Programmable Analog Filters Research Articles

Analog Memristor-Based Dynamic Programmable Analog Filter

The memristor study now generally exhibit threshold voltage characteristics. The memristance changes when the voltage across the memristor is greater than the threshold voltage. Otherwise, the memristance is almost constant. Based on this feature, we design a general-purpose memristor programmable circuit that is simple to operate. In the field of communication and signal processing, programmable analog filters are required, and memristors with multi-valued characteristic are suitable as programmable impedance elements for such circuits. Through simulation and physics experiments, we demonstrate a memristor-based programmable low-pass filter using the designed programmable circuit to realize the dynamic adjustment of circuit parameters.

Memristive and Memory Impedance Behavior in a Photo-Annealed ZnO–rGO Thin-Film Device

An oxygen-rich ZnO-reduced graphene oxide (rGO) thin film was synthesized using a photo-annealing technique from zinc precursor (ZnO)–graphene oxide (GO) sol–gel solution. X-ray diffraction (XRD) results show a clear characteristic peak corresponding to rGO. The scanning electron microscope (SEM) image of the prepared thin film shows an evenly distributed wrinkled surface structure. Transition Metal Oxide (TMO)-based memristive devices are nominees for beyond CMOS Non-Volatile Memory (NVRAM) devices. The two-terminal Metal–TMO (Insulator)–Metal (MIM) memristive device is fabricated using a synthesized ZnO–rGO as an active layer on fluorine-doped tin oxide (FTO)-coated glass substrate. Aluminum (Al) is deposited as a top metal contact on the ZnO–rGO active layer to complete the device. Photo annealing was used to reduce the GO to rGO to make the proposed method suitable for fabricating ZnO–rGO thin-film devices on flexible substrates. The electrical characterization of the Al–ZnO–rGO–FTO device confirms the coexistence of memristive and memimpedance characteristics. The coexistence of memory resistance and memory impedance in the same device could be valuable for developing novel programmable analog filters and self-resonating circuits and systems.

Upgrading a Low-Cost System for Measuring Lightning Electric Field Waveforms

Recent upgrades of the low-cost lightning detection and waveform storage system (LDWSS) are presented. The system has been developed for research and operational use in the Amazon region of Brazil and it has been in operation in this region since November 1, 2017. The original version of the LDWSS operated for 10 months at the Lightning Observatory in Gainesville, Florida, where it was calibrated and tested. Two main modifications implemented include the improvement of the effective dynamic range and the capability to detect lightning in different frequency bands. The improvements were achieved by using two pre-amplifiers working in parallel, a new processing (smart saving) algorithm, and programmable analog filters. As a result, a single, low-cost lightning electric field measuring system allows one to record both close and far lightning events with good amplitude resolution and without saturation, and study both wideband and narrow-band (for example, very low frequency) field signatures of lightning, without modifying the hardware.

Flexible frequency selective passive circuits based on memristor and capacitor

Abstract In analog electronic communication and signal processing applications, programmable analog filters are desirable to reduce the hardware requirement. Memristor is two states configurable nonvolatile resistor, which is small size, low power, and fast switching device. To achieve tunable cut-off frequency and bandwidth, flexible memristor-capacitor (MC) circuits are proposed, which can be applied as low pass, high pass, and band pass filters. They can be fabricated on a flexible polyethylene terephthalate (PET) substrate through electrohydrodynamic (EHD) technique. In the proposed filters, two cut-off frequencies are selected through switching two resistive states of the memristor either in high resistance state (HRS) or low resistance state (LRS), whereas the capacitor has a fixed value. The memristor is composed of graphene quantum dots (GQDs)/poly 4-vinlyphenol (PVP) composite to achieve highly stable and linear behavior and the dielectric layer of capacitor is consisted of graphene/PVP composite. The fabricated MC filters are electrically and mechanically characterized, which are matched quite well with theoretical results. From these results, it can be a good basis for tunable analog filters in wearable electronics.

