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The ZnO film as the material, the charge amplifier and the accelerometer in one set, to record and display the measurement data directly, simplifying the testing system to improve the test accuracy and reliability. Charge amplifier circuit is designed to be simple, easy to debug, high integration, low cost, favorable ZnO thin films driven by the widespread use of the accelerometer.

The High-Speed Image Pre-Processor with Oversampling (HIPPO) is a prototype image sensor readout integrated circuit designed for both high performance and enhanced flexibility. HIPPO's initial target application is the instrumentation of bufferless, column-parallel, soft x-ray Charge-Coupled Device (CCD) image sensors operating at column rates up to 10 MHz, enabling 10,000 frames-per-second (fps) video rates. HIPPO's architecture is flexible and allows design tradeoffs between speed, accuracy, and area. This architectural flexibility will enable the fast development of related image sensor and particle detector readout ICs based on HIPPO technology. HIPPO contains 16 channels, each comprising a charge amplifier, a dual-slope correlated double sampler, a sample-and-hold, a multiplexed 12b, 80 MS/s pipelined ADC (one ADC for every 4 channels), and a 480 Mb/s output serializer. HIPPO achieves 35 e-read noise at 10,000 fps for a 1 Mpixel sensor, improving to 24 e-at 5000 fps. HIPPO's charge-domain input obviates the source follower amplifier used in most CCDs and enables the implementation of a fully column-parallel CCD architecture. HIPPO was specifically designed to be flexible in both the sequencing of its operations and in its ability to accommodate input rates potentially varying over an order of magnitude.

We start with an analysis of the configurations commonly adopted to implement linear shapers. We show that, once the ENC from the charge amplifier is defined, the dynamic range of the system is set by the voltage swing and the value of the capacitance realizing the poles. The configuration used to realize the poles has also an impact, and those configurations based on passive components in feedback are expected to offer a higher dynamic range than the ones that use both active and passive components, like scaling mirrors. Finally, we introduce the concept of delayed dissipative feedback (DDF), which consists of delaying the resistive feedbacks from the furthest available nodes along the shaping chain. We will show that, in order to implement semi-Gaussian shapers, a small capacitor in positive feedback is required. The DDF technique can overcome some of the limitations of the more classical configurations. For example, in a third order shaper a factor of two higher dynamic range can be obtained or, at equal dynamic range, about 25% of the capacitance is needed (i.e. about 30% of the area in practical cases).

Cardiac contractions bend the implanted cardiac lead body, and extend and compress the lead conductors, their insulation, and the inserted stylet. Magnitude of lead deflection depends on cardiac muscle contraction forces. The purpose of this study was to measure the charge generated due to triboelectric effect between one of the lead conductors and the inserted stylet. The charge was measured by a differential charge amplifier being connected to an isolation amplifier and power supply. Sensor signal, ECG, and intracardiac electrograms were acquired. Three models of custom-designed leads were implanted in eight sheep. Measurements were done in 18 patients undergoing pacemaker implantation and replacement procedures. Atrial and ventricular tensiometric signals were recorded in dual chamber and in single-lead ventricular diastolic dysfunction patients. Recordings in sinus rhythm at various atrioventricular intervals and in supraventricular tachycardia were done. On average, charge variation between 1 and 600 pC was measured. Tensiometric stylet could be feasible hemodynamic sensor for myocardial contraction detection. Its main advantage is that it is easily exchangeable and universal for all leads.

A cheap signal processing circuit was designed to replace expensive special charge amplifier which was used for shock wave pressure sensor. We used conventional electrical components to design the charge amplifying circuit and the filter circuit. A fine image of shock pressure wave was got using this signal processing circuit in a real fire experiment.

This letter describes a multiply-by-two amplifier inherently insensitive to capacitor mismatch with an enhanced feedback factor of approximately unity. The proposed flipped-around structure, which operates in a single clock cycle, is based on the series association of two charged capacitors to achieve an accurate gain of two. Due to the series association of the capacitors, a nearly unity feedback factor is achieved, greatly enhancing the energy efficiency of the circuit. Simulations, in a standard 0.13 μm 1.2 V CMOS technology, also show a fourfold linearity improvement over the conventional structure.

Based on laboratory experimental results obtained with an axial threshing test-rig with tangential feeding, cumulative distribution functions of separated grain in axial and radial directions of threshing rotor were built. Based on the analysis of the relationship between grain separation loss and grain separation flux in an area under the concave, an indirect grain separation loss monitoring method is presented in this paper. Piezo-electric polyvinylidene fluoride (PVDF) film was selected as sensitive material to design a grain flux sensor. While grain and material-other-than-grain (MOG) separated in the monitoring area impact on piezo-electric PVDF films, different electric charges are generated. After signal progressing with a charge amplifier, frequency discrimination and wave shaping, the number of grain can be counted by a microcontroller (MCU) and the grain separation loss of combine harvester can be measured in real-time. Field test results indicated that the measurement errors of grain separation loss recorded by the monitoring system relative to the loss checked manually were less than 12%.

This brief presents a rail-to-rail input-output precision operational amplifier with integrated laser-trimmable polysilicon resistors for reducing the input offset voltage. The amplifier is fabricated in a standard Taiwan Semiconductor Manufacturing Company 0.18-μm complementary-metal-oxide-semiconductor process technology. The resistors' trimming sequence allows for minimizing the offset voltage over the complete input common mode voltage range (ICMR) extending from the ground to the supply. Experimental results are presented to demonstrate the steps involved in offset-voltage trimming. The prototype amplifier drives a 400-pF capacitive load and operates from a 3.3-V supply. The amplifier is unity-gain stable with a phase margin of 58° and has an open-loop direct-current gain greater than 130 dB with a unity-gain bandwidth of 0.5 MHz. Experimental results show that an untrimmed input offset voltage ranging from +0.1 to +0.5 mV over the ICMR was reduced to -30 to + 30 μV.

