Design of Operational Transconductance Amplifiers for voltage to current conversion in gas sensing applications

This paper presents a study of Operational Transconductance Amplifiers (OTAs) for voltage to current conversion circuits. The paper includes a comparative analysis of three OTA architectures implemented in 0.35\u3bcm CMOS AMS Technology under \ub1 1.65V power supply voltage. The impact of the OTA topology has been investigated by simulation. The designed OTAs managed to deliver large current values of 10mA and 1mA to the load with a worst-case error of 0.02% under worst-case power supply and temperature conditions and a worst percentage error of 0.12% under process variation for both Miller Compensated and Capacitor Multiplier Compensated OTA. \ua9 2016 AEIT

Design and Non-linear Modelling of CMOS Multipliers for Analog VLSI Implementation of Neural Algorithms

: The analog VLSI implementation looks an attractive way for implementing Artificial Neural Networks; in fact, it gives small area, low power consumption and compact design of neural computational primitive circuits. On the other hand, major drawbacks result to be the low computational accuracy and the non-linear behaviour of analog circuits. In this paper, we present the design and the detailed behavioural models of CMOS multipliers for the analog VLSI implementation of neural algorithms. The circuits implement the feedforward operations of the Multi Layer Perceptron architecture and of the Back Propagation (on-chip learning) algorithm; they operate in the subthreshold regime to obtain a low power consumption and high dynamic range of weights. The circuit behavioural models take into account: i) non-linearity effects; ii) environmental effects (variations of temperature and of signal reference voltage). The models that we present in this paper, are used in the behavioural validation o..

Embedded electronic systems for tactile data processing

The development of embedded electronic systems for tactile data processing is increasingly demanded for many application domains e.g. robotics, prosthetics, industrials automation etc. In this paper we present the requirements for the embedded electronic system implementation of real time tactile data processing based on Tensorial Kernel approach. The paper provides the performance analysis of the FPGA implementation methods of the singular value decomposition as a result on the way to achieve the desired system. \ua9 Springer International Publishing AG 2017

Noisy reading correction in low power MPPT using kalman filter

Kalman filter is designed to predict the correct values for noisy measurements, using a probabilistic model. However, the chosen system model has a huge impact on the outcome of this algorithm, which makes it very important for the model to be as representative of the system as possible. A new approach to handle the noisy measurements in low power Maximum Power Point Tracking (MPPT) algorithms is presented in this paper. The proposed filtering proved beneficial in terms of algorithm stability

Differential R-to-I conversion circuit for gas sensing in biomedical applications

In biomedical engineering specifically gas sensing applications, the concentration of the exhaled gas is converted to a variation in resistance, thus an electronic integrated interface circuit is required to analyze the exhaled gases, which are indications for many diseases. In this paper, a differential resistance to current conversion circuit for Electronic nose (E-nose) breath analyzer is presented. Over an input resistance range of more than 5-decades (500\u3c9 to 100M\u3c9), a precision, less than 1%, required by novel gas sensing system in portable applications, is preserved. As a result, the proposed circuit obtains high accuracy under simulation. The outputs of the proposed Resistance to Current (R-to-I) conversion circuit achieve a percentage error below 0.25% under environment corners. The reliability of the proposed circuit is also investigated under the effect of process variations. In order to assess the correctness of the proposed architecture, the circuit was compared to similar solutions presented in literature. The proposed architecture attains a worst-case percentage error of 0.05%. \ua9 2016 IEEE

Design of an analog CMOS self-learning MLP chip

In this paper we present the analog CMOS design of a Multi-Layer-Perceptron network with on-chip by-pattern Back-Propagation learning. The learning algorithm is based on a local learning rate adaptation technique which makes the on-chip implementation more efficient in terms of convergence speed. Circuit simulation results validate the network behavior

Inexact Arithmetic Circuits for Energy Efficient IoT Sensors Data Processing

Developing portable autonomous systems is highly requested for numerous application domains such as Internet of Things (IoT), wearable devices, and biomedical applications. Portable systems usually contain autonomous and networked sensors; each sensor hosts multiple input channels (e.g. tactile) closely coupled to embedded computing unit and power supply. The embedded computing unit should locally extract meaningful information by employing sophisticated methods. This imposes challenges on real time operation and adds a burden regarding power consumption. Approximate or inexact computing represents a promising solution for energy efficient data processing; it tunes the accuracy of computation on the specific application requirements in order to reduce power consumption. In this paper, inexact arithmetic circuits have been employed to improve the energy efficiency for sensors digital data processing. The proposed inexact circuits achieve up to 80% power saving when compared to the exact one, and similar solutions presented in literature with a maximum loss of 1.39 dB in output SNR when applied to FIR filters. \ua9 2018 IEEE

Wide range resistance to current conversion circuit for resistive gas sensors applications

Due to their physical principle of operation, resistive gas sensors require very wide range interface circuit. Thus, to design the integrated read out solution, the accuracy in the converted data should be preserved. In this paper, a wide range resistance to current conversion circuit for gas sensing applications is designed. High linear current mirror in push pull configuration is implemented as well. Simulation results show that the circuit achieves a percentage error in the converted current between 0.12% and 0.25% over 7 decades for the sensor's resistance ranging from 100\u3a9 to 1G\u3a9. The current mirror achieves an absolute percentage gain factor error of 0.2% and 0.46% for PMOS and NMOS current mirrors respectively

Multi-Channel Electrotactile Stimulation System for Touch Substitution: A Case Study

Reconstructing the sense of touch in prosthetics is a long-standing research challenge. To this aim, the prosthesis can be supplied with sensory arrays to measure the tactile interaction with the environment. In addition, a reliable feedback system is required to code and transmit the measured somatosensory information to the residual limb. This paper presents a multichannel electrotactile stimulation interface. Two coding schemes (mixed and uniform coding) were tested to assess the ability of the subject to localize the stimulation (identify the active pad). The outcome measures were position recognition and frequency discrimination. Our preliminary results show high accuracies in discriminating different frequency levels, i.e., 80% for low-level frequencies and 87% for high-level frequencies. In addition, the mixed coding has substantially improved the spatial localization. These are important insights regarding the development of multichannel sensing and stimulation systems for feedback in prosthetics. \ua9 2018 IEEE

Approximate multipliers based on inexact adders for energy efficient data processing

Approximate computing circuits are considered as a promising solution to reduce the power consumption in embedded data processing. This paper proposes an FPGA implementation for an approximate multiplier based on inexact adder circuits. The performance of the proposed multiplier is evaluated by comparing the power consumption, the accuracy of computation, and the time delay with those of an approximate multiplier based on exact adder presented in literature. Results reports a power saving up to 17.39% with an improvement in time delay by 13.49%, at cost of less than 5% of accuracy loss. \ua9 2017 IEEE