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This paper discusses the application of coupled reactance-less memristor-based oscillators (MBO) with binary output signals in oscillatory networks. A class of binary-coupled memristor oscillators provides simple integration with standard CMOS logic elements. Combining MBOs with binary logic elements ensures the operation of complex information processing algorithms. The analysis of the simplest networks based on MBOs is performed. The typical reactance-less MBO with current and potential inputs is considered. The output responses for input control signals are analyzed. It is shown that the current input signal impacts primarily the rate of memristor resistance variation, while the potential input signal changes the thresholds. The exploit of the potential input for the synchronization of coupled MBOs and current control input in order to provide the necessary encoding of information is suggested. The example of the application of coupled MBOs in oscillatory networks is given, and results of simulation are presented.

In this work we present an in-memory computing platform based on coupled VO2 oscillators fabricated in a crossbar configuration on silicon. Compared to existing platforms, the crossbar configuration promises significant improvements in terms of area density and oscillation frequency. Further, the crossbar devices exhibit low variability and extended reliability, hence, enabling experiments on 4-coupled oscillator. We demonstrate the neuromorphic computing capabilities using the phase relation of the oscillators. As an application, we propose to replace digital filtering operation in a convolutional neural network with oscillating circuits. The concept is tested with a VGG13 architecture on the MNIST dataset, achieving performances of 95% in the recognition task.

Neuromorphic computing using neural network hardware has attracted significant interest as it promises improved performance at low power for data-intensive error-resilient graphical signal processing. Oscillatory neural networks (ONNs) use either frequency or phase as state variables to implement frequency-shift keying (FSK)- and phase-shift keying (PSK)-based neural networks, respectively. To make these ONNs power and area efficient, back-end-of-the-line compatible, and capable of processing multilevel information, we explore an emerging class of oscillators that show fine-grain frequency-tuning and phase-coupling. We examine TaOx- and TiOx-based oscillators (resistive random access memory-type) as elements of a neuromorphic compute block and experimentally demonstrate: 1) frequency control over four decades using a ballast MOSFET; 2) variable phase coupling between oscillators; and 3) variable phase programming between oscillators coupled with a MOSFET. Such fine-grain control over both frequency and relative phase serve as the desirable characteristics of oscillators required for multilevel information processing in star-type directly coupled FSK- and PSK-based neuromorphic systems that find applications in gray-scale image processing and other graphical compute paradigms. These attributes combined with the small size (2) and simplicity, make these devices attractive candidates for realizing large-scale neuromorphic systems at reasonable size and power.

This paper presents the analysis and experimental results on the noise performances of a capacitive-sensor interface. The interface is able to measure low capacitance values in the order of picofarads and is implemented with a simple relaxation oscillator, a fast counter, and a microcontroller. The goal is to find the criteria to implement a low-noise system, so that, even with a short measuring time, low noise can be obtained. Experimental results are performed in order to prove the validity of the theoretical analysis. The achieved resolution, with a measuring time of 20 ms, was better than 14.2 /spl times/ 10/sup -7/ for the measurement of a capacitance value of 2.2 pF.

A novel signal conditioning circuit suitable for push-pull-type resistive transducers is proposed. The circuit developed is capable of providing a linear output over a wide range of values of the measurand. Even when the transducer has an inverse relationship with the measurand, the circuit provides a linear output. The push-pull-type resistive transducer becomes an integral part of a relaxation oscillator, the duty cycle ratio of the output of which becomes proportional to the measurand. Since the output depends only on the relative sensitivity of the transducer and a pair of dc excitation voltages, it is possible to obtain very low errors. The various sources of error in the circuit are analysed and quantitative expressions to estimate such errors are derived. The circuit was set up in the laboratory and the results obtained from the prototype are presented. The prototype possessed an error of �0.02% of the reading. It is seen that this circuit is not only simple but also produces errors which are much less than those from circuits currently mentioned in the literature. ? 2005 IOP Publishing Ltd.

The design of a 100 kHz frequency reference based on the electron mobility in a MOS transistor is presented. The proposed low-voltage low-power circuit requires no off-chip components, making it suitable for application in wireless sensor networks (WSN). After a single-point calibration, the spread of its output frequency is less than 1.1% (3sigma) over the temperature range from -22degC to 85degC . Fabricated in a baseline 65 nm CMOS technology, the frequency reference circuit occupies 0.11 mm2 and draws 34 muA from a 1.2 V supply at room temperature.

The goal of this paper is to show that a distributed consensus mechanism can be implemented in a wireless sensor network exploiting the synchronization capabilities of relaxation oscillators, properly initialized with the measurements taken by their associated sensors. Relaxation oscillators are dynamic systems characterized by testability and high flexibility to produce waveforms with different characteristics. In particular, initializing each system with a function of the measurement, the state of the system may end up into two possible stable trajectories: a constant waveform, corresponding to a stable equilibrium point, or a periodic waveform, corresponding to a limit cycle. In the first case, the node does not transmit any signal. Conversely, in the second case, the node transmits a periodic signal like, e.g., a train of pulses. The approach proposed in this work has two purposes: a) design the oscillators' parameters so that they do not transmit when the measurement falls below a given threshold or they transmit a periodic pulse train, with a period inversely proportional to the measurement, when the measurement exceeds the threshold; b) make nearby oscillators to interact with each other in order to reach a consensus over globally optimal test statistics. Finally, the proposed scheme is applied to distributed multiple hypothesis testing for the recognition of the field monitored by a planar sensor network.

A linear variable differential capacitive transducer for the measurement of planar angles (from 0� to 360�) is presented in this paper. The sensor part of the transducer is made of parallel plates of standard and easy-to-fabricate shapes, and the signal-conditioning electronics are realized, employing a couple of simple relaxation oscillators. The output of the transducer is only dictated by a pair of dc reference voltages, and hence, high accuracy and linearity over the entire range (from 0� to 360� are easily obtained by the use of precision dc reference voltages. Detailed analysis indicates that the sensitivity of the transducer is minimal for variations in different parameters. Experimental results obtained on a prototype transducer that has been built and tested establish the efficacy of the proposed transducer. The worst-case error of the prototype transducer is found to be less than 0.1%. � 2008 IEEE.

We study the transient synchronization dynamics of locally coupled phase oscillators moving on a one-dimensional lattice. Analysis of spatial phase correlation shows that mobility speeds up relaxation of spatial modes and leads to faster synchronization. We show that when mobility becomes sufficiently high, it does not allow spatial modes to form and the population of oscillators behaves like a mean-field system. Estimating the relaxation timescale of the longest spatial mode and comparing it with systems with long-range coupling, we reveal how mobility effectively extends the interaction range. © 2013 American Physical Society.