integrated digital PFM DC-DC boost converter for a power management application: a RGB backlight LED system driver

In this paper is presented a system that has been designed in the frame of a co-operation between the ON Semiconductor Microelectronics Company, at its Toulouse (France) Design Centre and the Electronics Department of the University of Barcelona (SIC Group). The system that has been designed is a high efficiency boost converter to supply and drive multicolour LEDs (light emitting diodes). The paper presents the switching power DC/DC boost converter performances, based on a current peak PFM (pulse frequency modulation) system, with the objective to design this system for in low-voltage portable applications. The DC/DC converter is able to source an output current up to 300 mA, and it presents good performances for very low load conditions (100 /spl mu/A), for an input battery of 3.6 V (nominal value). It needs an external inductor of 10 /spl mu/H. From an external micro-controller the output voltage value can be programmed to either two values of 4 V or 5 V. LEDs brightness is controlled by a digital pulse width modulation (PWM) procedure.

CMOS front-end architecture for In-Vivo biomedical implantable devices

An integrated front-end architecture for in-vivo detection is presented. The system is conceived to be implanted under the human skin. The powering and communication between this device and an external primary transmitter are based on an inductive link. The presented architecture is oriented to two different approaches, defining a true/false alarm system, based on amperometric or impedance biosensors. The particular case of the amperometric sensor is used to validate the architecture in terms of different integrated modules fabricated in a 0.13 ¿m technology. A potentiostat amplifier has been integrated to control an amperometric biosensor as well as a current sensing method based on a transimpedance amplifier is used to measure the current. It is also introduced the electronics designed for the bio-impedance case.

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

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

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

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.

Toward an Anemia Early Detection Device Based on 50-μL Whole Blood Sample

A first approach to a portable and compact device for point-of-care (PoC) early instantaneous detection of anemia is described. This device works directly with whole blood samples relying on hematocrit analysis by means of impedance analysis. This device consists of a custom electronic instrumentation, postprocessing software and plug-and-play disposable sensor. The designed electronics are connected to a remote computer, which allows control of the instrumentation and results displaying with a user friendly software panel. The disposable sensor is based on a low-cost label-free three gold electrode commercial sensor for 50-μL volume samples. Forty-eight whole blood samples, randomly collected from hospitalized patients in Hospital Clínic, were used to validate the device capability for anemia detection. Whole blood samples were distributed in two groups: 10 samples for system calibration, and 38 samples for system validation. To calibrate the device, a complete EIS experiment has been performed to get a full impedance spectrum analysis, defining an accurate frequency working range for hematocrit detection. Afterward, we developed a protocol for instant impedance detection to determine the system detection accuracy, sensitivity, and coefficient of variation. As a result, impedance variations between different samples have been detected with less than 2% accuracy error for both impedance magnitude and phase. A hematocrit detection algorithm, relying on impedance analysis, has been developed based on the previous studies. The response, effectiveness, and robustness of the portable PoC device to detect anemia have been proved with an accuracy error of 1.75% and a coefficient of variation of less than 5%.

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

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.

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

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.

Efficient Power Conditioning Circuit for Self-Powered Microsystems (SPMS) based on a Low-Voltage Low-Power 0.13μm Technology

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

Energy Harvesting (Multi Harvesting Power Chip)

There is a growing interest in renewable energy and their applications for both, high and low power systems. Specifically, Energy Harvesting consists in the use of free available energy from the environment, vibrations, heat, light, radio waves or human activities, to power small electronic systems with Low-Voltages and Low-Power consumption. The challenge is to avoid the use of any bulky battery with finite amount of energy and just work directly with the harvested energy and a rechargeable storage element. At that point, Energy Harvesting generators are a promising alternative to generate energy from environment sources and power some applications. Moreover, the use of these generators, with infinite amount of energy, allows the development of autonomous Self-Powered applications. This chapter discusses the development of a real power system based on the recollected energy from several ambient sources. A system able to collect and manage energy from four different power sources, solar light, vibrations, thermal and inductive waves is introduced. Furthermore, the conception is validated with a full-custom Integrated Circuit (IC). Later on, a comprehensive description of all circuits involved in the Multi harvesting system is done; emphasizing the design for Low-Voltage and Low-Power applications.

Low-voltage low-power reference circuits for an autonomous robot : I-SWARM

In this paper it is presented the design of the power supply system for an autonomous robot of few mm3 called I-SWARM (Intelligent Small World Autonomous Robots for Micro-manipulation) which is based on the design of a low-dropout regulator (LDO), and a bandgap reference circuit (BG), that has been designed for the LDO. The paper presents the design, stability issues and full Montecarlo studies about the performances of the BG circuit and the LDO regulator, for different temperature and supply conditions. The regulator has been developed to supply the required voltage for the electronics involved in the robot to be tested in a near future. The regulator is based on a low-dropout linear regulator (LDO). The architecture of the BG is based on a peaking current mirror circuit with MOSFET transistors, working in the sub-threshold region. This architecture is very interesting because it presents a good trade-off between performances, area and power dissipation. These circuits have been designed in a 0.13 &mgr;m technology from ST Microelectronics through the CMP-TIMA service.