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The charge-generating sensors are widely used in many applications in consumer, automotive and medical electronics. They generate a charge proportional to the applied input quantity: pressure, temperature, acceleration, strain, light, etc. Usually, charge amplifiers are used to register such signals. The charge amplifier is an integrator that integrates the input current over time. In continuous-time signal processing, a parallel resistor is used to dissipate the energy stored on the integration capacitor, and such self-zeroed integrator circuits are known as lossy integrators. To achieve low-frequency operation, when a capacitor is in the picofarad range, a very high-ohmic resistor, in the range of gigaohms, must be used. Such a high-ohmic resistor increases the output offset voltage to an unacceptable level. To overcome the output offset problems, a composite charge amplifier has been recently introduced. This paper presents an innovative lossy integrator readout circuit which contains only one opamp in the feedback. The circuit can be easily adapted to the needed gain and cut-off frequency. Its operation is validated by experimental results. The sufficiently low high-pass cut-off frequency allows the circuit to be used for biosignal amplification. Heart and respiration rates can be easily recorded with piezoelectric sensors attached to the wrist or lung wall. The presented circuit can benefit many applications where charge-to-voltage conversion is needed.

This paper presents a ScAlN/AlN-based MEMS piezoelectric accelerometer using the trapezoidal with corners (TWC) shaped cantilevers. The composite Sc0.2Al0.8N/AlN piezoelectric film is deposited on a silicon-on-insulator (SOI) substrate to improve the sensitivity of the piezoelectric accelerometer. The theoretical and FEM model is established to analyze the relationship between the cantilever stiffness and the piezoelectric parameters on the sensitivity and resonance frequency. The fabricated accelerometer includes a trapezoidal part, a rectangular part, and a silicon proof mass. The experimental results show that the sensitivity, minimum detectable signal (MDS), resolution, and resonant frequency of the proposed TWC shaped accelerometer are 7.95 mV/g, 1 mg, 1 mg, and 1290 Hz, respectively. The manufactured accelerometer exhibits good linearity up to 2 g (non-linearity ${T}=300$ K), the thermal noise of the fabricated accelerometer is lower than 94.7 nV/ $\surd $ Hz. Meanwhile, the charge amplifier circuit noise is about $1.97~\mu \text{V}/\surd $ Hz. The proposed TWC accelerometer is sensitive and suitable to sense vibration acceleration in low-frequency scenarios.

Liquid xenon time projection chamber (LXe TPC) is widely used in high-energy physics experiments such as particle detection and neutrino (or neutrinoless) double beta decay. The charge readout accuracy of the LXe TPC directly affects the measurement results and success of the experiments. Because liquid xenon needs to maintain a cryogenic temperature between 162 and 165 K at atmospheric pressure, the charge generated in the LXe TPC always needs to be read out in the cryogenic environment for minimizing the input capacitance, which has effect in determining the output noise of the charge amplifier. Design a charge readout electronics system applicable to LXe TPC and research a data analysis method to get the exact amount of charge by analyzing the waveform at that output of the designed electronics system. Design a multi-channel charge-reading application specific integrated circuit (ASIC) that can operate in the cryogenic environment. The signals and power supply of the ASIC are connected to an electronics system at room temperature through micro-coaxial cables. The electronics at room temperature complete the sampling of the ASIC output. A data acquisition device receives the sampled waveform data and calculates the charge measurement resolution by Gaussian fitting. The designed ASIC and selected micro-coaxial cable can work in stable condition under the cryogenic environment of 165 K. The analyzed integral nonlinearity of the charge measurement of the chip is 0.83% in the range from 1 to 50 fC, and the charge measurement resolution of the chip is lower than 900 $$\hbox {e}^-$$ RMS. In this paper, a preliminary study of the charge readout method based on the system structure of self-developed ASIC, micro-coaxial cable, and data readout electronics is completed for LXe TPC. The system test results indicate that the designed ASIC can work normally in the cryogenic temperature of 165 K with a high dynamic range and good linearity of the charge measurement. Further work can be done to reduce the charge measurement resolution of the system to 200 $$\hbox {e}^-$$ RMS.

Piezo-electric sensors have found widespread application today due to their ability to provide an interface between the mechanical and electronic world. For humans, in order to interact with these materials, we require an electronic interface. This paper describes one of the possible interfaces, which includes a charge amplifier cascaded with a filter circuit to obtain the frequency response. A novel circuitry consisting of a rectifier and comparator is used to identify the activated channels of the array of piezoelectric sensor. This signal conditioning circuit makes use of active devices such as op amps and nonlinear devices such as diodes along with passive components. The novel circuitry is designed for 2 channels, and demonstrates the logic of selection of these based on the signal parameters. This concept can be extended to any number of channels.

We have developed a real-time dose monitoring system for a low-energy ion-beam facility. Before we developed the monitoring system, the system had given a substantial error of ±23% when we irradiated an ion beam with a dose as much as 3.0 × 1016 cm−2 on the Si substrate. Moreover, a low irradiation dose as small as 1013 cm−2 was scarcely able to be controlled because of a too short irradiation time of several seconds, producing a greater dose error. To develop a real-time dose monitoring system, in this work, we employed a current integrator in conjunction with a beam stopper, by which a dose of 3.0 ×1016 cm−2 can be exactly irradiated on the sample with less than ±6% error, which was ensured by the measurements of Rutherford backscattering spectroscopy.

The circuit structure and the experimental performance of a newly integrated multichannel charge-sensitive preamplifier for silicon or germanium detectors are shown. The circuit has been conceived and optimized for the silicon detector GAL-TRACE, employed for light and heavy ion spectroscopy in nuclear physics experiments. The chip includes four channels optimized for anodic signals and one channel specifically designed for cathodic signals. An I2C interface is used to adjust, as needed, a host of key parameters of the preamplifier, such as sensitivity and bandwidth. An integrated range booster yields an exceptional dynamic range of 103 dB for the cathodic channel. The circuit features a low power consumption of 11 mW per channel, a fast rise time of the order of 10 ns, and low noise. Thanks to an accurate design of the input stage, the equivalent noise charge, measured with a commercial shaping amplifier, is as low as 130 rms electrons at a shaping time of 6 $\mu \text{s}$ with 5 pF of detector capacitance. The bandwidth of the preampifier is adequate for pulse shape analysis techniques used for particle discrimination.

