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The potential of smart aggregate for seismic stress monitoring has been identified, but only moderate dynamic stress of relatively high frequency can be measured reliably due to the limitations of conventional charge amplifiers. To improve the performance of smart aggregate-based monitoring systems, a charge amplifier was designed especially for the demands of seismic stress monitoring. Its performance was tested in the low frequency range down to 0.05 Hz with high charge input up to 2 × 107 pC representing stress up to 100 MPa by feeding it frequency-sweep charge signals. With the specially designed amplifier, the performance of the smart aggregate-based monitoring system was tested in both frequency-sweep and amplitude-sweep loading tests, and the influence of lead zirconate titanate depolarization was evaluated at static loads of 4.8, 14.4, and 24 MPa. The results show that the demands of seismic monitoring with a smart aggregate-based system can be satisfied, and that the sensitivity of the system remains constant under dynamic loads up to at least 45 MPa.

This paper proposes an accurate tunable-gain 1/x circuit. The output voltage of the 1/x circuit is generated by using a capacitor-charging time that is inversely proportional to the input voltage. The output voltage is independent of the process parameters because the output voltage depends on the ratios of the capacitors, resistors, and current mirrors. The voltage gain of the 1/x circuit is tuned by an 10-bit digital code. The 1/x circuit was fabricated using a 0.1 8μm CMOS process . Its core area is 0.011m m 2 (144μm×78μm) and it consumes 278μW at VDD=1.8V and fCLK=1MHz. Its error is within 1. 7% at VIN=0.05~1V.

A wide input range, compliant with electrochemical amperometric and voltammetric sensors analog-front-end (AFE) integrated circuit (IC) is proposed. The AFE employs current integrator (CI) and trans-impedance amplifier (TIA) to deal with the input current in the order of nA and µA separately, achieving the advantage of high dynamic range and high resolution. Input voltage is converted to current through a series of precise resistances, and detected by CI or TIA, which making the input voltage range is not limited by the power supply. An incremental sigma-delta ADC is employed to digitize the transferring signal, reducing the complexity and power dissipation. Compared to other alternatives, the AFE could handle current and voltage signals simultaneously, and input voltage range is not limited by power supply, showing high dynamic range and resolution. The AFE IC is fabricated in 0.18µm 1P5M mixed-signal CMOS process, occupies an area of 3.2mmi?2mm, the readout circuit has a dynamic range of 120dB, consumes 4.2mA. The AFE IC present in this manuscript employs dual-path, current integrator (CI) and trans-impedance amplifier (TIA), to deal with the input current in the order of nA and µA separately, achieving the advantage of high dynamic range and high resolution.The AFE IC can be compliant with both electrochemical amperometric and voltammetric sensors, instead of traditional instrument amplifier, a voltage-to-current circuit is adopted to convert an input voltage to a current, making the input voltage range is not limited by the power supply.Instead of a traditional sigma-delta ADC, a incremental sigma-delta ADC is employed to digitize the transferring signal, reducing the complexity and power dissipation, providing the feature of one-to-one mapping between input and output.

A mutual-capacitive touch-sensor read-out integrated circuit (ROIC) with a differential sensing scheme is proposed to reduce the driving pulse amplitude of touch sensor panel (TSP) down to 0.4 V. This reduction is achieved by mitigating the effect of the liquid crystal display (LCD) common-voltage (VCOM) noise, which is time periodic. To accomplish this mitigation, the TSP driving pulse (VSTM) is synchronized to the gate-driver-pulse generating signal (GCLK) of LCD, and its frequency is set to (2n + 1) times the frequency of GCLK, where n is a non-negative integer. The repetition period TN of the VCOM noise is one half of the GCLK period. A receiver channel consists of a charge amplifier, a chopper, and an integrator; all are in differential circuits. The chopper is driven by the VSTM. The integration period of the integrator is set to 2T N to suppress the periodic LCD noise. A referenceless clock and data recovery circuit are used to generate VSTM from GCLK continuously with time in spite of the discontinuity of GCLK during the vertical blanking period. The proposed ROIC fabricated in a 0.35-μm CMOS was applied to a 6.9 in 12 × 16 TSP located on a rather noisy 23 in in-plane switching LCD monitor. The measured signal-to-noise ratio changes from 27 to 9 dB as the VSTM amplitude changes from 3.3 to 0.4 V, where the GCLK frequency is 16.8 kHz and the VSTM frequency is 352.8 kHz. The reporting rate of the ROIC is 175 Hz.

