J. Georgiou - Academia.edu (original) (raw)

Papers by J. Georgiou

Research paper thumbnail of IEEE Transactions on Biomedical Circuits and Systems information for authors

IEEE Transactions on Biomedical Circuits and Systems, 2012

Research paper thumbnail of NiTi memristive behavior

Microelectronic Engineering

Abstract In this paper, the experimental study and confirmation of the memristive behavior demons... more Abstract In this paper, the experimental study and confirmation of the memristive behavior demonstrated by nanowires made of a smart alloy, namely NiTi, are presented. Further contribution to the characterization of the proposed novel NiTi memristor, included measurements in the ac domain, confirming the memristive nature of these NiTi wires/devices. These measurements included the device's response to triangular current excitation, as well as to pulse driving. In all cases, a study of the noise registered has taken place. According to the theory, since NiTi's memristive behavior is depended on its temperature, it is classified as an extended memristor.

Research paper thumbnail of Gait-based person and gender recognition using micro-doppler signatures

2011 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2011

Abstract The ability to identify an individual quickly and accurately is a critical parameter in ... more Abstract The ability to identify an individual quickly and accurately is a critical parameter in surveillance. Conventional contactless systems are often complex and expensive to implement since video-based processing requires high computational resources. In this paper we present a micro-Doppler (mD) system and a computationally efficient classifier for the purpose of identifying individuals and gender. Walking subjects are successfully classified based on their mD time-frequency signatures. Recognition accuracies as high ...

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

Research paper thumbnail of An FPGA-based approach for parameter estimation in spiking neural networks

2012 IEEE International Symposium on Circuits and Systems, 2012

Abstract We present an FPGA-based approach for estimating the delayed synaptic weights of spiking... more Abstract We present an FPGA-based approach for estimating the delayed synaptic weights of spiking neural networks. Our approach makes explicit use of the fact that reverse engineering of a spiking neural network can be cast as a linear programming problem, whereby the objective function is based on the network spiking activity. The solution is obtained by employing the widely used simplex algorithm. Numerical results on a Xilinx Spartan 3 FPGA board show that the present approach can be used to reproduce a ...

Research paper thumbnail of A Micropower Tilt-Processing Circuit

IEEE Transactions on Biomedical Circuits and Systems, 2009

This paper describes a novel analogue circuit for extracting the tilt angle from the output of a ... more This paper describes a novel analogue circuit for extracting the tilt angle from the output of a standard MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with devices operated in subthreshold, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The hardware has been implemented in AMS 0.35µm 2P4M CMOS technology.

Research paper thumbnail of An analogue micropower log-domain silicon circuit for the Hodgkin and Huxley nerve axon

ISCAS'99. Proceedings of the 1999 IEEE International Symposium on Circuits and Systems VLSI (Cat. No.99CH36349)

In this paper an analogue current-mode skeletal circuit, that is suitable for the realisation of ... more In this paper an analogue current-mode skeletal circuit, that is suitable for the realisation of the Hodgkin and Huxley (HH) nerve axon membrane equations, is presented. The circuit is derived by exploiting the inherent properties of the recently proposed `Bernoulli Cell' to calculate the continuous intermediate state variables of the HH nerve axon equations. HSPICE simulations confirm theoretical expectations, using

Research paper thumbnail of An operating point elimination technique for weak-inversion log-domain filters with multiple operating points

Tutorial Guide. ISCAS 2001. IEEE International Symposium on Circuits and Systems (Cat. No.01TH8573)

ABSTRACT

Research paper thumbnail of An all-subthreshold, 0.75V supply, 2ppm/°C, CMOS Voltage Reference

2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013

ABSTRACT An all-subthreshold CMOS Voltage Reference architecture is presented, which achieves 3rd... more ABSTRACT An all-subthreshold CMOS Voltage Reference architecture is presented, which achieves 3rd order curvature compensation over a wide temperature range. The simulated performance of the proposed architecture with a supply voltage of 0.75V is 2 ppm/°C, over a temperature range of 190 °C (-45 °C to 145 °C). The high order curvature compensation is performed using the non-linearities of an NMOS device, operated in subthreshold, combined with the non-linearities of low-temperature-coefficient poly resistors and high-resistivity poly resistors. The topology achieves a power consumption of 2μW. The design does not require any external components.