The article presents the results of the development of a system for measuring emittance characteristics of ion sources studied at the IAP NAS of Ukraine with the aim of obtaining the ion beams with a high brightness. The emittance measurement system is based on the scheme of an electrostatic scanner and consists of two main parts: the scanner, which moves in the direction perpendicular to the beam axis using a stepper motor, and the electronic system of control, processing and data acquisition. The electronic system contains a Raspberry pi 3B microcomputer, precision DAC/ADCs, the high-voltage amplifier of a scanning voltage up to ±500 V on deflection plates of the scanner and a wide range current integrator. The determination of the emittance consists in measuring the ion beam intensity distribution when the scanner moves along the x-coordinate and the electrostatic scanning along the x´ angle. The obtained two-dimensional data array allows determining the main characteristics of ion beam: geometric 90% emittance, the root mean square (rms) emittance, the Twiss parameters and phase ellipse of rms emittance, the beam current profile and the angle current density distribution. To test the performance and functionality of the system, the emittance characteristics of the penning type ion source were measured. The working gas was helium, and the beam energy varied within 7–15 keV. At 13 keV of beam energy the following emittances of the He+ ions beam was obtained: 90% emittance is 30 π∙mm∙mrad, rms emittance is 8.4 mm∙mrad, and the normalized rms emittance is equal to 0.022 mm∙mrad. The developed system for measuring the emittance of the ion beams is characterized by a short measurement time of 10-15 minutes.

In this study, we examine the feasibility of designing a MEMS microphone employing a levitation based electrode configuration. This electrode scheme enables capacitive MEMS sensors that could work for large bias voltages without pull-in failure. Our experiments and simulations indicate that it is possible to create robust sensors properly working at high DC voltages, which is not feasible for most of the conventional parallel plate electrode-based-microscale devices. In addition, the use of larger bias voltages will improve signal-to-noise ratios in MEMS sensors because it increases the signal relative to the noise in read-out circuits. This study presents the design, fabrication, and testing of a capacitive microphone, which is made of approximately 2 μm thick highly-doped polysilicon as a diaphragm. It has approximately 1 mm 2 surface area and incorporates interdigitated sensing electrodes on three of its sides. Right underneath these moving electrodes, there are fixed fingers being held at the same voltage potential as the moving electrodes and separated from them with a 2 μm thick air gap. The electronic output is obtained using a charge amplifier. Measured results obtained on three different microphone chips using bias voltages up to 200 volts indicate that pull-in failure is completely avoided. The sensitivity of this initial design was measured to be 16.1 mV/Pa at 200 V bias voltage, and the bandwidth was from 100 Hz to 4.9 kHz.

The charge amplifier is an important building block in various electronic circuits. In this paper a new charge amplifier for piezoelectric sensors is introduced. The advantages of the new proposed charge amplifier becomes obvious in the quasi-static applications. In some quasi-static applications the traditional charge amplifiers uses an extremely large feedback resistor (in the range of $\text{G}\Omega $ ) whereas the proposed charge amplifier no longer requires such extremely large resistors. Moreover the proposed circuit reduces the output offset voltage significantly in comparison with conventional charge amplifier. The proposed circuit can be also implemented by using general purpose JFET operational amplifiers instead of using electrometer operational amplifiers therefore the cost of implementation will be reduced significantly in comparison with conventional charge amplifier. The proposed charge amplifier was assembled by using general purpose JFET Op-Amp to capture and amplify the output voltage of the piezoelectric vibration sensor Minisense100. In this experiment the low-cutoff frequency and the gain of the proposed charge amplifier were set equal to 0.2Hz and 20.5 dB respectively. The output offset voltage of the circuit was measured equal to 210 $\mu \text{V}$ .The measurement of very small vibration (±0.015g) showed a relative error equal to 2.1% with respect to the value which is obtained by using vibration meter as reference.

We present the fabrication and characterization of an array of microbridge-structured magnetoelectric (ME) thin film sensors which are constructed by an ME composite consisting of a 1 $\mu \text{m}$ PZT film and a 1 $\mu \text{m}$ amorphous FeCoSiB film deposited on a partially thinned Si substrate. Characterization of the sensor showed a large ME coefficient of $16.87~\text {V/cm}\cdot \text {Oe}$ in resonance at 7.9 kHz without a charge amplifier. The sensitivity was enhanced by 1.65 times when three identical sensors were connected in series. The resonant frequency of the sensor was precisely regulated by adjusting the etched area of the substrate, and the 3 dB bandwidth of the resonant frequency was doubled after two adjusted sensors were connected in parallel.

This paper presents the updates implemented by the Vibration Laboratory of INMETRO on the electrical calibration of charge conditioning amplifiers. We can now carry out both standard classical calibrations with fixed in-series capacitors and including an adjustable parallel capacitance to match the total capacitance of a given pair of accelerometer plus cable. The calibration system and some analysis of measurement results are presented.

Parameters such as capacitance and conductivity are measured to describe the properties of a medium, including its moisture content. These methods do not deliver highly accurate results in materials that are characterized by low homogeneity, varied porosity, high conductivity and high water content. This study proposes a more accurate method for estimating the parameters of any medium. In the experimental setup, a charge amplifier and a phase-sensitive voltmeter were applied to determine resistance and capacitance parameters of a medium based on the signals received by the measuring system. The proposed method can be applied to non-homogeneous media containing both dielectric and conductive materials. The described measuring system is composed of two flat electrodes whose size can be adapted to the dimensions of the analyzed medium. A method for processing the sensing signal to determine the impedance characteristics of a medium with the use of a phase-sensitive voltmeter was described. The measuring system was modeled in Matlab/Simulink, and the results were discussed.