This study presents a reduced state feedback sliding-mode current controller (RSFSMCC) for a voltage source inverter (VSI)-based higher-order circuit. The proposed controller consists of an inner current loop and an outer voltage loop. The reference for the inner input inverter current is generated from the outer voltage loop through a proportional plus integral controller. The stability of the system is ensured by using feedback of only two state variables, that is, input inverter current and output capacitor voltage of the VSI circuit. A reduced state feedback analysis is used to obtain the gain matrix for the higher-order circuit. The tracking control convergence criterion of the system is examined through the eigen values of the resultant state matrix derived for the VSI circuit. The frequency response plot shows that the proposed RSFSMCC is robust with good stability margins. The simulation results show that the output voltage well tracks the reference voltage with reduced steady-state error for both linear and non-linear loads. The simulation results obtained in power systems CAD/electromagnetic transients including DC (PSCAD/EMTDC) v4.2.1 software are verified through the experimental results conducted on a single-phase VSI circuit using field programmable gate array implementation of the RSFSMCC.

BACKGROUND:During the process of cell micro operation, the contact force between the entry needle and the cell membrane is usually a very small area to be tested. OBJECTIVE: These two features have been utilized to design a high precision micro force sensor to provide a force feedback in the process of cell micro operation. METHODS: However, PVDF (Polyvinylidene Fluoride) has continued to display both a wide range of frequency response and a highly sensitive transform between force and electricity. In this paper a charge signal is obtained. In order to transform the charge signal into a voltage signal, a signal processing circuit was designed. The data acquisition card PCI-6221 (National Instruments) was used. It was employed to collect the voltage signal. RESULTS: The resultant micro force sensor was calibrated by using a rating test. CONCLUSIONS: The experimental test results demonstrated that the sensitivity and linearity of the designed micro force sensor were higher than the sensitivity and linearity of a traditional piezoelectric sensor.

A linear front-end electronic system based on a high-speed charge sensitive amplifier and a tunable shaping amplifier suitable for silicon detectors has been presented. The designed charge sensitive amplifier features simplicity and compactness. It is based on the combination of a low-noise field-effect transistor input device and a current feedback opamp ensuring high frequency and small rise time. The circuit provides both an energy signal and a timing signal. The shaping amplifier is a fifth-order complex filter based on an opamp- RC topology providing a nearly Gaussian response. The shaper also includes a pole-zero cancellation circuit and a base line restorer to preclude the pileup of subsequent input signals. A control system has been developed to adjust the main parameters of the channel. The designed readout channel has been optimized for a medium energy range up to 50 MeV coupled to silicon detectors up to 100 pF. Its feasibility for nuclear physics applications has been experimentally validated.

The main research direction of Numerical control lathe cutting force signal on-line monitoring is to process real-time monitoring, using the sensor, charge amplifier, video acquisition card and computer to collect data and signal. Signal acquisition makes use of the piezoelectric sensor signals and send them to the computer in order to acquire the real-time data and display the dynamic signal so that monitor the process. Signal processing is the course that data will be collected for subsequent processing and analyzing. It includes display, filtering, correlation analysis, spectral analysis, etc. We can conclude the signal’s characteristics after the time domain and frequency domain analysis of signals.

The adoption of charge-mode amplification, rather than the classical voltage-mode, to interface piezoelectric interdigital transducers made of polymer film to the data acquisition electronics is described. The circuit and operating principles of a charge amplifier are briefly explained, followed by the experimental comparison of a charge amplifier implementation with a solution based on an instrumentation amplifier. The experiments, based on A 0 -mode Lamb wave transmission over an aluminium plate, demonstrate the effectiveness of charge-mode interfacing and its insensitivity to cable loading.

SEE testing carried out on PADI-X charge amplifier ASIC within ESA-JUICE mission context. Not SEL or permanent damage was detected. Full SEFI/CEM cross sections are provided with an ion LET range of 1-63 MeV.cm2/mg.

The paper presents the radiation test results of a readout ASIC (CASCA: Charge Amplifier with Switched Capacitor Array) for a Time Projection Chamber (TPC). The CASCA integrated 32 channels with full signal processing circuits and was fabricated in 0.18 $\mu {\mathrm{ m}}$ CMOS process. Both Total Ionizing Dose effect (TID), including static TID and dynamic TID and Single Event Effects (SEE) tests, which mainly focus on Single Event Latch-up (SEL), Single Event Upset (SEU) and Single Event Transient (SET) of CASCA were taken. The tests were taken with 200MeV and 62.8MeV protons. The radiation test setup and test results were given and discussed.

Due to its excellent dynamic performance for vibration measurement, MEMS-based piezoelectric accelerometer has been studied in recent years. Piezoelectric micro-accelerometer can be regarded as a component that can produce electric charge with high internal impedance, but the quantity of electric charge is very subtle. By taking this into account, the general measuring circuit does not meet the requirement. In this paper, a charge amplifier with an integrated chip is used instead of a large number of discrete components, and cold-discharge design is also included to decrease the thermal noise of the whole circuit.

