Charalambos M. Andreou

A Novel Wide-Temperature-Range, 3.9 ppm/

This paper presents an innovative CMOS Bandgap Reference Generator topology that leads to an improved curvature compensation method over a very wide temperature range. The proposed design was implemented in a standard 0.35 μm CMOS process. The compensation is performed by using only poly-silicon resistors. This is achieved by using a second Op-amp that generates a CTAT current, which is subsequently used to enhance the curvature compensation method. The performance of the circuit was verified experimentally. Measured results have shown temperature coefficients as low as 3.9 ppm/^°C over a temperature range of 165^°C ( -15^°C to 150^°C ) and temperature coefficients as low as 13.7 ppm/^°C over an extended temperature range of 200^°C (-50^°C to 150^°C ). In addition the circuit demonstrated very good line regulation performance for a broad range of supply voltages. The measured line regulation at room temperature is 0.039% V.

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The spectrotemporal representation of an ultrasonar wave reflected by an object contains frequency shifts corresponding to the velocity of the objects moving parts, also known as the micro-Doppler signature. The present study describes how the micro-Doppler signature of human subjects, collected in two experiments, can be used to categorize the action performed by the subject. The proposed method segments the spectrogram into temporal events, learns prototypes and categorizes the events using a Nearest Neighbour approach. Results show an average accuracy above 95%, with some categories reaching 100%, and a strong robustness to variations in the model parameters. The low computational cost of the system, together with its high accuracy, even for short length inputs, make it appropriate for a real-time implementation with applications to intelligent surveillance, monitoring and related disciplines.

C CMOS Bandgap Reference Circuit

This paper presents an alternative approach for angular-rate sensing based on the way that the natural vestibular semicircular canals operate, whereby the inertial mass of a fluid is used to deform a sensing structure upon rotation. The presented gyro has been fabricated in a commercially available MEMS process, which allows for microfluidic channels to be implemented in etched glass layers, which sandwich a bulk-micromachined silicon substrate, containing the sensing structures. Measured results obtained from a proof-of-concept device indicate an angular rate sensitivity of less than 1 °/s, which is similar to that of the natural vestibular system. By avoiding the use of a continually-excited vibrating mass, as is practiced in todays state-of-the-art gyroscopes, an ultra-low power consumption of 300 μW is obtained, thus making it suitable for implantation.

Human action categorization using ultrasound micro-doppler signatures

This paper proposes a new CMOS Bandgap Reference Generator topology that allows a straightforward implementation of an exact curvature compensation method by using only poly-silicon resistors. This is achieved by using a second Opamp that generates a CTAT current, which is subsequently used to enhance the curvature compensation method. A superior theoretical performance than previously proposed architectures is achieved with respect to temperature sensitivity of the reference voltage. In nominal simulations, that was less than 0.lppm over a temperature range of −40 to 125 for a CMOS 0.35μm technology. In practice, the proposed BGR is sensitive to device mismatch and thus resistor trimming is necessary if high performance is required.

Bio-inspired micro-fluidic angular-rate sensor for vestibular prostheses.

A low-voltage, low-power, low-area, wide-temperature-range CMOS voltage reference is presented. The proposed reference circuit achieves a measured temperature drift of 15ppm/i¾źC for an extremely wide temperature range of 190i¾źC -60 to 130i¾źC while consuming only 4µW at 0.75V. It performs a high-order curvature correction of the reference voltage while consisting of only CMOS transistors operating in subthreshold and polysilicon resistors, without utilizing any diodes or external components such as compensating capacitors. A trade-off of this circuit topology, in its current form, is the high line sensitivity. The design was fabricated using TowerJazz semiconductors 0.18-µm standard CMOS technology and occupies an area of 0.039mm2. The proposed reference circuit is suitable for high-precision, low-energy-budget applications, such as mobile systems, wearable electronics, and energy harvesting systems. Copyright

A novel CMOS Bandgap reference circuit with improved high-order temperature compensation

We report on the design and the collection of a multi-modal data corpus for cognitive acoustic scene analysis. Sounds are generated by stationary and moving sources (people), that is by omni-directional speakers mounted on peoples heads. One or two subjects walk along predetermined systematic and random paths, in synchrony and out of sync. Sound is captured in multiple microphone systems, including a four MEMS microphone directional array, two electret microphones situated in the ears of a stuffed gerbil head, and a Head Acoustics, head-shoulder unit with ICP microphones. Three micro-Doppler units operating at different frequencies were employed to capture gait and the articulatory signatures as well as location of the people in the scene. Three ground vibration sensors were recording the footsteps of the walking people. A 3D MESA camera as well as a web-cam provided 2D and 3D visual data for system calibration and ground truth. Data were collected in three environments ranging from a well controlled environment (anechoic chamber), an indoor environment (large classroom) and the natural environment of an outside courtyard. A software tool has been developed for the browsing and visualization of the data.

A 0.75-V, 4-µW, 15-ppm/źC, 190źC temperature range, voltage reference

In this paper we present a micro-Doppler (mD) system and a computationally efficient classifier for the purpose of distinguishing different means of transport for human beings (pedestrians, inline skaters and cyclists) based on their mD time-frequency signatures. Accuracies as high as 97% are obtained while keeping the overall computational cost low.

A multimodal-corpus data collection system for cognitive acoustic scene analysis

This paper presents a novel hybrid CMOS/MEMS tilt sensor with a 5deg resolution over a 330deg range. The device uses a MEMS-based semicircular mass suspended from a rigid body, projecting a shadow onto the CMOS-based optical sensor surface. A one-dimensional photodiode array arranged as a uniformly segmented ring is then used to determine the tilt angle by detecting the position of the semicircular mass. The complete sensor occupies an area of under 2.5 m times 2.5 mm.

Computationally efficient classification of human transport mode using micro-doppler signatures

A low-power, wide temperature range, radiation tolerant CMOS voltage reference is presented. The proposed reference circuit exhibits a voltage deviation of 0.8mV for 3-MeV protons total ionization dose of 2Mrad and a voltage deviation of 3.8mV for 10-keV X-rays total ionization dose of 4Mrad while being biased at the nominal supply voltage of 0.75V during X-ray irradiation. In addition, the circuit consumes only 4μW and exhibits a measured Temperature Drift of 15ppm/°C for a temperature range of 190°C (-60°C to 130°C) at the supply voltage of 0.75V. It utilizes only CMOS transistors, operating in the subthreshold regime, and poly-silicon resistors without using any diodes or external components such as compensating capacitors. The circuit is radiation hardened by design (RHBD), it was fabricated using TowerJazz Semiconductors 0.18μm standard CMOS technology and occupies a silicon area of 0.039mm2. The proposed voltage reference is suitable for high-precision and low-power space applications.

An ultra-low-power micro-optoelectromechanical tilt sensor

We present a micropower QCIF image sensor fabricated in 0.18µm CMOS technology. Low-power operation is achieved through a system-on-chip design methodology optimizing from device to architecture, yielding a 3-pin autonomous system. Supply voltage and reference are scaled down to 1.0V and 400mV, respectively. Compared to previous work, this imager consumes 42% less energy per pixel.