In this paper, a low noise and low power analog front end for piezoelectric microphones used in hearing aid devices is presented. It consists of a Charge Amplifier, followed by a Variable Gain Amplifier and an Analog-to-Digital Converter. At the core of charge amplifier a two stage opamp with modified cascode current mirror is designed which achieves a gain of 93 dB and phase margin of 62°. Designed analog front end achieves an input referred noise of 0.12 μVrms and SNR of 74 dB. It consumes power of 430 μW from 1.8 V supply and occupies an area of 1.2 mm × 0.22 mm. Proposed circuit is designed and fabricated in 0.18 μm CMOS process. Designed circuit is interfaced with a sensor model of piezoelectric microphone, which mimics Ormia ochracea's auditory system, and its performance is successfully verified against simulation results.

A charge amplifier with noise peaking suppression and gain drop compensation is proposed. By utilizing the proposed Quasi-Miller RC network, the noise peaking is suppressed and gain drop is compensated, which alleviates the design trade-off between charge gain and output root-mean-square (RMS) noise, therefore obtains an improved sensitivity. Meanwhile, the Quasi-Miller RC network permits the charge amplifier to support ultra-low frequency operation without using a huge resistor, which is normally required by the charge amplifier. The fabricated charge amplifier demonstrates an input-referred RMS noise charge of 909 aC, a charge gain of 10.2 V/pC and a 3-dB bandwidth from 80 Hz to 38 MHz. Low noise and high charge gain are obtained simultaneously. Meanwhile, extremely low cut-off frequency is also obtained, which is beneficial to maintain the signal integrity.

This paper presents a differential-input, differen tial-output charge amplifier topology built with discrete, commercial components. The amplifier is designed to interface high-impedance ultrasonic sensors made of piezoelectric polymer, with a required bandpass of at least 100 kHz to 1 MHz, and needs to operate from a single 5-V supply. The performance and tradeoffs of the proposed topology are evaluated analytically and using a circuit simulator, showing a charge-to-voltage conversion gain in excess of 240 dB[V/C], while maintaining an input impedance lower than 100 $\Omega$ . Simulations and measurements of a prototype implementation are presented.

This paper presents a motion-sensing device with the capability of harvesting energy from low-frequency motion activities that can be utilized for long-term human health monitoring. The energy harvester used in the proposed motion sensor is based on the mechanical modulation of liquid on an insulated electrode, which utilizes a technique referred to as reverse electrowetting-on-dielectric (REWOD). The generated AC signal from the REWOD is rectified to a DC voltage using a Schottky diode-based rectifier and boosted subsequently with the help of a linear charge-pump circuit and a low-dropout regulator (LDO). The constant DC voltage from the LDO (1.8 V) powers the motion-sensing read-out circuitry, which converts the generated charge into a proportional output voltage using a charge amplifier. After amplification of the motion data, a 5-bit SAR-ADC (successive-approximation register ADC) digitizes the signal to be transmitted to a remote receiver. Both the CMOS energy harvester circuit including the rectifier, the charge-pump circuit, the LDO, and the read-out circuit including the charge amplifier, and the ADC is designed in the standard 180 nm CMOS technology. The amplified amplitude goes up to 1.76 V at 10 Hz motion frequency, following linearity with respect to the frequency. The generated DC voltage from the REWOD after the rectifier and the charge-pump is found to be 2.4 V, having the voltage conversion ratio (VCR) as 32.65% at 10 Hz of motion frequency. The power conversion efficiency (PCE) of the rectifier is simulated as high as 68.57% at 10 Hz. The LDO provides the power supply voltage of 1.8 V to the read-out circuit. The energy harvester demonstrates a linear relationship between the frequency of motion and the generated output power, making it suitable as a self-powered wearable motion sensor.

Charge amplifiers, characterized by their charge-sensitivity or charge gain, are essential components of a transducer-interfacing system that amplify charge signals emerging from various sensors and convert them into voltage signals. Today, with increased scaling of MOSFETs, it becomes challenging to obtain the charge amplifiers with high charge sensitivity and low power. Furthermore, if the charge amplifier is to be operated at lower bandwidth, then obtaining low noise at higher charge sensitivity is also difficult. In this paper, the authors propose a novel design of a charge-sensitive preamplifier in 90 nm CMOS technology that can be operated at the frequency range of 10 Hz-10 kHz, suitable for biosignals at lower frequencies. The opamp in the preamplifier is designed to have a folded-cascode structure with composite cascoding at its input transistors for low power operation. A feedback resistance of 185.20 GΩ for the preamplifier is actively realized using long-channel cascode MOSFET stage in the opamp, thereby eliminating the need for a large value of passive resistance on-chip. The preamplifier has a high charge sensitivity of 8.875 mV/fC at a low power consumption of 214.32 nW with input-referred noise of 256.89 μV for the bandwidth 10 Hz-10 kHz. The preamplifier operation is verified by interfacing the model of the preamplifier with the small-signal equivalent of a SPICE model of a Silicon Nanowire Field-effect Transistor (SiNW-FET) based biosensor which was proposed for impedimetric sensing of biomolecules.

Monitoring human health in real-time using wearable and implantable electronics (WIE) has become one of the most promising and rapidly growing technologies in the healthcare industry. In general, these electronics are powered by batteries that require periodic replacement and maintenance over their lifetime. To prolong the operation of these electronics, they should have zero post-installation maintenance. On this front, various energy harvesting technologies to generate electrical energy from ambient energy sources have been researched. Many energy harvesters currently available are limited by their power output and energy densities. With the miniaturization of wearable and implantable electronics, the size of the harvesters must be miniaturized accordingly in order to increase the energy density of the harvesters. Additionally, many of the energy harvesters also suffer from limited operational parameters such as resonance frequency and variable input signals. In this work, low frequency motion energy harvesting based on reverse electrowetting-ondielectric (REWOD) is examined using perforated high surface area electrodes with 38 µm pore diameters. Total available surface area per planar area was 8.36 cm2 showing a significant surface area enhancement from planar to porous electrodes and proportional increase in AC voltage density from our previous work. In REWOD energy harvesting, high surface area electrodes significantly increase the capacitance and hence the power density. An AC peak-to-peak voltage generation from the electrode in the range from 1.57-3.32 V for the given frequency range of 1-5 Hz with 0.5 Hz step is demonstrated. In addition, the unconditioned power generated from the harvester is converted to a DC power using a commercial off-theshelf Schottky diode-based voltage multiplier and low dropout regulator (LDO) such that the sensors that use this technology could be fully self-powered. The produced charge is then converted to a proportional voltage by using a commercial charge amplifier to record the features of the motion activities. A transceiver radio is also used to transmit the digitized data from the amplifier and the built-in analog-to-digital converter (ADC) in the micro-controller. This paper proposes the energy harvester acting as a self-powered motion sensor for different physical activities for wearable and wireless healthcare devices.