This paper describe new tomography acquisition design based on capacitance measurement namely Electrical Capacitance Volume Tomography (ECVT). ECVT is one of measurement instrument which is specifically used in tomography application. The acquisition instruments used 64 electrode capacitive sensors, in cylindrical shape. Measurement of capacitance is performed using charge amplifier circuit on each electrode to convert the current into voltage signal. The resulting signal represented capacitance value. To accommodate the whole 64 electrodes capacitive sensors, two data acquisition systems are developed to handle up to 32 electrodes. We also developed the communication protocol between two data acquisition systems, measured the system performance, and the speed of acquisition data.

This paper presents the modeling and design of a source-buffered Miller operational amplifier structure that is highly immune to electromagnetic interference (EMI). The source-buffered Miller operational amplifier is designed and fabricated in the 0.18 μm mixed-mode CMOS process and modeled mathematically including the body effect and channel length modulation. Measurement results show that the maximum EMI-induced input offset voltage for the source-buffered Miller operational amplifier is 22 mV at 1 GHz, when a 900 mVpp EMI signal is applied at its input. In contrast, the standard Miller operational amplifier generates an input offset voltage of 215 mV under the same operating conditions.

In this paper, an advanced layout scheme of an integrated capacitor is presented which improves the efficiency of a poly-poly capacitor based voltage doubler charge pump. The main losses in voltage doubler charge pumps are mathematically described and the importance of low stray capacitances are discussed. By means of the improved poly-poly capacitor layout, the usable capacitance is increased while the stray capacitance is reduced. To quantify the improvements, a standard charge pump architecture is fabricated in a 0.35 μm CMOS technology with three different capacitor types. The presented measurement results show an efficiency of up to 77.9 % and an improvement by up to 18 % if compared to the same charge pump architecture using a standard capacitor. While following all design rules, the improved poly-poly capacitor layout scheme achieves almost the efficiency of a double metal-metal capacitor which allows typically for the highest efficiency of fully integrated charge pumps.

Manipulation in nano-scale is important to the development of Nano-technology, while position sensing is the base of nano-manipulation. Self-sensing is a method providing true sensor-actuator collocation and especially suitable for room-limited workspace. This paper introduced a self-sensing method for displacement measurement, based on charge amplifier. The principle of self-sensing was derived from piezoelectric constitutive equations, and a charge amplifier circuit was developed to obtain the displacement of piezoelectric stack. A series of experiments were conducted to evaluate the characteristics of our method. The results of the experiments and some characteristics of charge-amplifier based self-sensing method were presented.

This paper reports a low-power low-noise folded-cascode OTA based charge amplifier designed to be used as the front-end amplifier (FEA) for a pyroelectric transducer based respiration monitoring system. The amplifier is designed in 0.5μm standard CMOS process and consumes only 5.4 μW of power with 1.8V supply voltage. The operational transconductance amplifier (OTA) adopts a pseudo-resistor based diode-connected MOSFET in the feedback configuration to achieve a 1 mHz low corner frequency. Measurement results show an FEA input referred noise of only 5.017 μVRMS over the frequency range of 125 mHz to 10 kHz. Test results also include the recording of the respiratory signal acquired by the pyroelectric transducer and the FEA.

The offset of a Miller amplifier is mainly due to an imperfect matching between its inputs. When the input transistors are MOSFETs, the exposure to ionizing radiation affect the threshold voltage of both transistors. With proper polarization, the shift in the threshold voltage impoverishes the matching in the input, increasing the offset. Hence, measuring the change in the offset during irradiation, one can estimate the absorbed radiation dose. In this work, a theoretical analysis is presented in order to establish the effect of ionizing radiation on the different blocks of the Miller amplifier. The design of a Miller amplifier and its fabrication on an integrated circuit for testing is described. The design and assembly of a dedicated hardware and software for data acquisition is also described. First results on the fabricated dosimeter in a 0.6μm commercial CMOS technology show a sensitivity of 60 mV/Gy and a resolution of 4 cGy.

THick Gaseous Electron Multiplier (THGEM) has many advantages while the moderate position resolution is regarded as the main inferiority comparing with the traditional GEM, so this limits the applications of THGEM, such as X-ray imaging and charge particle tracking. By improving the production techniques, THGEMs with smaller pitch and hole diameter can be made, i.e., 0.4 and 0.15 mm by mechanical drilling, and 0.3 and 0.1 mm by laser etching, respectively. Based on the new THGEMs, a two-dimensional imaging detector with 50 $$\times $$ 50mm sensitive area was developed for 0.1 $$\sim $$ 50 MeV low-energy electrons detection and reaching better than 100 $$\upmu $$ m position resolution (sigma). At the same time, a set of front-end electronics was developed based on homemade ASIC chips, i.e., Charge Amplifier and Shaping Amplifier for GEM (CASAGEM), and applied successfully to the detector. The X-ray and beam tests results indicate that both detector and Front End Electronics (FEE) worked well, and the position resolution achieved 74.9 $$\upmu $$ m by using the charge center-of-gravity method. This indicates that the high-position resolution THGEM is promising for imaging and tracking application.