Research paper thumbnail of A 3-pin 1V 115µW 176×144 autonomous active pixel image sensor in 0.18µm CMOS

2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011

We present a micropower QCIF image sensor fab- ricated in 0.18µm CMOS technology. Low-power opera... more We present a micropower QCIF image sensor fab- ricated in 0.18µm CMOS technology. Low-power operation is achieved through a system-on-chip design methodology optimiz- ing from device to architecture, yielding a 3-pin autonomous system. Supply voltage and reference are scaled down to 1.0V and400mV,respectively.Comparedtopreviouswork,thisimager consumes 42% less energy per pixel. I. INTRODUCTION

Research paper thumbnail of Bio-inspired micro-fluidic angular-rate sensor for vestibular prostheses

Sensors (Basel, Switzerland), Jan 22, 2014

This paper presents an alternative approach for angular-rate sensing based on the way that the na... more 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 today's state-of-the-art gyroscopes, an ultra-low power consumption of 300 μW is obtained, thus making it suitable for implantation.

Research paper thumbnail of Multimodal integration of micro-Doppler sonar and auditory signals for behavior classification with convolutional networks

International journal of neural systems, 2013

The ability to recognize the behavior of individuals is of great interest in the general field of... more The ability to recognize the behavior of individuals is of great interest in the general field of safety (e.g. building security, crowd control, transport analysis, independent living for the elderly). Here we report a new real-time acoustic system for human action and behavior recognition that integrates passive audio and active micro-Doppler sonar signatures over multiple time scales. The system architecture is based on a six-layer convolutional neural network, trained and evaluated using a dataset of 10 subjects performing seven different behaviors. Probabilistic combination of system output through time for each modality separately yields 94% (passive audio) and 91% (micro-Doppler sonar) correct behavior classification; probabilistic multimodal integration increases classification performance to 98%. This study supports the efficacy of micro-Doppler sonar systems in characterizing human actions, which can then be efficiently classified using ConvNets. It also demonstrates that t...

Research paper thumbnail of A Reduced-Area, Low-Power CMOS Bandgap Reference Circuit

2007 IEEE International Symposium on Circuits and Systems, 2007

This paper presents a low-voltage, reduced-area CMOS bandgap reference (BGR) circuit for low-powe... more This paper presents a low-voltage, reduced-area CMOS bandgap reference (BGR) circuit for low-power applications. Significant area reduction is achieved by utilizing a resistive T-network in combination with layout-efficient opamp compensation. A complete analysis, including the dual-loop stability, reveals several tradeoffs between area, loop-gain, stability and offset sensitivity. Based on this analysis, a high-performance design, in a 0.18mum CMOS process, is

Research paper thumbnail of Holistic Electron. Res. Lab., Univ. of Cyprus, Nicosia, Cyprus

Research paper thumbnail of Designing hybrid photovoltaic – thermoelectric energy systems

Research paper thumbnail of A wireless architecture for distributed sensing/actuation and pre-processing with microsecond synchronization

2011 45th Annual Conference on Information Sciences and Systems, 2011

Research paper thumbnail of Human Action Categorization Using Ultrasound Micro-Doppler Signatures

Lecture Notes in Computer Science, 2011

Research paper thumbnail of A multimodal-corpus data collection system for cognitive acoustic scene analysis

Abstract We report on the design and the collection of a multi-modal data corpus for cognitive ac... more Abstract 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 people's 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 ...

Research paper thumbnail of Acceleration-dependent sampling for ingestible endoscopic imaging capsule

2012 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2012

ABSTRACT

Research paper thumbnail of An optoelectronic/microfluidic inclination sensor for vestibular implants

2009 IEEE Biomedical Circuits and Systems Conference, 2009

We present a MEMS device fabricated in the SensoNor MultiMEMS process to replicate the tilt sensi... more We present a MEMS device fabricated in the SensoNor MultiMEMS process to replicate the tilt sensing function of the human vestibular system. Our device uses opaque fluid movement within a cavity to govern the amount of light that reaches strategically placed photosensing regions. In addition to the device we have included various structures so that we can determine the performance

Research paper thumbnail of IEEE Transactions on Biomedical Circuits and Systems information for authors

IEEE Transactions on Biomedical Circuits and Systems, 2012

Research paper thumbnail of NiTi memristive behavior

Microelectronic Engineering

Abstract In this paper, the experimental study and confirmation of the memristive behavior demons... more Abstract In this paper, the experimental study and confirmation of the memristive behavior demonstrated by nanowires made of a smart alloy, namely NiTi, are presented. Further contribution to the characterization of the proposed novel NiTi memristor, included measurements in the ac domain, confirming the memristive nature of these NiTi wires/devices. These measurements included the device's response to triangular current excitation, as well as to pulse driving. In all cases, a study of the noise registered has taken place. According to the theory, since NiTi's memristive behavior is depended on its temperature, it is classified as an extended memristor.

