In this paper, we showcase the innovative concept of implementing Oscillatory Neural Networks (ONNs) for neuromorphic computing with beyond-CMOS devices based on vanadium dioxide to mimic neurons and resistors to emulate synapses. We explore ONN technology potentials from device to analog circuit-level simulations. We report that ONN behaves like an associative memory and can implement energy-based models such as Hopfield Neural Networks on edge devices. Finally, as a proof of concept, a reconfigurable digital ONN is implemented on FPGA for pattern recognition tasks.
Bioimpedance spectroscopy (BIS) is a technique increasingly used for measuring the electrical properties of biological tissues. Choosing an integrated system architecture for bioimpedance spectroscopy is very dependent on the application and ruled by several constraints such as precision, bandwidth and measurement time. This paper presents a hybrid architecture providing fast measurement time while maximizing precision. This new architecture has been defined for a wide exploration of electrical properties of biological tissues. It combines the frequency sweep and multitone measurement techniques. Using the multitone measurement over the α dispersion and a frequency sweep over the β dispersion, enable the system architect to overcome the design challenges faced when using each technique separately. Its critical blocks are optimized for a bandwidth up to 10 MHz, thus covering the α and β frequency ranges, an example of the design optimization is detailed for the current driver.
This paper presents a wideband fully differential current driver architecture suitable for bioimpedance measurements. It uses an improved regulated cascode to enhance output impedance, enabling accurate measurements of transfer impedances at low and high frequencies. The current driver architecture maximizes the output voltage swing. An independent reference voltage is used in order to compensate the process variations of the output common mode voltage. The circuit was designed in 0.18µm CMOS AMS process, operating from 1.8V supply voltage. The silicon area is 0.26 mm 2. The current driver has a 67 MHz bandwidth and can provide a maximum output current of 600 µA peak to peak with a Total Harmonic Distortion (THD) below 0.3% at low frequencies increasing to 0.6% at 8 MHz. Due to the use of regulated cascodes in the output stage, the circuit achieves a 79MΩ output impedance at low frequencies decreasing to 324KΩ at 1MHz, with an output voltage swing of 0.95 V.
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