This paper presents the design of a 1024-channel dual-modality CMOS biosensor suitable for both capacitive sensing and impedance spectroscopy. The chip serves as a platform for detection, localization and monitoring of bacteria and can be adopted for affinity-based assays. The chip features a 32×32 array of unpassivated metal electrodes formed on the top metal of a 0.18μm CMOS process, with an overall sensing area of 2.06 mm2. The system design is based on a shared in-pixel integrator that can be used as a charge amplifier for capacitive sensing (CS) or as part of a transimpedance amplifier for electrical impedance spectroscopy (EIS). The CS mode is capable of a operation bandwidth of 50 MHz at a current consumption of 82 μA per pixel. The EIS channel operates over a bandwidth between 100 Hz and 1 MHz with a total input-referred current noise of 48 pArms and a current consumption of 210 μA per channel.

This work presents the parasitic feed-through capacitance in a MEMS capacitive gyroscope with push-pull configuration. The push-pull configuration was adopted for driving the gyroscope resonator differentially to nullify the linear acceleration effect. The drive mode oscillator of the gyroscope was analyzed theoretically and experiments were carried out to quantize the parasitic feed-through level. It was found that the push-pull configuration worsen the signal to noise ratio by adding up the feed-through noise level at the difference amplifier. We proposed a novel feed-through cancellation scheme after the charge amplifier stage. The experimental results show that, signal to noise ratio (SNR) of 2 dB was achieved without feed-through cancellation. Furthermore, by exploiting the proposed technique, the signal to noise ratio was improved to 28 dB.

To solve the accuracy of measurement can't satisfy the requirements of the problem problem of the charge amplifier with very unstable working condition and much high interference, it is very necessary to design a new high accuracy and high accuracy pulse measuring instrument based on 51 single chip microcomputer. Established the pulse signal denoising MATLAB simulation model, using pulse waveform simulation of ideal artificial add noise to simulate the actual pulse wave. Through wavelet transform filter, used to confirm the practical effect of this method. It is used to determine the adopted ST188 photoelectric sensor to induct the pulse signal comparativing the disadvantage of piezoelectric sensor. Then the signal is filtered by STC89C52 microcontroller, and the pulse number is calculated quickly, accurately. The tester has been successful and it is proved that the whole test instrument has the advantages of strong anti-interference, high stability, accuracy, safety and comfort.

This paper presents a K-band power amplifier integrated circuit using Samsung 65 nm CMOS process. The power amplifier adopts two-stage configuration for high power gain. The input, output, and inter-stage transformers are integrated. By neutralizing gate-drain capacitance using cross-coupled capacitors, the power gain and stability were improved. Its chip size is 0.78 × 0.62 mm2. The implemented two-stage power amplifier showed a power gain of 19.6 dB, a saturated output power of 13.5 dBm, and an efficiency of 7.19 % with a supply voltage of 1.1 V at the frequency band of 24 GHz.

This paper presents a fully integrated low-power wearable respiration monitoring system using a pyroelectric transducer. Many chronic respiratory diseases such as asthma and apnea are leading causes of death worldwide which are even more critical for premature neonatal infants. Currently, the diagnosis of apnea requires the infants to go through overnight clinical sleep analysis, also known as polysomnography for 12 to 24-hour period. During this process numerous sensors are attached to the sensitive skin of the infants resulting in irritation and inconvenience. To overcome this problem a novel point-of-care respiration monitoring system has been proposed. At the front-end of the sensor a PVDF (Polyvinylidene Fluoride) based pyroelectric transducer is used which could be placed under the nasal cavity or inside a cannula of the subject. The charge generated by the transducer due to the nasal air flow is then converted to a proportional voltage signal by an operational transconductance amplifier (OTA) based charge amplifier. The subsequent signal processing blocks detect and process the signal coming out of the charge amplifier if it lies within the voltage range that corresponds to an apneic event. Once the signal is detected an alarm signal is generated indicating the occurrence of an apneic event. The light-weight design and smaller footprint of the transducer as well as the integrated devices make it suitable as a wearable sensor for non-invasive respiration monitoring. A prototype device with the integrated circuit fabricated using 0.5µm CMOS process is presented in the paper which can prevent many major disorders that can lead to neonatal mortality.

