Resistor-capacitor Filter Research Articles

Fabrication of RC filters from a single printed Zn layer by reactive inkjet printing

This paper presents the development of planar zinc (Zn) resistor–capacitor (RC) filters from a single printed layer that are both printed and treated at room temperature. The fabrication process involves screen printing the resistor, capacitor and interconnects in a single patterned layer on kraft paper substrates using a Zn microparticle ink. In order to form a distinct resistor and capacitor in the patterned structure, reactive inkjet printing (RIJ) was performed to selectively dispense acetic acid on the RC filter pattern to achieve regions with highly contrasting resistance. The required high degree of spatial contrast was achieved using the positional control of the inkjet printer combined with the number of print passes and drop spacing used to dispense the acetic acid droplets. X-ray diffraction and scanning electron microscopy showed the crystal structure and grain size of Zn microparticles remained unchanged with increasing acetic acid exposure while the prominence of cold-welding increased with increasing exposure. Zn-based RC filters sharing a common set of dimensions but with a wide range of corner frequencies were successfully fabricated using this process. For a fixed filter geometry, the corner frequencies could be tuned from ∼7 kHz to ∼1 MHz as the number of print passes used to form the resistor increased in a stepwise manner. To the best of our knowledge, this is the first room temperature printing process to produce side-by-side resistors and conductors from the same printed layer and the first printing process of any type to produce RC filters with such a wide range of corner frequencies.

Causes and Solutions for the Mal-operation of Differential Pressure Protection of Substation

The capacitor compensation circuit of the traction substation is affected by high-harmonics and the differential voltage protection is frequently mal-operation, which causes serious disturbance to the railroad transportation order. In this paper, the effect of parasitic inductance of capacitor banks and the parameter characteristics under high harmonics are analyzed by establishing the high-frequency circuit structure of capacitor banks. Then, a fitting formula describing the differential voltage is established based on the measured data to describe the frequency variation characteristics of the differential voltage value. Finally, a solution to the problem of differential voltage protection mal-operation of capacitor banks is discussed, a Resistance-Capacitance filter circuit is designed, and the effectiveness is verified by simulation.

Configuration of suppression schemes against high-frequency transient reignition overvoltages caused by shunt reactor switching-off in offshore wind farms

It is crucial to protect offshore wind farms from overvoltages because of bad accessibility and high maintenance costs. During the process of switching-off a shunt reactor with a 40.5 kV vacuum circuit breaker, high-steepness reignition overvoltages may occur. In order to reproduce this reignition overvoltage accurately and further determine a suitable mitigation scheme, this paper proposes a new quantitative evaluation framework, which comprehensively considers its magnitude and steepness. Firstly, main component models of a typical offshore wind farm are developed in PSCAD/EMTDC, which consider their high-frequency transient characteristics. Subsequently, the transient characteristics of reignition overvoltages at the 35 kV side of shunt reactors are analyzed. Then, for the sake of investigating the mitigation performance of different overvoltage protective schemes, a quantitative evaluation is conducted. Simulation results show that switching-off shunt reactors in offshore wind farms can cause high-frequency transient reignition overvoltages characterized by a high amplitude and a high steepness at its terminals. It is found that a resistor-capacitor filter or a new scheme combining a surge arrester with a smart choke can be installed on the terminals of shunt reactors to decrease both the magnitude and the steepness of reignition overvoltages.

RC Filter Design for Wireless Power Transfer: A Fourier Series Approach

In this letter, we study the impact of the low-pass resistor-capacitor (RC) filter on radio frequency (RF) wireless power transfer (WPT). The RC filter influences both the RF bandwidth by removing the harmonics as well as the ripple voltage at the output of the rectifier. In particular, a large (small) RC time constant, reduces (increases) the ripple but decreases (enhances) the direct-current (DC) component. By following a Fourier series approach, we obtain closed-form expressions for the rectifier's output voltage, the RC filter's output as well as the DC voltage. Our analytical framework provides a complete characterization of the RC filter's impact on the WPT performance. We show that this complete and tractable analytical framework is suitable for the proper design of the RC filter in WPT systems.