A general memristor model and its applications in programmable analog circuits

This paper focuses on presenting a new memristor model with a general window function. Three adjustable parameters are introduced such that it is more flexible. It is seen that several well-known window functions are the special cases of the general window function. Some issues (e.g., the boundary lock and limited scalability) encountered in previously reported memristor models are thus efficiently resolved. Furthermore, fine-resolution programmable resistance is achieved by controlling the parameters of the general memristor model. The programmable analog filter and gain amplifier are finally implemented to illustrate the applications of the developed memristor model.

Generalized boundary condition memristor model

SUMMARYA number of resistive switching memories exhibit activation‐based dynamical behavior, which makes them suitable for neuromorphic and programmable analog filtering applications. Because the Boundary Condition Memristor (BCM) model accounts for tunable activation thresholds only at the on and off boundary states, it is not quantitatively accurate in the description of these kinds of memristors and in the investigation of their circuit applications. This paper introduces the Generalized Boundary Condition Memristor (GBCM) model, preserving the features of the BCM model while allowing, further, an ad‐hoc tuning of activation‐based dynamics, which enables an appropriate modulation of the conditions under which memristors may operate as storage elements or data processors. A simple circuit implementation of the novel model is presented, and time‐efficient simulations confirming the improvement in modeling accuracy over the BCM model are shown. As a proof‐of‐concept for the suitability of the GBCM model in the exploration of the full potential of memristors in neuromorphic circuits and programmable analog filters, this paper adopts it to model fundamental synaptic rules governing the mechanisms of learning in neural systems and to gain some insight into key issues in the design of a couple of filters. Copyright © 2015 John Wiley & Sons, Ltd.

The design and simulation of a titanium oxide memristor-based programmable analog filter in a simulation program with integrated circuit emphasis

In many communication and signal routing applications, it is desirable to have a programmable analog filter. According to this practical demand, we consider the titanium oxide memristor, which is a kind of nano-scale electron device with low power dissipation and nonvolatile memory. Such characteristics could be suitable for designing the desired filter. However, both the non-analytical relation between the memristance and the charges that pass through it, and the changeable V—I characteristics in physical tests make it difficult to accurately set the memristance to the target value. In this paper, the conductive mechanism of the memristor is analyzed, a method of continuously programming the memristance is proposed and simulated in a simulation program with integrated circuit emphasis, and its feasibility and compatibility, both in simulations and physical realizations, are demonstrated. This method is then utilized in a first-order active filter as an example to show its applications in programmable filters. This work also provides a practical tool for utilizing memristors as resistance programmable devices.

On the design of a reconfigurable OTA-C filter for software radio

This paper presents a novel approach to the design of integrated reconfigurable and programmable analog filters for commercial mobile applications. The method is described in the specific context of an analog filter which is capable of operating in b

A 3-Tap FIR Filter With Cascaded Distributed Tap Amplifiers for Equalization Up to 40 Gb/s in 0.18-<tex>$mu$</tex>m CMOS

This paper describes a 3-tap finite impulse response programmable analog filter in 0.18-mum CMOS. The filter is intended for polarization-mode dispersion compensation in 40-Gb/s long-haul single-mode optical fiber links. A novel filter topology is employed, whereby each tap gain comprises a cascade of two distributed amplifiers with adjustable gain. The same lumped LC ladders that provide the 25-ps tap delays also serve as artificial transmission lines for the distributed tap amplifiers. The prototype is 1 mm times 1 mm (900 mumtimes600 mum active area) and consumes up to 70 mW from a 1.8-V supply depending on the tap gains. Linear equalization is demonstrated over a channel with 17 dB of loss at 20 GHz. A 50 mV per side eye amplitude with 14 dB signal-to-noise ratio is demonstrated at 30 Gb/s, and a modest 39 mV per side eye amplitude with 10 dB signal-to-noise ratio is achieved at 40 Gb/s

Time-scaled electrical networks. Properties and applications in the design of programmable analog filters

In this paper, we discuss the properties of time-scaled electrical networks. Two specific ways of implementing scaled linear networks, constant conductance scaling and constant-capacitance scaling, are reviewed along with their noise properties. We then extend time scaling to nonlinear networks. We show that constant-capacitance scaled networks are optimal with respect to noise and dynamic range, irrespective of the scaling factor.