A low-noise head amplifier has been developed for the extra low energy antiproton ring beam trajectory, orbit, and intensity measurement system at CERN. This system is based on 24 double-electrode electrostatic beam position monitors installed around the ring. A head amplifier is placed close to each beam position monitor to amplify the electrode signals and generate a difference and a sum signal. These signals are sent to the digital acquisition system, about 50 m away from the ring, where they are digitized and further processed. The beam position can be measured by dividing the difference signal by the sum signal while the sum signal gives information relative to the beam intensity. The head amplifier consists of two discrete charge preamplifiers with junction field effect transistor (JFET) inputs, a sum and a difference stage, and two cable drivers. Special attention has been paid to the amplifier printed circuit board design to minimize the parasitic capacitances and inductances at the charge amplifier stages to meet the gain and noise requirements. The measurements carried out on the head amplifier showed a gain of 40.5 and 46.5 dB for the sum and difference outputs with a bandwidth from 200 Hz to 75 MHz and an input voltage noise density lower than $400~\text {pV}/\surd \text{Hz}$ . Twenty head amplifiers have been already installed in the ring and they have been used to detect the first beam signals during the first commissioning stage in November 2016.

This paper set up two structures model of switched-capacitor circuit based on second-order output settling, one type is charge transfer, the other is capacitance overturn. According to charge conservation when in charge storage and charge transfer process, the transfer function derived. By analyzing the time-domain solution in the form of output function, we find out the factors which influence on the rate of SC. In order to achieve the fastest settling time, the phase margin of open-loop amplifier is 63.4° in charge transfer by calculated, while in capacitance overturn is 76°.

This paper describes a capacitive touch-screen panel (TSP) readout IC that provides a reconfigurable SNR and frame rate with high noise immunity and touch sensitivity. The readout IC mitigates severe noise interference with a lock-in sensing architecture. In addition, a band-pass filtering effect by the TSP and charge amplifier further improves the noise immunity. A differential sensing scheme is employed to enhance the touch sensitivity and to reject a common-mode noise. A column-parallel incremental ΣΔ ADC is adopted to provide a high resolution and frame rate. Furthermore, a multiple sampling and averaging effect of the ADC enhances the noise immunity. The readout IC reconfigures its SNR and frame rate by adjusting the configurable resolution of the employed ADC. The test chip is fabricated in a 0.18 μm CMOS process and occupies a 2.2 mm 2 active area. The test chip achieves a 60 dB SNR and 200 Hz frame rate with a 12×8 TSP. The SNR can be adjusted from 40 dB to 67 dB, while the frame rate is then inversely scaled from 50 Hz to 6.4 kHz. The test chip supports a supply voltage range from 2.1 V to 3.3 V and consumes 6.26 mW from a 3.3 V supply.

The need of performing high resolution fast neutron spectroscopy in a very harsh environment like that of the Radial Neutron Camera (RNC) of ITER, requires to develop new detectors and methodologies. Diamond detectors have been proved to be excellent candidates but the electronics needs a substantial improvement. Because of the high radiation level and the temperatures expected near the detector positions in the RNC, the electronics must be placed several meters away. A novel Fast Charge Amplifier (FCA) was developed that, connected to a diamond detector using several tens of meters of low capacitance coaxial cable, is able to produce fast output signals suitable to be processed by digital electronics. These fast output signals allow to operate at high count rates avoiding pile-up problems. This novel amplifier connected to a digitizer is here tested in the neutron energy range from 5 to 20.5 MeV using the mono-energetic neutrons produced by the Van de Graaff (VdG) accelerator of the EC-JRC-IRMM and by the PTB cyclotron. From the measurements the experimental response functions of the diamond detector at different neutron energies were obtained. The shape of the response functions have been compared with that predicted with a routine which was implemented for the Monte Carlo code MCNPX with the scope to validate the calculations versus the experimental data. The goal is to develop a tool which allows to calculate the diamond detector response functions also in term of absolute efficiency. This methodology along with the ability to measure at high reaction rates and the insensitivity to radiation damage launches the system described in this paper as a promising method for neutron spectrometry in the RNC of ITER. © 2014 Elsevier B.V.

Digital piezoelectric constant testing system was designed in this paper, which was based on hydrostatic test method. The system is composed of hydrostatic device, charge amplifier circuit, peak holding circuit, A/D calibration circuit, data processing by DSP. Pressure-release value is obtained by digital pressure transmitter on the hydrostatic device. Combining with mean filtering and A/D calibration, DSP can sample accurate voltage signal. Considering the difference between the equivalent circuit of charge amplifier and its practical circuit, the calculated hydrostatic piezoelectric constant is in better agreement with the theoretical value. The experiment results show that the accuracy of testing system is less than 4%.