Active bandwidth control of external-cavity system for improving mode-hop-free synchronous tuning characteristics of an external-cavity diode laser

The mode-hop-free (MHF) tuning range and wavelength tuning rate are two critical characteristics for an external-cavity diode laser (ECDL). On the premise of stable dynamic response of the external-cavity system inherent in the ECDL, a wide MHF tuning range can be guaranteed by using the synchronous tuning principle. However, when high-frequency tuning, the mechanical vibration of the external-cavity system is excited due to limited system bandwidth, which will break the mode-matching of the internal and external-cavity and greatly decrease the MHF tuning range. Therefore, the system bandwidth of the external-cavity limits the tuning frequency and thus the wavelength tuning rate. In order to obtain a wide MHF range at high-frequency tuning, we used an active bandwidth control method with a resistance-capacitance (RC) filter to increase the system bandwidth and suppress the dynamic vibration of the external-cavity. With the RC filter, the system bandwidth of the external-cavity was increased from 290 rad/s to 5012 rad/s, an improvement of 17 times. The experimental results indicated that the MHF range at high-frequency tuning was significantly improved and a maximum wavelength tuning rate of 18.6 THz/s was obtained at tuning frequency of 100 Hz.

Self-aligned inkjet printing of resistors and low-pass resistor–capacitor filters on roll-to-roll imprinted plastics with resistances ranging from 10 to 106 Ω

Resistors are essential and ubiquitous building blocks in electronic circuits. Fabrication of printed resistors in a manner compatible with roll-to-roll printing is important for realizing low-cost and high-throughput production of electronic devices. Here we present fully printed resistors fabricated via a novel self-aligned printing method, termed self-aligned capillarity-assisted lithography for electronics (SCALE). Flexible substrates with imprinted features such as reservoirs and capillary channels were prepared by roll-to-roll processing. Functional inks were then delivered sequentially into the reservoirs by inkjet printing and the ink flowed spontaneously into the adjoining channels driven by capillarity. Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) was used as the resistive material, and silver was used for the electrodes. Using SCALE, we achieved fully inkjet-printed, self-aligned resistors with resistance values ranging over five orders of magnitude while keeping the overall dimensions of the devices constant. We then employed SCALE to build low-pass resistor–capacitor filters with cutoff frequency from 0.4 to 27 kHz and excellent operational stability. Overall, this work expands the potential of self-aligned inkjet printing for producing fully printed electronic circuits.

Tunable resistivity in ink-jet printed electrical structures on paper by plasma conversion of particle-free, stabilizer-free silver inks

Printable metal inks are typically composed of premade nanoparticles that require postdeposition thermal sintering to produce crystalline, electrically conductive features. In this paper, it is shown that particle-free Ag inks made from simple, water-soluble metal salts such as silver nitrate can be ink-jet printed and converted into electrical features with tunable resistivity at low temperature (<100 °C) by exposure to a pure argon plasma. X-ray diffraction confirms that the converted inks are crystalline, and four-point probe electrical measurements show that the sheet resistances are a function of the pressure and power in the plasma. From cross-sectional scanning electron microscopy analysis, it is found that the morphology of the converted silver layer becomes increasingly dense with increasing plasma treatment time, which explains the measured changes in sheet resistance, and that the thickness of the layer is ∼1.5 μm, which yields a minimum resistivity of ∼6 × 10−8 Ω m, approximately 3.8 times higher than bulk resistivity of silver. Interestingly, the resistivity can be varied over a span of 6 orders of magnitude which allows resistor–capacitor filter devices to be fabricated exhibiting varying cut-off frequencies from a single material and geometry.

Printed Graphene Derivative Circuits as Passive Electrical Filters.

The objective of this study is to inkjet print resistor-capacitor (RC) low pass electrical filters, using a novel water-based cellulose graphene ink, and compare the voltage-frequency and transient behavior to equivalent circuits constructed from discrete passive components. The synthesized non-toxic graphene-carboxymethyl cellulose (G-CMC) ink is deposited on mechanically flexible polyimide substrates using a customized printer that dispenses functionalized aqueous solutions. The design of the printed first-order and second-order low-pass RC filters incorporate resistive traces and interdigitated capacitors. Low pass filter characteristics, such as time constant, cut-off frequency and roll-off rate, are determined for comparative analysis. Experiments demonstrate that for low frequency applications (<100 kHz) the printed graphene derivative circuits performed as well as the circuits constructed from discrete resistors and capacitors for both low pass filter and RC integrator applications. The impact of mechanical stress due to bending on the electrical performance of the flexible printed circuits is also investigated.