Research paper thumbnail of Gait-based person and gender recognition using micro-doppler signatures

2011 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2011

Abstract The ability to identify an individual quickly and accurately is a critical parameter in ... more Abstract The ability to identify an individual quickly and accurately is a critical parameter in surveillance. Conventional contactless systems are often complex and expensive to implement since video-based processing requires high computational resources. In this paper we present a micro-Doppler (mD) system and a computationally efficient classifier for the purpose of identifying individuals and gender. Walking subjects are successfully classified based on their mD time-frequency signatures. Recognition accuracies as high ...

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

Research paper thumbnail of An FPGA-based approach for parameter estimation in spiking neural networks

2012 IEEE International Symposium on Circuits and Systems, 2012

Abstract We present an FPGA-based approach for estimating the delayed synaptic weights of spiking... more Abstract We present an FPGA-based approach for estimating the delayed synaptic weights of spiking neural networks. Our approach makes explicit use of the fact that reverse engineering of a spiking neural network can be cast as a linear programming problem, whereby the objective function is based on the network spiking activity. The solution is obtained by employing the widely used simplex algorithm. Numerical results on a Xilinx Spartan 3 FPGA board show that the present approach can be used to reproduce a ...

Research paper thumbnail of A Micropower Tilt-Processing Circuit

IEEE Transactions on Biomedical Circuits and Systems, 2009

This paper describes a novel analogue circuit for extracting the tilt angle from the output of a ... more This paper describes a novel analogue circuit for extracting the tilt angle from the output of a standard MEMS accelerometer. The circuit uses the accelerometer signal together with the gravitational acceleration vector to generate the tilt signal. Using a current-mode representation with devices operated in subthreshold, the appropriate trigonometric function has been realised to compute tilt. Furthermore, implementing a long-time constant filter to extract the mean tilt level provides adaptation to the static tilt level. Specifically, this circuit has been designed as part of an implantable vestibular prosthesis to provide inclination signals for bypassing dysfunctional otolith end-organs. The hardware has been implemented in AMS 0.35µm 2P4M CMOS technology.

Research paper thumbnail of An analogue micropower log-domain silicon circuit for the Hodgkin and Huxley nerve axon

ISCAS'99. Proceedings of the 1999 IEEE International Symposium on Circuits and Systems VLSI (Cat. No.99CH36349)

In this paper an analogue current-mode skeletal circuit, that is suitable for the realisation of ... more In this paper an analogue current-mode skeletal circuit, that is suitable for the realisation of the Hodgkin and Huxley (HH) nerve axon membrane equations, is presented. The circuit is derived by exploiting the inherent properties of the recently proposed `Bernoulli Cell' to calculate the continuous intermediate state variables of the HH nerve axon equations. HSPICE simulations confirm theoretical expectations, using

Research paper thumbnail of An operating point elimination technique for weak-inversion log-domain filters with multiple operating points

Tutorial Guide. ISCAS 2001. IEEE International Symposium on Circuits and Systems (Cat. No.01TH8573)

ABSTRACT

Research paper thumbnail of An all-subthreshold, 0.75V supply, 2ppm/°C, CMOS Voltage Reference

2013 IEEE International Symposium on Circuits and Systems (ISCAS2013), 2013

ABSTRACT An all-subthreshold CMOS Voltage Reference architecture is presented, which achieves 3rd... more ABSTRACT An all-subthreshold CMOS Voltage Reference architecture is presented, which achieves 3rd order curvature compensation over a wide temperature range. The simulated performance of the proposed architecture with a supply voltage of 0.75V is 2 ppm/°C, over a temperature range of 190 °C (-45 °C to 145 °C). The high order curvature compensation is performed using the non-linearities of an NMOS device, operated in subthreshold, combined with the non-linearities of low-temperature-coefficient poly resistors and high-resistivity poly resistors. The topology achieves a power consumption of 2μW. The design does not require any external components.