This paper presents a high unity gain bandwidth fully differential folded-cascode operational amplifier using gain-boosted technique. The amplifier is designed in TSMC 0.18μm 1P6M CMOS technology. The unity-gain bandwidth (GBW) and poles of the gain-boosting amplifiers were carefully designed to improve the stability. The implemented design provides a direct current (DC) gain of around 93 dB with a unity gain frequency of 1.8GHz. It exhibits a DC gain larger than 88dB when the output common-mode voltage between 0.6 V and 1.2V. the overall layout size is 96μm×120μm.

In this paper, we propose an energy-efficient 13-bit capacitive sensor interface circuit. The proposed design fully relies on successive approximation algorithm, which eliminates the need for oversampling and digital decimation filtering, and thus low-power consumption is achieved. The proposed architecture employs a charge amplifier stage to acheive parasitic insensitive operation and fine absolute resolution. Moreover, the output code is not affected by offset voltages or charge injection. The successive approximation algorithm is implemented in the capacitance-domain using a coarse-fine programmable capacitor array, which allows digitizing wide capacitance range in compact area. Analysis for the maximum achievable resolution due to mismatch is provided. The proposed design is insensitive to any reference voltage or current which translates to low temperature sensitivity. The operation of a prototype fabricated in a standard CMOS technology is experimentally verified using both on-chip and off-chip capacitive sensors. Compared to similar prior work, the fabricated prototype achieves and excellent energy efficiency of 34 pJ/step.

This paper presents a device for managing the inertial loads on photoreticles of lithography scanners. At high scan accelerations, the reticle inertial load can approach the clamp force limit. As a result, nanometer-level presliding slip can occur. Reticle slip is one limitation on increasing the throughput of the lithography scanners. In this paper, we present a reticle assist device which can eliminate reticle slip by compensating better than 95% of the inertial loads when tested in a bench-top tester. The reticle assist device consists of a coarse approach mechanism, for accommodating reticle load/unload, and a piezoelectric stack for fine actuation. The device utilizes a sensorless control system design. The control system uses a self-sensing contact detection method, which is inspired by self-sensing scanning probe microscopy, to find the reticle edge. It also uses a charge amplifier with a novel hybrid hysteresis compensation technique to linearly control the piezoelectric actuator extension, without the need for closed-loop position control. When tested with a replicated force profile with 60 N peak force and 6400 N/s force rate, the assist device compensated better than 95% of the inertial load.

A new single Miller capacitor for frequency compensation of three-stage amplifier is proposed in this paper. In this scheme, a differential stage in which its negative and positive inputs are connected to the output and input nodes of third stage with a cascade capacitor forms the compensation block of a conventional three-stage amplifier. Analysis shows that this configuration significantly improves the frequency domain performances of total circuit such as phase margin PM and gain-bandwidth product GBW with just a very small amount of compensation capacitor. A three-stage amplifier has been simulated with and without a differential feedback path in a 0.18µm complementary metal-oxide-semiconductor CMOS. The simulated amplifier with a 100pF capacitive load achieved more than 9MHz GBW and 83i¾? PM while the compensation is less than 0.2% of load capacitor. An amplifier based on conventional nested Miller compensation can just achieve less than 0.23MHz GBW with the same load, while using more than 100pF as compensation capacitor. So this method shows an improvement of a factor of 40 in GBW and reduction of a factor of 550 in the size of compensation capacitor. It is a suitable strategy for ON-CHIP compensation in comparison to other methods. Copyright © 2014 John Wiley & Sons, Ltd.

The present paper reports the details of the preliminary study towards the establishment of DC charge calibration facility at CSIR-NPL down to pico-coulomb ranges using charged capacitance source. The work involves the development of an automated electric charge generation and measurement setup using automation measurement program developed in LabVIEW programming environment. Charge measurements down to 100 pC have been performed with very good measurement accuracy and the expanded uncertainty has been evaluated as per ISO GUM document.

We have successfully demonstrated the fabrication of piezoelectric rubber films and their applications in heartbeat sensing and human energy harvesting. To realize the desired stretchability and electromechanical sensitivity, cellular polydimethylsiloxane (PDMS) structures with micrometer-sized voids are internally implanted with bipolar charges, which function as dipoles and respond promptly to diverse electromechanical stimuli. The resulting composite structures behave like rubber (with an elastic modulus about 300 kPa) and show strong piezoelectricity (with a piezoelectric coefficient d33 higher than 1500 pC/N). In the prototype demonstration, an autonomous heartbeat monitoring system utilizing stacked piezoelectric PDMS films is demonstrated. While integrated with a 12-μA h solid-state energy storage device and a 552-nW nano-power charge amplifier, the energy harvested from human body is stored and employed to monitor heartbeat. With a working area of 10 cm2 and a compressive load of 10 kg, it is estimated that a charge of 0.1 μC/cycle can be collected using a single-layered piezoelectric rubber film. Furthermore, multiple layers can be stacked and connected in parallel to magnify the charge output. As such, the demonstrated piezoelectric rubber films, which function as both stretchable energy harvesters and highly-sensitive impact sensors, possess a great potential for the realization of wearable and implantable human physiological monitoring systems.