Sample-and-Hold Inputs for Minimum-Phase Behavior of Nonminimum-Phase Systems

The advantages of minimum-phase (MP) systems for control applications are well known. Prior research has shown that a non-MP (NMP) system can be discretized to an MP system using either a zero-order hold (ZOH) or a square-pulse sample-and-hold input (SHI). This paper investigates the MP characteristics of the discrete-time (DT) system obtained by discretizing a continuous-time single-input single-output NMP system using different SHIs. Two new SHIs (forward and backward triangular) are studied in addition to the square pulse. Numerical simulations were adopted for studying the MP property of the resulting DT system as a function of sample-and-hold parameters. The simulation results show that it is possible to find a smaller sampling period that results in an MP DT system using the proposed SHIs compared with the ZOH. The $q$ -Markov cover system identification with pseudorandom binary signal was then used for a hardware-in-the-loop (HIL) simulation study. A resistor–capacitor filter was used to represent the implementation error of the SHI due to unmodeled actuator dynamics. The HIL simulation results show that the proposed SHI scheme is robust to actuator modeling error. The MP properties of the DT systems with three SHIs are compared. The results show that the forward triangle SHI has the best performance due to its robustness to unmodeled actuator dynamics and the capability of retaining the MP property of the discretized system at small sampling periods.

Wavelet packets based denoising method for measurement domain repeat-time multipath filtering in GPS static high-precision positioning

Repeatable satellite orbits can be used for multipath mitigation in GPS-based deformation monitoring and other high-precision GPS applications that involve continuous observation with static antennas. Multipath signals at a static station repeat when the GPS constellation repeats given the same site environment. Repeat-time multipath filtering techniques need noise reduction methods to remove the white noise in carrier phase measurement residuals in order to retrieve the carrier phase multipath corrections for the next day. We propose a generic and robust three-level wavelet packets based denoising method for repeat-time-based carrier phase multipath filtering in relative positioning; the method does not need tuning to work with different data sets. The proposed denoising method is tested rigorously and compared with two other denoising methods. Three rooftop data sets collected at the University of Nottingham Ningbo China and two data sets collected at three Southern California Integrated GPS Network high-rate stations are used in the performance assessment. Test results of the wavelet packets denoising method are compared with the results of the resistor–capacitor (RC) low-pass filter and the single-level discrete wavelet transform (DWT) denoising method. Multipath mitigation efficiency in carrier phase measurement domain is shown by spectrum analysis of two selected satellites in two data sets. The positioning performance of the repeat-time-based multipath filtering techniques is assessed. The results show that the performance of the three noise reduction techniques is about 1–46 % improvement on positioning accuracy when compared with no multipath filtering. The statistical results show that the wavelet packets based denoising method is always better than the RC filter by 2–4 %, and better than the DWT method by 6–15 %. These results suggest that the proposed wavelet packets based denoising method is better than both the DWT method and the relatively simple RC low-pass filter for noise reduction in multipath filtering. However, the wavelet packets based denoising method is not significantly better than the RC filter.

Solvent-free fabrication of paper based all-carbon disposable multifunctional sensors and passive electronic circuits

In light of recent interest in the green fabrication of electronics, we report eco-friendly engineered temperature sensors, pH sensors, humidity sensors and passive resistor–capacitor (RC) filters by solvent-free processing of graphite on cellulose paper. This was achieved via direct writing of graphite pencil on cellulose paper which involves the deposition of few layers to multi layers of conductive graphene flakes intercalated by clay and wax. The temperature sensor exhibits a negative temperature coefficient of resistance of −4232 ppm K−1, which is comparable to that of conventional temperature sensors (platinum, nickel, and copper) that are fabricated by capital intensive and complex procedures. The dynamic response of the temperature sensor shows its repeatability with excellent response time of 13.5 s. The all-carbon pH sensor could efficiently distinguish acidic, alkaline and neutral solutions with significant sensitivity from 1.77 kΩ pH−1 to 2.21 kΩ pH−1. The higher sensitivity of the pH sensor is attributed to the oxygen functional groups present in pencil graphite which undergoes protonation and deprotonation in presence of H+ and OH− ions to alter the conductivity of graphite trace. The interdigitated capacitive humidity sensor shows a linear response to humidity with fast response (1.5–2 s) and recovery times (6–7 s). These fast response and recovery times are due to fast adsorption and evaporation kinetics of water molecules on polar OH groups of cellulose fibers in paper, which depends on porosity of the paper. The versatility of the pencil-on-paper approach was further explored by drawing resistor and interdigitated capacitor in series to fabricate in-plane all-carbon RC filter which demonstrate anticipated functionality with a cut-off frequency of 6 kHz. To the best of our knowledge, no studies have been reported on direct-write graphite on paper based in-plane all carbon passive electronic circuits, pH sensor and humidity sensor. This cleanroom-free approach further expands the scope of graphite on paper as a functional material in developing sensors and circuits for greener consumer electronics thereby causing no environmental contamination either in their production or disposal.