This paper presents a reverse electrowetting-on-dielectric (REWOD) energy harvester integrated with rectifier, boost converter, and charge amplifier that is, without bias voltage, capable of powering wearable sensors for monitoring human health in real-time. REWOD has been demonstrated to effectively generate electrical current at a low frequency range (< 3 Hz), which is the frequency range for various human activities such as walking, running, etc. However, the current generated from the REWOD without external bias source is insufficient to power such motion sensors. In this work, to eventually implement a fully self-powered motion sensor, we demonstrate a novel bias-free REWOD AC generation and then rectify, boost, and amplify the signal using commercial components. The unconditioned REWOD output of 95–240 mV AC is generated using a 50 μL droplet of 0.5M NaCl electrolyte and 2.5 mm of electrode displacement from an oscillation frequency range of 1–3 Hz. A seven-stage rectifier using Schottky diodes having a forward voltage drop of 135–240 mV and a forward current of 1 mA converts the generated AC signal to DC voltage. ∼3 V DC is measured at the boost converter output, proving the system could function as a self-powered motion sensor. Additionally, a linear relationship of output DC voltage with respect to frequency and displacement demonstrates the potential of this REWOD energy harvester to function as a self-powered wearable motion sensor.

This paper presents a self-powered motion sensor based on reverse-electrowetting on dielectric (REWOD) energy harvesting having the capability of remotely keeping a track of any motion activity. The energy harvester includes a rectifier and a voltage regulator to provide the DC supply voltage to the analog front-end and the transmitter to wirelessly transfer the data from the motion sensor. The on-chip circuitry includes a seven-stage voltage-doubler based rectifier, an amplifier, an analog-to-digital converter (ADC), and a transmitter, and is designed in standard 180 nm CMOS process with a supply voltage of 1.8 V. The recycled folded cascode (RFC) based charge amplifier has a closed-loop gain of 53 dB within the bandwidth of 1–150 Hz, which is suitable to detect any low-frequency motion signal. An 8-bit SAR-ADC is designed to digitize the amplified signal with a sampling rate of 1 ksamples/s. The transmitter used for this application operates in the 3.1–5 GHz frequency band with an energy efficiency of 8.5 pJ/pulse at 100 kbps data rate. The wireless motion sensing device with the REWOD can be suitable for quantitatively monitoring the motion-related data as a wearable sensor.

A detector connected to a charge amplifier adds parasitic input capacitance that alters the amplifier's gain. The detector capacitance therefore must be characterized so as to properly account for its effect. This paper presents a novel, compact technique to measure the detector capacitance by exploiting the circuit elements within the charge amplifier itself. Reconfiguring the charge amplifier with programmable switches, a capacitor divider network emerges to measure the detector capacitance without the need for any accurate timing references and complex controls. Experimental results of the proposed charge amplifier fabricated in a 180-nm CMOS technology demonstrate the ability to measure the detector capacitance to within 3% of its actual value. An actual charge measurement is also presented.

The paper theoretically determines the dependence of the electrically excited noise, damped oscillations piezoelectric sensor, integrated with SWCNT (single-wall carbon nanotube) needle and charge amplifier, from defects of an SWCNT graphene sheet and sensor malfunctions generally, for AFM (atomic force microscopy) with high-resolution. Also is the proposed method for estimating the piezoelectric sensor state, integrated with the SWCNT needle and charge amplifier when evaluating “SWCNT needle-surface” contact in real-time scanning AFM. Many micro-machining techniques have been employed to fabricate signal oscillations piezoelectric sensors and piezoelectric nanoactuators. The properties of SWCNT, for example, high strength, many times greater than the strength of steel, makes them suitable elements for use as needles probe microscopy. This paper presents both experimental and analytical data to show the critical characteristics of a piezoelectric sensor, integrated with SWCNT needle contact in the real-time scanning AFM.

PolyVinyliDene Fluoride (PVDF) energy harvesters have been observed to possess the ability to detect leak and damage in pipes they are bonded to by monitoring their vibration energy harvested due to fluid flow, measured as open circuit voltage. Consequently, they can be employed as structural health monitoring (SHM) sensors for such applications. To make this energy harvesting based SHM an effective measurement methodology, the harvested energy should be demonstrably passed through a piezoelectric measuring chain and the results obtained should be calibrated appropriately. This paper addresses this problem by designing a custom-made three-channel dual-stage charge amplifier as signal conditioner and validating the measuring chain. The charge amplifier ensures that the voltage generated by the PVDF harvester is measured accurately and remains proportional to the strain responses for the monitored structure and constitutes a part of the piezoelectric measuring chain. A two-stage validation process was employed in this work. The first stage is a general validation exercise serving as a check for measuring chain intrinsic noise and general performance while the second stage is an application-specific validation exercise that serves to estimate the performance of the measuring chain for the target application. The suitability of using the measuring chain for the application of vibration energy harvesting based SHM is demonstrated through the result of this validation process.

As today’s smartphone displays become thinner, the coupling capacitance between the display electrodes and touch screen panel (TSP) electrodes is increasing significantly. The increased capacitance easily introduces time-varying display signals into the TSP, deteriorating the touch performance. In this research, we demonstrate that the maximum peak display noise in the time domain is approximately 30% of the maximum voltage difference of the display grayscale through analysis of the structure and operation of displays. Then, to mitigate display noise, we propose a circuit solution that uses a fully differential charge amplifier with an input dynamic range wider than the maximum peak of the display noise. A test chip was fabricated using a 0.35 μm CMOS process and achieved a signal-to-noise ratio of 41 dB for a 6-mm-diameter metal pillar touch when display pulses with 5-V swing were driven at 100 kHz.