An efficient three-stage amplifier with a new compensation method called single Miller capacitor feedforward compensation (SMFFC) which is suitable for large capacitive load applications are introduced in this paper. The overall layout area of the amplifier can be significantly reduced without influencing their stability by using a single Miller compensation capacitor in a three-stage amplifier. Pole-splitting and feedforward techniques are effectively combined in this compensation method to achieve a better performance.

It is shown theoretically and by experimentation that the ac stray immune capacitance meter based on the charge amplifier circuit can be modified to reduce the effects of the parasitic capacitance across the feedback capacitor. This is achieved by simply introducing a unity gain buffer amplifier within the circuit loop.

Due to the inductor-capacitor (LC) filter, a pulsewidth-modulation (PWM) current-source converter may experience LC resonance. The resonance can be excited by system harmonics either from the PWM process or from the grid voltage distortions and hence results in the line current distorted. In this paper, feedback controls using different variables in the LC filter are first investigated and comprehensively analyzed. It is shown that the inductor-voltage feedback or the capacitor-voltage feedback can damp the current oscillations by increasing the damping ratio, while the inductor-current feedback or the capacitor-current feedback is able to suppress low-order harmonics by raising the resonance frequency. On this basis, a group of combined variable feedback control methods is presented by combining the feedbacks of the inductor/capacitor current and the inductor/capacitor voltage. Thus, not only the current oscillations can be damped, but also the low-order harmonics can be suppressed. Therefore, the line current waveform is improved, and the system performance can be flexibly optimized. A practical design method for feedback gains is also presented in this paper. Finally, the simulation and experimental results verify the feasibility and validity of the proposition.

A surface micromachined microphone is presented with 230 kHz bandwidth. The structure uses a 2.25 μm thick, 315 μm radius polysilicon diaphragm suspended above an 11 μm gap to form a variable parallel-plate capacitance. The back cavity of the microphone consists of the 11 μm thick air volume immediately behind the moving diaphragm and also an extended lateral cavity with a radius of 504 μm. The dynamic frequency response of the sensor in response to electrostatic signals is presented using laser Doppler vibrometry and indicates a system compliance of 0.4 nm/Pa in the flat-band of the response. The sensor is configured for acoustic signal detection using a charge amplifier, and signal-to-noise ratio measurements and simulations are presented. A resolution of 0.80 mPa/√Hz (32 dB sound pressure level in a 1 Hz bin) is achieved in the flat-band portion of the response extending from 10 kHz to 230 kHz. The proposed sensor design is motivated by defense and intelligence gathering applications that require broadband, airborne signal detection.

Soft piezoelectric actuators are extensively used in micro- and nanopositioning applications. Traditional sensorless position control approaches use a hysteresis mapping between voltage and position in a voltage feedforward control scheme in order to compensate for hysteresis errors. However, several factors such as frequency, temperature, and aging influence this mapping. Recently, charge control for positioning is also attracting interest among researchers due to the linear relationship between position and charge. However, a sophisticated hardware design is required to minimize charge drift. In this study, a new sensorless position control technique is proposed which requires neither an accurate inverse mapping nor a sophisticated charge amplifier in order to compensate for hysteresis. A constitutive relationship is employed to infer position from charge measurement through current integration. To eliminate drift from the charge-based measurement, an observer is presented in this study which uses a second self-sensing position estimate that is based on the variation of effective piezoelectric capacitance with stroke. The proposed observer is tested as a position feedback sensor inside a simple integrating control loop and applied to step profiles of variable stroke and sinusoidal profiles of constant and mixed frequencies. The responses are compared with a laser interferometer and the maximum observer error between the laser and the observer is 0.89 μm ( 3% of the maximum stroke) over a frequency range of 10 to 100 Hz.