Research paper thumbnail of A 3-pin 1V 115µW 176×144 autonomous active pixel image sensor in 0.18µm CMOS

2011 IEEE International Symposium of Circuits and Systems (ISCAS), 2011

We present a micropower QCIF image sensor fab- ricated in 0.18µm CMOS technology. Low-power opera... more We present a micropower QCIF image sensor fab- ricated in 0.18µm CMOS technology. Low-power operation is achieved through a system-on-chip design methodology optimiz- ing from device to architecture, yielding a 3-pin autonomous system. Supply voltage and reference are scaled down to 1.0V and400mV,respectively.Comparedtopreviouswork,thisimager consumes 42% less energy per pixel. I. INTRODUCTION

Research paper thumbnail of Bio-inspired micro-fluidic angular-rate sensor for vestibular prostheses

Sensors (Basel, Switzerland), Jan 22, 2014

This paper presents an alternative approach for angular-rate sensing based on the way that the na... more 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 today's state-of-the-art gyroscopes, an ultra-low power consumption of 300 μW is obtained, thus making it suitable for implantation.

Research paper thumbnail of Multimodal integration of micro-Doppler sonar and auditory signals for behavior classification with convolutional networks

International journal of neural systems, 2013

The ability to recognize the behavior of individuals is of great interest in the general field of... more The ability to recognize the behavior of individuals is of great interest in the general field of safety (e.g. building security, crowd control, transport analysis, independent living for the elderly). Here we report a new real-time acoustic system for human action and behavior recognition that integrates passive audio and active micro-Doppler sonar signatures over multiple time scales. The system architecture is based on a six-layer convolutional neural network, trained and evaluated using a dataset of 10 subjects performing seven different behaviors. Probabilistic combination of system output through time for each modality separately yields 94% (passive audio) and 91% (micro-Doppler sonar) correct behavior classification; probabilistic multimodal integration increases classification performance to 98%. This study supports the efficacy of micro-Doppler sonar systems in characterizing human actions, which can then be efficiently classified using ConvNets. It also demonstrates that t...

Research paper thumbnail of A Reduced-Area, Low-Power CMOS Bandgap Reference Circuit

2007 IEEE International Symposium on Circuits and Systems, 2007

This paper presents a low-voltage, reduced-area CMOS bandgap reference (BGR) circuit for low-powe... more This paper presents a low-voltage, reduced-area CMOS bandgap reference (BGR) circuit for low-power applications. Significant area reduction is achieved by utilizing a resistive T-network in combination with layout-efficient opamp compensation. A complete analysis, including the dual-loop stability, reveals several tradeoffs between area, loop-gain, stability and offset sensitivity. Based on this analysis, a high-performance design, in a 0.18mum CMOS process, is

Research paper thumbnail of Holistic Electron. Res. Lab., Univ. of Cyprus, Nicosia, Cyprus

Research paper thumbnail of Designing hybrid photovoltaic – thermoelectric energy systems

Research paper thumbnail of A wireless architecture for distributed sensing/actuation and pre-processing with microsecond synchronization

2011 45th Annual Conference on Information Sciences and Systems, 2011

Research paper thumbnail of Human Action Categorization Using Ultrasound Micro-Doppler Signatures

Lecture Notes in Computer Science, 2011

Research paper thumbnail of A multimodal-corpus data collection system for cognitive acoustic scene analysis

Abstract We report on the design and the collection of a multi-modal data corpus for cognitive ac... more Abstract 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 people's 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 ...

Research paper thumbnail of Acceleration-dependent sampling for ingestible endoscopic imaging capsule

2012 IEEE Biomedical Circuits and Systems Conference (BioCAS), 2012

ABSTRACT

Research paper thumbnail of An optoelectronic/microfluidic inclination sensor for vestibular implants

2009 IEEE Biomedical Circuits and Systems Conference, 2009

We present a MEMS device fabricated in the SensoNor MultiMEMS process to replicate the tilt sensi... more We present a MEMS device fabricated in the SensoNor MultiMEMS process to replicate the tilt sensing function of the human vestibular system. Our device uses opaque fluid movement within a cavity to govern the amount of light that reaches strategically placed photosensing regions. In addition to the device we have included various structures so that we can determine the performance