We present the development of a test ASIC, named Timespot1, designed in CMOS 28-nm technology, featuring a 32x32 pixel matrix and a pitch of 55 μm, The ASIC is conceived as the first prototype in a series, capable to read-out pixels with timing capabilities in the range of 30 ps and below. Each pixel is endowed with a charge amplifier, a discriminator and a Time-to-Digital-Converter, capable of time resolutions below 20 ps and read-out rates (per pixel) around 3 MHz. The timing performance are obtained respecting a power budget of about 50 µW per pixel, corresponding to a power density of approximately 2 W/cm2• This feature makes the Timespot1 approach an interesting solution for vertex detectors of the next generation of colliders, where high space and time resolutions will be mandatory requirements to cope with the huge amount of tracks per event to be detected and processed.

With the advanced technologies such as 5 G network and internet of things (IoT), there are incredibly increasing sensors and corresponding applications emerging to benefit our daily lives. However, the power supplies for countless sensors become a serious issue to suppress further expansion of IoT. In this work, a self-powered triboelectric sensor (CN-STS) made of electrospun composite nanofibers is developed towards smart traffic monitoring and management. To meet the requirements of fast-response and high sensitivity for the smart traffic management, transferred charge density is adopted as sensing signals compared to voltage / current outputs for it can perfectly record the subtle differences and suitable for dynamic traffic monitoring. Carbon nanotube is further doped into PVDF nanofibers to improve the electrical output performance and pressure sensitivity. A relatively high sensitivity of 0.0406 μ Cm-2kPa-1 at low pressure range (0 to 75 kPa) and a sensitivity of 0.0032 μ Cm-2kPa-1 at higher pressure range (75 to 425 kPa) can be achieved by the CN-STS, indicating that the CN-STS is more sensitive at low pressure range. Moreover, by connecting to cloud IoT services, the functions of traffic flow management, overlapping and speeding vehicle capturing, and plate number recognition are realized by the CN-STS arrays with a compensation circuit. A charge amplifier is utilized in power management to process the charge input signals for better distinguishing the signals from none-vehicles and stabilize the volage output for further reading by the A/D convertor build in Raspberry Pi. The engineered self-powered triboelectric sensors not only open a new potential area for triboelectric nanogenerators but also significantly popularize the IoT industry.

A digital closed-loop system design of a microelectromechanical systems (MEMS) disk resonator gyroscope (DRG) is proposed in this paper. Vibration models with non-ideal factors are provided based on the structure characteristics and operation mode of the sensing element. The DRG operates in force balance mode with four control loops. A closed self-excited loop realizes stable vibration amplitude on the basis of peak detection technology and phase control loop. Force-to-rebalance technology is employed for the closed sense loop. A high-frequency carrier loaded on an anchor weakens the effect of parasitic capacitances coupling. The signal detected by the charge amplifier is demodulated and converted into a digital output for subsequent processing. Considering compatibility with digital circuits and output precision demands, a low passband sigma-delta (&Sigma, &Delta, ) analog-to-digital converter (ADC) is implemented with a 111.8dB signal-to-noise ratio (SNR). The analog front-end and digital closed self-excited loop is manufactured with a standard 0.35 &micro, m complementary metal-oxide-semiconductor (CMOS) technology. The experimental results show a bias instability of 2.1 &deg, /h and a nonlinearity of 0.035% over the &plusmn, 400&deg, full-scale range.

We report the characterisation and calibration of a new laser pulse energy measurement device, developed for pico-joule pulse energy measurement at repetition rates up to 1 kHz. The device comprises a charge integration amplifier operating in conjunction with an input charge source; a light trapping photo-detector, which converts an incident laser pulse to a charge pulse. The novel amplifier individually integrates each charge pulse from the source and outputs a corresponding 20-bit resolution digital signal. This signal is converted to pulse energy through post processing, knowing the absolute responsivity of the photodiode detector and the calibration factors of the charge amplifier. A differential evolution algorithm is used to determine optimised values for the feedback capacitors of the amplifier, the amplifier gain and offset. The values measured by the new laser pulse energy meter were compared with those obtained from measurements traceable to both the high and low-level laser pulse energy scales maintained by NIST, Boulder. These were consistent within the combined expanded measurement uncertainty. This new device offers lower uncertainty and portability, suitable for field use.

This study is dedicated to design an in-cell active-matrix capacitive (IAMC) touch panel and its readout circuitry. This IAMC touch panel is in a structure that embeds all components for touch panel in a standard active matrix display. In this way, the thickness of the display-touch combined module can be significantly reduced, but introducing much noise from display to touch module, leading to higher mis-judgements on touches. To solve the problem, this study proposes a new readout circuit and digital signal processing techniques to tackle well the aforementioned noise for much accurate touch sensing. The readout consists essentially of an analog front-end switched capacitor charge amplifier (SCCA), a 12-bit SAR ADC and a digital signal processing (DSP) unit for calibration and filtering. A field-programmable gate array (FPGA) board is adopted to implement the designed digital signal processing in practice. The performance of the readout is tested for a 5 × 12, 0.88-inch IAMC touch panel with a scanning frequency of 200 Hz. Experimental data show clearly that the sensed capacitance was successfully converted to 200 digits in a full dynamic range of 12-bits and a SNR of 52 dB, which facilitates well accurate determination of touches and locations on an IAMC touch panel.

A model of a High Voltage CMOS (HV-CMOS) Monolithic Active Pixel Sensor (MAPS) has been modelled using Technology Computer Aided Design (TCAD). The model has incorporated both the active region and the on-pixel readout circuits which were comprised of a source follower amplifier and an integrated charge amplifier. The simulation has examined the electrical characteristics and response output of a HV-CMOS MAPS sensor using typical dimensions, levels of doping in the structural layers and bias conditions for this sensor. The performance of two alternate designs of amplifier have been examined as a function of the operating parameters. The response of the sensor to the incidence of Minimum Ionizing Particles (MIPs) at different energies has been included in the model.