This paper proposes an active low-frequency ripple control device (ALFRCD) based on virtual capacitor concept for building-integrated photovoltaic (BIPV) systems. With this method, the power quality of the BIPV system can be enhanced, and the lifetime and reliability are superior by reducing electrolytic capacitors. The low-frequency ripple current caused by the single-phase inverter can be compensated promptly by introducing a current integrator instead of unit feedback in the control strategy of the ALFRCD. With this current integrator, the device is unable to output dc current, which is similar to the function of a capacitor. Compared with the conventional method with high-pass filter, the presented method can achieve better compensation efficiency at most of the low frequencies and the response speed is superior as well. In addition, only one more integrator is needed in the control loop, which indicates the conciseness of the method. The performance is analyzed and the design algorithm is introduced in detail. Simulations and experimental results verified the proposed method's reliability and superiority in comparison with the method with high-pass filter and a proportional-integral controller.

The IPMC has perceived performance, so it can be used for making micro-force sensor. But its sensing signal is very weak, a greater influence on perception from the environmental noise signals. In the paper, we design a micro-force sensor system based on IPMC. The current signal conversion of analog circuit, voltage signal amplification, signal processing and other key parts are introduced, meanwhile, the calibration to micro-force sensor is completed.

In this paper, a method is proposed for minimizing stability factor and removing the negative feedback from Self Bias Configuration of an Amplifier. Stability is an important concern in the designing of Amplifier. For stabilization of an Amplifier different biasing techniques are used. Among all biasing techniques Self Bias technique is best but the major drawback is the introduction of negative feedback by Emitter resistance Re. Due to the introduction of negative feedback the gain of an amplifier decreases. An ideal Ammeter has infinite internal resistance so to remove the negative feedback an ideal Ammeter is used instead of Emitter resistanceRe. With the application of proposed method the Stability factor is minimized and coming out to be equal to Unity and the problem of negative feedback is also removed. In this paper the analysis of proposed Self Bias Circuit is done with the help of Thevenin Theorem.

The vibration is severe for a hydraulic turbine runner chamber of a large bulb hydraulic generator set. A measurement and analysis system is composed of an acceleration transducer, a charge amplifier, and a dynamic data collecting & analyzing system. It is used to test the frequency spectrum, which provide a basis for the optimization design based on the modal analysis, so that its natural frequencies can stagger these frequencies of vibration sources, the resonance does not occur and the vibration is reduced.

A lock-in amplifier was proposed for capacitive sensor applications. This amplifier was based on a general-purpose microcontrollerand had only a charge amplifier as analog circuits. All the ot her functions of lock-in amplifie r except for the charge amplifier were imple-mented with firmware and the internal resources of the microcontroller. A rectangular signal, generated by the microcontroller, was usedin a sensor-driving signal instead of a conventional sinusoidal signal. This makes it possible that the phase comparison circui t in the lock-in amplifier is made with analog-to-digital converter, a timer and an interrupt controller. Using the oversampling method and the rect-angular driving signal, we can make it easy to implement the peak detection function with software and sample the peak-to-peak signalat charge amplifier output. A charge amplifier was proposed to cancel out the base capacitance existing in capacitive sensors structurally.The experimental results show that the lock-in amplifier operating in the supply voltage of 3.0 V cancels out the base capacitance andhas good linearity.

An operational amplifier is one of the most commonly used components in analog and digital circuit designs. Low voltage and low power operational amplifier design has become an increasingly interesting subject as many applications switch to portable battery powered operations. The need for design techniques to allow amplifiers to maintain an acceptable level of performance when the supply voltages are decreased is immense. One of the most important features in low voltage amplifier designs is ensuring that the amplifier maintains constant behavior in the presence of rail-to-rail input common mode variations while providing a rail-to-rail output to maximize signal-to-noise ratio. As the supply voltage to a standard CMOS op-amp is reduced, the input common mode range and the output swing get reduced drastically. Special circuits have to be used to raise them up to rail-to-rail supply voltage. In this work we propose a design of a low-voltage CMOS rail-to-rail folded cascode operational amplifier to be realized in a standard 130 nm CMOS technology with 1.2V supply voltage and consumes power less than 400uW. A two stage miller compensated folded cascode op-amp has a UGB >10MHz and achieves a gain >80dB over almost full range of the common mode input voltage.

Charge amplifier is the key component in the pre-processing circuit of the sensors. With the development of the sensor technology, the charge amplifier on the market has not been able to meet the requirement of the actual measurement. In this paper, a LF356-based charge amplifier is suitable for the conversion circuit of the polyvinylidene fluoride (PVDF) piezoelectric sensor, duing to its small volume, low power consumption and strong anti-interference. The fesibility and reliability of the charge amplifier are verified by simulating the circuit with Multisim10 and testing the hardware circuit. This charge amplifier achieves a volume of 19.32 cm3 and a bandwidth between 20kHz and 150kHz at a power consumption of 1 mW. Performance of this charge amplifier is investigated when it is connected to a standrad signal source, achieving a gain of 10 times.