Event-Based Protection Scheme for a Multiterminal Hybrid DC Power System

In this paper, we investigate an event-based protection scheme for a multiterminal dc power system, which includes hybrid energy resources and various loading schemes. The proposed protection scheme transfers less data when compared with commonly used data-based protection methods, and does not require high-speed communication and synchronization. Each protection unit is able to autonomously identify the type of event using the current derivative fault identification method, employing an artificial inductive line impedance. In order to accurately set the protection relays, detailed fault current analysis considering low pass resistor capacitor filter effects are presented. The decision for fault isolation is made based on the unit judgment and the data received through high-level data communication from other interconnected units. The performance of the proposed protection scheme was evaluated under different dc feeder and bus faults. The results show that this scheme is able to accurately identify the type of fault, isolate the faulted area, and restore the system quickly while limiting the load voltage drop to its preset limit.

An Electrical Inspection of the Subsurface Cisternae of the Outer Hair Cell

The cylindrical outer hair cell (OHC) of Corti’s organ drives cochlear amplification by a voltage-dependent activation of the molecular motor, prestin (SLC26a5), in the cell’s lateral membrane. The voltage-dependent nature of this process leads to the troublesome observation that the membrane resistor-capacitor filter could limit high-frequency acoustic activation of the motor. Based on cable theory, the unique 30 nm width compartment (the extracisternal space, ECS) formed between the cell’s lateral membrane and adjacent subsurface cisternae (SSC) could further limit the influence of receptor currents on lateral membrane voltage. Here, we use dual perforated/whole-cell and loose patch clamp on isolated OHCs to sequentially record currents resulting from excitation at apical, middle, and basal loose patch sites before and after perforated patch rupture. We find that timing of currents is fast and uniform before whole-cell pipette washout, suggesting little voltage attenuation along the length of the lateral membrane. Prior treatment with salicylate, a disrupter of the SSC, confirms the influence of the SSC on current spread. Finally, a cable model of the OHC, which can match our data, indicates that the SSC poses a minimal barrier to current flow across it, thereby facilitating rapid delivery of voltage excitation to the prestin-embedded lateral membrane.

Quasi-linear vacancy dynamics modeling and circuit analysis of the bipolar memristor.

The quasi-linear transport equation is investigated for modeling the bipolar memory resistor. The solution accommodates vacancy and circuit level perspectives on memristance. For the first time in literature the component resistors that constitute the contemporary dual variable resistor circuit model are quantified using vacancy parameters and derived from a governing partial differential equation. The model describes known memristor dynamics even as it generates new insight about vacancy migration, bottlenecks to switching speed and elucidates subtle relationships between switching resistance range and device parameters. The model is shown to comply with Chua's generalized equations for the memristor. Independent experimental results are used throughout, to validate the insights obtained from the model. The paper concludes by implementing a memristor-capacitor filter and compares its performance to a reference resistor-capacitor filter to demonstrate that the model is usable for practical circuit analysis.

Field effect transistors and RC filters from pencil-trace on paper

We report the fabrication of Resistor-Capacitor (RC) filters and field effect transistors (FETs) based on pencil drawings on paper, which contain turbostratic graphite crystallites as evidenced from Raman analysis. Pencil drawings have been employed as resistor and an ion gel, 1-butyl-3-methylimidazolium octyl sulfate mixed with polydimethylsiloxane (PDMS) as dielectric, for the fabrication of RC filters with a cut-off frequency of 9 kHz. With ion gel as gate dielectric, an ambipolar electric field effect has been obtained from the pencil-trace at low operating voltages. The carrier mobilities were found to be ∼106 and 59 cm(2) V(-1) s(-1) for holes and electrons, respectively. The mobility value showed only 15% variation among the devices tested, truly remarkable given the simplicity of the fabrication process.

Control of a fractional chaotic system based on a fractional-order resistor—capacitor filter

We present a new fractional-order resistor—capacitor controller and a novel control method based on the fractional-order controller to control an arbitrary three-dimensional fractional chaotic system. The proposed control method is simple, robust, and theoretically rigorous, and its anti-noise performance is satisfactory. Numerical simulations are given for several fractional chaotic systems to verify the effectiveness and the universality of the proposed control method.

