Transcending Conventional Biometry Frontiers: Diffusive Dynamics PPG Biometry

This paper presents the first photoplethysmographic (PPG) signal dynamic-based biometric authentication system with a Siamese convolutional neural network (CNN). Our method extracts the PPG signal’s biometric characteristics from its diffusive dynamics, characterized by geometric patterns in the (p,q)-planes specific to the 0–1 test. PPG signal diffusive dynamics are strongly dependent on the vascular bed’s biostructure, unique to each individual. The dynamic characteristics of the PPG signal are more stable over time than its morphological features, particularly in the presence of psychosomatic conditions. Besides its robustness, our biometric method is anti-spoofing, given the complex nature of the blood network. Our proposal trains using a national research study database with 40 real-world PPG signals measured with commercial equipment. Biometric system results for input data, raw and preprocessed, are studied and compared with eight primary biometric methods related to PPG, achieving the best equal error rate (ERR) and processing times with a single attempt, among all of them.

Exponentiation conversion circuit capable of changing the power exponent to any value

We proposed an exponentiation conversion circuit which can change its power exponent to any value to compensate the nonlinearity of electronic devices. The proposed circuit is a small scale circuit utilizing the exponential characteristic in the subthreshold operation of MOSFET. In the proposed circuit, the new exponential conversion circuit converts signal multiplied logarithmically transformed input signal by the power exponent value, thereby obtaining the exponential power raised power function characteristic. The proposed circuit is suitable to integrate on a microcomputer chip used for IoT. The performance of the circuit was evaluated by a prototype IC made by 0.6 μm CMOS process. In measured results, the exponential conversion characteristics as set were obtained, the exponent value was set to 0.50, 1.00 and 2.00. By using the cascode exponential conversion circuit, the signal dynamic range was expanded by 5.2 dB when the exponent value was set to 2.00.

Optimized Design of OTA-Based Gyrator Realizing Fractional-Order Inductance Simulator: A Comprehensive Analysis

A detailed analysis of an operational transconductance amplifier based gyrator implementing a fractional-order inductance simulator is presented. The influence of active element non-ideal properties on the gyrator operation is investigated and demonstrated by admittance characteristics and formulas for important values and cut-off frequencies in these characteristics. Recommendations to optimize the performance of the gyrator in terms of operation bandwidth, the range of obtainable admittance magnitude, and signal dynamic range are proposed. The theoretical observations are verified by PSpice simulations of the gyrator with LT1228 integrated circuit.