Розглянуто питання щодо вибору оптимальної схемотехнічної моделі біморфного п'єзо-елемента динамічних тисків з двоконтуровим від'ємним зворотним зв'язком та досліджено характеристики п'єзоперетворювачів з вихідним підсилювачем заряду та підсилювачем напру- ги в додатковому каналі зворотного зв'язку. Issues related to the selection of the optimized circuit model of a bimorph piezoelectric element of dynamic pressure with dual-circuit inverse feedback are reviewed. Characteristics of piezoelectric transducers with source charge amplifier and voltage amplifier in additional feedback path are investigated.

This paper is concerned with the experimental characterization of a charge sensitive amplifier featuring dynamic signal compression, fast recovery time, low noise, and reduced area occupancy. The device takes the advantage of the nonlinear characteristic of a feedback transistor that behaves like a voltage-controlled capacitance. This property has been exploited to fit a wide input dynamic range into the available output swing. The charge amplifier can be operated in synchronous mode at high frame rates, of the order of few megahertz, thanks to a wide bandwidth, an improved output stage, and a fast reset network. Thanks to the small area occupancy, the amplifier is suitable for integration in a $100\times 100\,\,\mu \text {m}^{2}$ pixel area. All these features make the device a good candidate for applications where a fast front end with a nonlinear response is required, such as in imaging instrumentation for free electron laser experiments. The aim of this paper is to present and discuss the experimental results coming from the characterization of the first prototype of the circuit, which has been designed in a 65-nm CMOS technology. This paper has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare, Italy.

In this paper, we have proposed an input interfacing scheme with differential output for integrated capacitive sensor applications. In the proposed scheme, the front-end interfacing is based on switched capacitor charge amplifier configuration using a fully differential operational transconductance amplifier and one differential capacitive sensor arrangement which provides differential output with minimum number of circuit components. In the back end, a sigma–delta ( $\Sigma \Delta $ ) modulator is integrated for modulated digital output. The signal conditioning circuit also includes gain programmability by selecting proper feedback capacitor and mismatch cancellation between the sensing capacitors through on-chip capacitors array. The complete application specific integrated circuit (ASIC) is designed and fabricated in United Microelectronics Corporation (UMC) $0.18-\mu \text{m}$ CMOS process technology. The fabricated ASIC is then integrated with a silicon-on-insulator microelectromechnical systems capacitive accelerometer to test and characterize the performance of the proposed scheme. The measured result shows that the sensitivity of the proposed circuit can be varied from 200 to 900 mV/g by changing the feedback capacitor. The integrated system is also tested with electrostatic actuation as well as with a vibrating shaker and the measurement results are presented.

An improved topology for the baseband super-regenerative sampling amplifier is proposed and analyzed, which employs a series-capacitors output load to realize positive feedback. As in the conventional circuit, the gain of the amplifier is continuously variable by controlling the length of the capacitor charging phase. It is shown that decreasing feedback enhances the linearity of the circuit while trading off with a lower sampling speed. Entirely removing the feedback yields the integrating amplifier circuit. This is a practical implementation in terms of linearity, power, noise, and gain in low-frequency applications, including biomedical signal amplification. The analysis is verified by measured results from an integrated circuit prototype in 180-nm CMOS technology.

A comprehensive noise model of a junction gate field-effect transistor (JFET) charge amplifier is presented for applications with piezoelectric sensors. Based on this previously reported amplifier structure, a noise equivalent circuit is derived and discussed. Universal noise gain expressions for each of the twelve considered noise sources are given. By means of an analytical description of the charge amplifier’s noise behavior, the design and optimization of such preamplifiers for various capacitive microelectromechanical sensor systems will be distinctly simplified. Calculations of the noise floor are compared with measurements with a cantilever-type magnetoelectric sensor and with the performance of a so far commonly utilized basic charge amplifier. With the JFET charge amplifier a noise reduction of approximately 22 dB is achieved in the vicinity of the utilized sensor’s resonance frequency of 7.45 kHz. The reported amplifier is the first which has no negative influence on the total noise level of a resonant magnetoelectric sensor system.

In this study, we successfully developed a high signal-to-noise ratio (SNR) rangefinder based on a piezoelectric micromachined ultrasonic transducer (pMUT). A c-axis-oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) epitaxial thin film was employed as a piezoelectric transducer considering its outstanding figures-of-merit for SNR, due to the high piezoelectric coefficient and small relative permittivity (typical values: e31,f = −14C/m2, er = 200–300). The pMUTs was based on an epitaxial PMnN-PZT/Si diaphragm structure and prototyped from a SOI substrate; its rangefinding ability was evaluated with a pair of devices, specifically, transmitter and receiver, respectively. As a result, the maximum range was estimated to be over 2 m at a low actuating voltage of 1 Vp-p, when 12 dB was set as the threshold SNR. The energy consumption of the transmitter was as small as ∼5 nJ for the generation of a 50-cycle ultrasonic burst. The noise analysis of the receiver’s charge amplifier circuit indicated that this system could be improved by the optimization of bandwidth and by eliminating external noise. We believe that this high performance pMUT rangefinder will be utilized in various applications of consumer electronics or as an alternative to the bulk piezoelectric ceramic rangefinder in the near future.

Integrators are an important functional module of several filters, PID controllers and automated systems. Designing these integrators in fractional domain enhance their operations and make the responses highly precise and accurate. This paper presents a Fractional Order Current Integrator using second generation current conveyor as the active block, and fractional capacitor as a grounded fractance. Analog realization of this fractance comprises of resistances and capacitances arranged in parallel RC ladder topology. The motivation behind this work is that more accurate and stable fractional integrator with fewer passive elements, for lower bias voltage and high dynamic range, can be designed and implemented. Integrators of fractional orders from 0.1 to 0.9 are simulated using TSMC 0.25 µm technology parameters. The transient and frequency responses obtained in Mentor Graphics are in close conformity with the theoretical values of magnitude and phase. Robustness of the proposed model is verified by performing Monte Carlo analysis in time and in frequency domain. Comparisons of fractional order current integrators with existing analog fractance models have also been included to further validate the work presented in the paper.