A liquid drop RC filter apparatus for detection

A new analytical detector based on a liquid drop resistor-capacitor (RC) filter is described, in which transformed gain vs. frequency curves are used to analyze compounds. This detector can be used to detect either charged or neutral species (that are dielectrically different) which are dissolved in a liquid (e.g., water, alcohol, solvent mixtures, etc.). This device was fabricated by modifying an electrowetting on dielectric (EWOD)-based experimental setup. When a liquid drop is placed on a dielectric surface, the system acts as a RC filter. At a given frequency, gain is a function of conductivity, surface tension, dielectric constant, double-layer thickness of the solid-liquid drop interface, as well as the applied voltage. Since different liquids and solutions have different physical properties, each liquid/solution has a unique curve (peak) in gain vs. frequency plot. This is the basic principle behind the detector. Different amounts of zinc chloride dissolved in water, benzalkonium chloride in water, 1-methylimidazole in water, cetyltrimethyl-ammonium chloride (CTAC) in water, and CTAC dissolved in ethylene glycol solutions were tested with the detector as proof of principle. The device can be used as a stand-alone detector or can easily be coupled with droplet based microfluidic lab-on-a-chip systems such as EWOD-based microfluidic chips.

Sampling and Reconstruction of Zero-Order Hold Signals by Parallel RC Filters

In this work we describe a reconstruction algorithm for zero-order hold (ZOH) waveforms measured by a parallel sam-pling scheme. In the method the ZOH signal is fed to a parallel network consisting of resistor-capacitor (RC) filters, whose outputs are sampled simultaneously. The algorithm reconstructs N previous samples of the input signal from output samples of N parallel RC circuits. The method is especially useful in sampling and reconstruction of the ZOH signals produced by the digital-to-analog converters. Using the parallel sampling method the sampling rate of the analog-to-digital converters can be increased by a factor of N. We discuss a variety of applications such as reconstruction of ZOH pulse sequences produced by ultra wide band (UWB) transmitters.

Filters for optimal smoothing of acoustic and electric blink reflex EMG responses to determine blink response magnitude

The functional (i.e., kinematic) aspects of the blink reflex depend on the size of the integrated orbicularis oculi EMG response. Peak amplitude of smoothed rectified EMG is often used as an approximation of integrated EMG. A comparison was made between the outputs of 24 different smoothing filters, correlating peak amplitude of acoustic or electric blink reflexes with integrated EMG. The coefficient of determination ( R 2) was largest (i.e., ≥.95 for acoustic and ≥.90 for electric blink reflexes) when using either (1) a first-order resistor–capacitor filter with a time constant of 50 or 100 ms, (2) a boxcar filter averaging 51 or 101 data points, or (3) an unequal-weight finite impulse response filter with a cutoff frequency of 5 or 10 Hz. These filters are thus recommended when determining peak amplitude. Applying a baseline correction on peak amplitude and integrated EMG produced slightly smaller values of R 2 compared with uncorrected measures.

Current-mode operational transconductance amplifier-capacitor biquad filter structures based on Tarmy–Ghausi Active-RC filter and second-order digital all-pass filters

The Tarmy-Ghausi (TG) active resistor-capacitor (RC) filters using op-amps and its modification by Moschytz are well known to active RC filter designers. These use first-order all-pass networks in a negative feedback loop. New current-mode universal operational transconductance amplifier-capacitor (OTA-C) biquad filters based on the TG active RC filter are considered here. These are based on a recently proposed OTA-C based first-order all-pass network. Three different feedback arrangements are investigated in the proposed filter structure so as to reduce the pole-Q sensitivity. The proposed biquad filters are shown to implement all different types of filters like low-pass, high-pass, band-pass, symmetric notch, all-pass, low-pass notch and high-pass notch. The synthesis of the general biquad is carried out in a novel way by invoking the analogy with direct-form digital filter structures. The special case of all-pass filter realisation derived from the proposed universal filter needs additional hardware for realising the feed-forward coefficients. Hence alternative OTA-C based all-pass filter implementations based on Mitra-Hirano and Gray-Markel second-order digital filter structures are derived in which the coefficients that are used to realise the denominator are shared in the realisation of numerator also. All the proposed circuits are compared with the other structures available in the literature. The simulation results of the proposed circuits are also presented.