Ultra Low Power Bandgap Strom- und Spannungsquellen in CMOS-Technologie für integrierte drahtlose Systeme

In modernen drahtlosen Systemen sind niedriger Stromverbrauch und das Betreiben bei niedriger Spannung (Low Voltage Operation) von entscheidender Bedeutung. Dabei ist für viele elektronische Anwendungen eine genaue Spannungs- bzw. Stromreferenz notwendig. Aus diesem Grund werden an eine Referenzquelle hohe Anforderungen bezüglich ihrer Temperatur- und Langzeitstabilität gestellt, was gleichzeitig schwierig mit den &quot;Low-Power&quot; Anforderungen zu vereinbaren ist. <P> Besonders für die auf passiven Transpondern basierenden RFID-Systeme, bei denen die Energieversorgung der Schaltung aus dem Hochfrequenzträgersignal gewonnen wird, stellt die Erzeugung einer genauen Spannungsreferenz ein Problem dar. Vor allem die Spannungsstabilität und die Unabhängigkeit von Temperatur- und Prozessschwankungen bereiten große Schwierigkeiten. <P> In diesem Artikel wird das Design einer CMOS Bandgap Strom- und Spannungsreferenz, realisiert in einer 0,25 μm CMOS-Prozess-Technologie, mit 2,5 V Versorgungsspannung vorgestellt. Die entwickelte Schaltung hat eine Stromaufnahme von 50 μA bei einer Genauigkeit von 1% im Temperaturbereich von &ndash;40&deg;C bis 125&deg;C. Ein Testchip wurde in die Fertigung eingespeist. Ausgehend von einem Überblick über bekannte Realisierungen von Bandgap-Schaltungen wird die Besonderheit der neu entwickelten Low-Power Schaltung vergleichend gegenübergestellt

High resolution delay locked loop for time synchronization with multi path mitigation

Accurate localization Systems, based on the measurement of the time of flight of a signal between radio devices, also known as Real Time Location Systems (RTLS) are becoming increasingly important especially in indoor applications. Due to severe multi path conditions, the largest problem for those RTLS systems is to detect the time of arrival of signals traveling over the direct line of sight path. We present issues of a new High Resolution Delay Locked Loop (HRDLL) architecture- that allows an efficient hardware implementation of a high resolution method for multi path mitigation, and demonstrate first results

Towards a monolithic integrated stimulator with integrated image sensor for a wide-angle retina implant

Objective: To present a monolithic integrated current controlled stimulator (CCS) with a build-in image sensor for a novel independent epiretinal prosthesis with a wide angle field of view (FOV). Materials & Methods: Existing subretinal implants are limited in size by different medical boundary conditions, like the increasing risk of retina detachment. To create a novel wide angle FOV retinal prosthesis, a large carrier foil with several independent microchips is placed as an epiretinal implant and is capable of stimulating a large area of the retina through its backside electrodes. The high flexibility of the foil makes the implant bendable, which allows the implant to fit its shape to the spherical retina. Also the implant is designed to be foldable, which makes it implantable through the cornea. For this kind of implant a new application specific integrated circuit (ASIC) had to be designed for the stimulation of the retina. The ASIC contains an image sensor and controls the electrodes underneath it. Therefore the ASIC detects the local brightness on each pixel to generate the stimulation waveforms for the electrodes which corresponds to the illuminated area. The CCS signal is a biphasic constant current pulse and can be parametrized for different stimulation intensities. Discussion: The ASIC works independent since image sensor and signal processing chain are fully integrated. Thus the system is completely capsuled and only needs an external wireless power supply. The use of multiple ASICs on one single carrier foil allows stimulating a large retinal area. Because the camera is included in the eye, the projected image correlates to eye movements. Acknowledgment: This research is sponsored by the German Research Foundation (DFG) under contract No. GR3328/10-1

An ultra-low noise capacitance to voltage converter for sensor applications in 0.35 µm CMOS

In this paper we present a readout circuit for capacitive micro-electro-mechanical system (MEMS) sensors such as accelerometers, gyroscopes or pressure sensors. A flexible interface allows connection of a wide range of types of sensing elements. The ASIC (application-specific integrated circuit) was designed with a focus on ultra-low noise operation and high analog measurement performance. Theoretical considerations on system noise are presented which lead to design requirements affecting the reachable overall measurement performance. Special emphasis is put on the design of the fully differential operational amplifiers, as these have the dominant influence on the achievable overall performance. The measured input referred noise is below 50 zF/Hz within a bandwidth of 10 Hz to 10 kHz. Four adjustable gain settings allow the adaption to measurement ranges from ±750 fF to ±3 pF. This ensures compatibility with a wide range of sensor applications. The full input signal bandwidth ranges from 0 Hz to more than 50 kHz. A high-precision accelerometer system was built from the described ASIC and a high-sensitivity, low-noise sensor MEMS. The design of the MEMS is outlined and the overall system performance, which yields a combined noise floor of 200 ng/Hz, is demonstrated. Finally, we show an application using the ASIC together with a CMOS integrated capacitive pressure sensor, which yields a measurement signal-to-noise ratio (SNR) of more than 100 dB

Employing beam-forming for estimating the direction of arrival in a multi-path propagation environment

Due to recent researches on traffic accidents with vulnerable road users (VRUs), several measures revealed a great opportunity of reduction. However, all measures applied so far failed to reduce the number of traffic accidents if there is no line-of-sight. Therefore, a transponder signal is utilized to make the VRU visible. The motor vehicle carries a mobile receiver for VRU detection and location. The receiver employs digital beam-forming for estimating the direction of arrival (DOA) with an antenna array for RF ISM band. A sequence of DOA estimations is used for location and motion estimation purposes

Vorrichtung und Verfahren zur Gleichrichtung einer Eingangswechselspannung

DE 102008049648 A1 UPAB: 20100428 NOVELTY - The arrangement (400) has rectifier switches (402, 404) for supplying rectified voltages (Vb, Vdd) based on input alternating voltage. A transistor i.e. FET, acting as a diode has threshold voltage. A compensation circuit (406) arranged between an output of one of the switches and a control port of the transistor supplies compensation voltage to the control port such that current flow is provided between sink and source connections of the transistor with a voltage between the connections. The voltage is smaller than the threshold voltage. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) a transponder comprising an antenna (2) a method for rectifying input alternating voltage. USE - Rectifier arrangement for use in a transponder (claimed). ADVANTAGE - The compensation circuit supplies the compensation voltage to the control port such that the current flow is provided between sink and source connections of the transistor with the voltage between the connections, thus enabling threshold compensation with stress intensification