In this paper, a new tomography technique called electrical charge tomography for two-phase flow imaging is presented. The probe consists of few pair of electrodes which are electrically energized to generate electrical charges within the fluid under test. The intensity of these charges depends on the chemical and physical properties of the fluid, as well as to its molecular distribution. Another group of electrodes surrounding the cross section of the fluid under test are used to capture the induced electrical charges. These are then converted into an electrical signal using a high sensitive charge amplifier. A postprocessing unit which consists of an analog to digital converter, followed by an field programmable gate array (FPGA) module is then used for high level signal processing (i.e., a dedicated dynamic thresholding algorithm) and image reconstruction. Experimental results demonstrate the capability of the system to accurately generate 2-D cross-sectional images, where the error is lower by up to 14% when using another electrical capacitance (ECT) tomography probe. The other advantage of this technique over ECT is the reduced data acquisition time, since in ECT a minimum time is required for the charge and discharge of the capacitance in order to achieve acceptable accuracy. This makes the probe another attractive concept for future tomography systems targeting real-time applications.

The development of a DC magnetic field sensor based on a magnetoelectric (ME) PVDF/Metglas composite is reported. The ME sensing composite has a resonance frequency close to 25.4 kHz, a linear response (r2=0.997) in the 0-2Oe DC magnetic field range and a maximum output voltage of 112 mV (related to a ME voltage coefficient α33 of ≈30 V.cm-1.Oe-1). By incorporating a charge amplifier, an AC-RMS converter and a microcontroller on chip peripheric analog to digital converter (ADC) the ME voltage response is not distorted, the linearity is maintained and the ME output voltage increases to 3.3V (α33effective=1000 V.cm-1.Oe-1). The sensing device, including the readout electronics, has maximum drift of 0.12 Oe with an average total drift of 0.04 Oe, with a sensitivity of 1.5 V.Oe-1 (15 kV.T-1) and a 70nT resolution. This features compares favourably with a reference Hall sensor that showed a maximum drift of 0.07 Oe and an average error of 0.16 Oe, 5 V.T-1 sensitivity and 2 μT resolution. Those features allied to the accurate measurement of the HDC fields in the 0-2 Oe range make this polymer-based device very attractive for applications such as Earth magnetic field sensing, digital compasses, navigation and magnetic field anomaly detectors, among others., Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 under Project PTDC/EEI-SII/5582/2014, and in part by the Basque Government In- dustry Department under the ELKARTEK Program. The work of P. Mar- tins, V. Correia, S. Reis, and M. P. Silva was supported by the FCT under Grant SFRH/BPD/96227/2013, Grant SFRH/BPD/97739/2013, Grant SFRH/BDE/406, and Grant SFRH/BD/70303/2010. The work of S. Lanceros-Mendez was supported in part by the Provincial Council of Bizkaia under the Bizkaia Talent Program, in part by the European Union’s Seventh Framework Program, and in part by the Marie Curie Actions, info:eu-repo/semantics/publishedVersion

This article provides insight into the development of a powerful and low-cost chopper amplifier for piezoelectric pressure sensors and shows its possible applications for injection moulding machines. With a power supply of 3.3 volts and the use of standard components, a circuit is introduced which can be connected to a commercially available microcontroller without any additional effort. This amplifier is specialised for low frequencies and high-pressure environments. With the adjustment of the sample and chopper frequency by means of software, the amplifier can easily be adapted for other applications. This chopper amplifier is a very compact and cost-effective solution with a small number of required components. In this contribution, it will be shown that the amplifier has good results in various laboratory tests as well as in the production process. Furthermore, an approach to fuse data from force and pressure signals by using a Kalman filter will be presented. With this method, the quality of the sensor signals can be significantly improved. This article is an extension of our previous work in Schneider et al. (2016b).

In this work, we propose a method to increase the parasitic input resistance caused by application of chopper modulation to indirect current feedback instrumentation amplifiers. The result is obtained by applying dynamic element matching to the input and feedback ports at the same frequency as chopper modulation. The proposed approach requires effective offset ripple rejection and equalization of the input and feedback common mode voltages. An in-amp architecture that meets both requirements and embodies the proposed input resistance boosting method is described. Experimental verification is provided by means of a prototype designed and fabricated using the $0.32~\mu \text {m}$ CMOS devices of the STMicroelectronics BCD6s process. The amplifier operates with a 3.3 V supply voltage and a total current absorption of $170~\mu \text {A}$ . An input impedance in excess of $1~\text {G}\Omega $ has been measured at a chopper frequency of 20 kHz. The input referred voltage noise density is 18 nV/sqrt(Hz) with a flicker corner of 0.2 Hz and 200 Hz bandwidth.

This paper describes the design of a 25 Gb/s energy-efficient CMOS optical receiver with high input sensitivity. By incorporating a current-boosting preamplifier with a dual-path time-interleaved integrating-type optical receiver, it provides 1:2 demultiplexing operation with a tolerance to lower bandwidth photodiodes. The bandwidth of current amplifier is chosen as $0.35\times $ operating data rate for maximizing the receiver signal-to-noise ratio. Experimental results show that the receiver can achieve 25 Gb/s operation when integrated with a 9 or 17 GHz GaAs photodiode. Input sensitivities in the two cases are -7.2 dBm (w/i a 9 GHz photodiode) and -10.8 dBm (w/i a 17 GHz photodiode), respectively, for a bit error rate of less than $10^{-12}$ . In addition, a single-tap decision-feedback equalizer (DFE) is embedded to compensate photodiode bandwidth and improve input sensitivity. Integrated with a low-cost 9 GHz photodiode, the input sensitivity and timing margin of the receiver are improved by 2 dB and 0.25 UI, respectively, after DFE compensation. By utilizing a current integrator and time-interleaved comparators, its energy efficiency is 1.13 pJ/b at 25 Gb/s under a 1.2 V power supply. Fabricated in a 40 nm bulk-CMOS technology, the core circuit occupies a chip area of 0.007 mm 2 only.

A new series-parallel switched capacitor converter topology capable of operating off two independent input sources and generating target output voltage in buck or boost mode is presented. Operation principle, conversion ratios, modelling considerations in different operation modes and extensive loss analysis are derived. The converter is robust and may be operated off one or two input sources, having the ability to change conversion ratio over a wide range. The proposed model assumes that the conduction losses are proportional to the average current flowing through each of the charge pump capacitor in a switching phase. Capacitor current instantaneous waveform in the complete charge, partial charge and no charge modes are captured in simulation and experiment. Model predicted equivalent resistance, output voltage and instantaneous capacitor current waveform concur excellent with simulated and experimental values, rendering the new converter as an excellent candidate for two and single input source applications.

The measurement of the operating deflection shape (ODS) of power transmission belts is of great importance for the fault diagnosis and prognosis of industrial belt drive systems. This paper presents a novel method based on an electrostatic sensor array to measure the ODS of a belt moving both axially and transversely. The electrostatic sensor integrates a charge amplifier that converts the induced charge on a strip-shaped electrode into a voltage signal. Finite-element simulations are performed to study the sensing characteristics of the sensor and the results reveal that the sensor can respond to vibration displacement. Construction of the ODS is achieved in the frequency domain using the ODS frequency response function. Comparative experimental studies with a high-accuracy laser displacement sensor were conducted on a purpose-built test rig and the results show that the vibration frequencies and their relative magnitudes obtained from both sensors agree well with each other. Experiments conducted over a range of belt axial speeds show that the belt vibrates at frequencies that are well separated and identifiable using a peak picking method. The measured ODSs of the first three vibration modes illustrate that the vibration displacement is larger in the middle of the belt span than at both ends and that the phase shift relative to the reference sensor at each measurement point increases monotonically along the belt running direction. The belt axial speed determines the vibration frequencies and displacement, which reaches the maximum amplitude around the natural frequency of the belt.

This paper presents an alternative implementation of a chopper-modulated current-mode instrumentation amplifier. The structure provides very low-offset voltage at the output due to chopper modulation and residual offset removal path. The residual offset removal path is based on low-pass filtering using grounded capacitances which provides compact design structure compared to various chopper-modulated instrumentation amplifier designs. Rail-to-rail input common-mode range is possible due to transmission gate-based input chopper switching scheme. The design is made using a 0.35-µm CMOS process with ±1.65 V supply voltage. The area of the amplifier is 234µm × 344 µm, including all the filtering elements. The proposed circuit with residual offset removal path provides less than 1 µV input referred offset voltage. The advantage of the proposed instrumentation amplifier is its large bandwidth, simple design scheme and compact area compared to chopper-modulated voltage mode amplifiers.

In this paper, we investigate the responsivities and output voltage noise power spectral densities of magnetoelectric (ME) laminate sensors, consisting of length magnetized Terfenol-D alloys and transverse/width poled Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMNT) crystals (i.e. L-T mode and L-W mode respectively), which are directly integrated with custom-build low noise charge amplifier circuits. Both the theoretical analyses and experimental results prove that the L-W mode sensor with the optimized polarized direction of the PMNT plate possesses lower magnetic detection limit at the interested high frequency range of 10 kHz≤ f ≤50 kHz. The equivalent magnetic noise ( EMN ) of the L-W mode sensor is 0.78 pT/Hz 1/2 at 30 kHz, which is about 1.7 times lower than the 1.35 pT/Hz 1/2 for conventional L-T mode sensor. Furthermore, an effective method of using operational amplifiers with low equivalent input noise voltage and employing ME laminate composites with high voltage coefficient to reduce the EMN s of the ME laminate sensors at high frequency range has been established.

International audience; Next generation pixel chips at the High-Luminosity (HL) LHC will be exposed to extremely high levels of radiation and particle rates. In the so-called Phase II upgrade, ATLAS and CMS will need a completely new tracker detector, complying with the very demanding operating conditions and the delivered luminosity (up to 5×10 34 cm −2 s −1 in the next decade). This work is concerned with the design of a synchronous analog processor with zero dead time developed in a 65 nm CMOS technology, conceived for pixel detectors at the HL-LHC experiment upgrades. It includes a low noise, fast charge sensitive amplifier featuring a detector leakage compensation circuit, and a compact, single ended comparator that guarantees very good performance in terms of channel-to-channel dispersion of threshold without needing any pixel-level trimming. A flash ADC is exploited for digital conversion immediately after the charge amplifier. A thorough discussion on the design of the charge amplifier and the comparator is provided along with an exhaustive set of simulation results.

Flexible interdigital transducers fabricated with piezopolymer film are applied for SHM of composite material with guided waves at frequency below 1 MHz. This type of transducers has high impedance respect to piezoceramic equivalents and suffer of signal degradation due to stray capacitances and common mode noise. The interfacing with electronic systems has been improved by using a custom designed charge amplifier and described in this work.

We have considered results of SiPM analog interface schematic design on array chip MH2XA030. The SiPM includes current buffer, current integrator and base level recovery (BLR) circuit. We have described analog interface operation for this type of sensor in details, specified electrical circuit and computer simulation results.

Sample deposition based on micro-droplet ejection has broad application prospects in the field of biomedicine. Ejection of RPMI-1640 culture medium (without cells) is investigated experimentally using a home-build electrohydrodynamic (EHD) ejection system, consisting of a liquid supplier and a nozzle, a voltage source, a droplet collector, and a supplemented photoelectric monitoring module. Electric voltage is applied between the nozzle and the droplet collector. The liquid surface is electrically charged and the ejection takes place when electric force overcomes the surface tension. At appropriate voltages, uniform ejection states are established with ejection frequency ranging from a few to a few tens of Hertz. Monitoring of the ejection process is performed by two methods. The ejection process can be recorded by a high speed camera, and then analysed by image processing. Using output signal of a charge amplifying circuit as a reference, a single shot camera is controlled to capture images at certain delays, and the entire process of the droplet ejection can be recorded. Experiments have shown that when the liquid meniscus breaks up, the output signal of the charge amplifier reaches the maximum.