The output of the linear feedback amplifier is modelled as the superposition of a series of succeeding feedback components. The loop circuit is interpreted as a distributed delaying circuit that spreads an instantaneously applied impulse signal into many infinitesimal components of various delay times. This interpretation is used to explain that the instantaneous feedback component is infinitesimal regardless of how large the loop gain is. Since the instantaneous loop gain between succeeding feedback components is infinitesimal, convergence of the series can be achieved. The relationship between the input and output of the overall system is then derived. We hope that our point of view can provide more insight into the operating mechanism of the feedback circuit and serve as a bridge between introductory textbooks and Nyquist's theory.

We propose that electrochemical cells based on bacterioRhodopsin (bR), a photosensitive protein, generate electric charges under illuminated light and that a suitable signal detection apparatus for this cell type is a charge amplifier. By using charge amplifiers, we observed bR-photocell electric charges that were proportional to the intensity of incident light, which ranged from 0 to 8mW/cm2. Then, the 4 × 4 micro-patterned bR photosensor array was connected to charge amplifiers to form an image sensor system. Static and moving images were detected with the constructed image sensor system.

As the initial step to realize a reliable measurement of the secondary electron yield of insulating materials using charge amplification method proposed by K. Goto [1-3], a pair of the charge amplifiers to measure a small amount of the electron charge of less than ~ 1pC have been developed. These amplifiers showed linear input/output characteristics within the range of the input charge of ~0.3 to ~5 pC. The total secondary electron yield σ(E) of soot was measured by employing these charge amplifiers, and compared with that measured by the conventional current-mode method. The result showed that the charge amplification method enables the secondary electron yield to be measured using the primary electron charge of only ~1 pC. The primary electron charge can be further reduced to at least ~ 0.1 pC by improving the charge amplifier.

We have been developing low power cryogenic readout electronics for space borne large format far-infrared image sensors. As the circuit elements, a fully-depleted-silicon-on-insulator (FD-SOI) CMOS process was adopted because they keep good static performance even at 4.2K where where various anomalous behaviors are seen for other types of CMOS transistors. We have designed and fabricated several test circuits with the FD-SOI CMOS process and confirmed that an operational amplifier successfully works with an open loop gain over 1000 and with a power consumption around 1.3µW as designed, and the basic digital circuits worked well. These results prove that the FD-SOI CMOS process is a promising candidate of the ideal cryogenic readout electronics for far-infrared astronomical focal plane array sensors.

Proposed amplifier with capacitance inputs and internal resistor feedback to adjust gain factor. The obtained characteristics (SFDR > 100 dB SNR > 120 dB) provide 16-bit accuracy, necessary for creation of a pipelined ADC similar capacity.

The output characteristics of the basic current feedback operational amplifier (CFOA) in the linear region, on open-loop, would not appear to have been treated in the literature. This is possibly because it is not straightforward to determine, the problem being that the output saturates without the closed-loop connection. This paper considers a theoretical discussion that explains the results of simulation.

A new testing method for hydrostatic piezoelectric constant, dh , was studied in this paper. This testing system consists of five parts, which are hydrostatic simulator, signal acquisition and processing circuits, data acquisition, serial communication interact circuit, data processing and display. Researched the method of signal acquisition for hydrostatic piezoelectric charge, designed the charge amplifier circuit, signal processing circuit as well as the data acquisition and serial communication interact circuit with microcomputer, programmed for the date acquisition and processing system software. The hydrostatic piezoelectric constant, dh , of piezoelectric ceramic samples were tested. The experimental results showed that this new testing method is available. The new testing system is characteristic of manipulation simply and low cost.

This paper proposes a differential structure sensor for detecting Ringer`s solution exhaustion, in which three C-type electrodes of 10 mm width are disposed on a ringer hose at a distance of 5 mm each other in the direction of Ringer`s solution flow. In the center of middle electrode, two capacitances are formed at the proposed sensor. When ringer hose is filled with Ringer`s solution, there is no difference between two capacitances. But capacitance difference exist under the Ringer`s solution shortage, because the shortage causes the hose filled with air from the top position electrode. The capacitance difference got to maximum 1.81 pF, when air was filled between top and middle electrode and the last of hose was filled with 10 % dextrose injection Ringer`s solution. The capacitance difference varied with hose-wraparound coverage of electrodes as well as the width of them. For hose-wraparound electrode coverage of 90 % and 70 %, the maximum capacitance difference was 1.81 pF and 1.56 pF, respectively. A differential charge amplifier converted the capacitance difference to electric signal, and minimized electrodes` adhering problem and external noise coupling problem.

Charge amplifier calibration at low frequencies is a time-consuming service. This paper presents a method to speed up the process by measuring decades of frequencies in a single run. Based on the calibration results gained, a filter design process is introduced that facilitates a multi-rate approach to digital IIR filters in order to circumvent the complications arising from high-pass filtering with low corner frequency at high sampling rates.

A new digital average current-mode control technique is proposed for dc-dc converters operation in discontinuous conduction mode. In contrast to the regulation of inductor current, this paper focuses on how the suitable charge current is feed to capacitor and load resistor directly. Using the principle of capacitor charge balance, the charge current reference in next switching cycle is predicted in order to drive the output voltage back to its nominal value quickly during transient conditions. The actual average charge current is estimated from a simplified algorithm, which can also be used to calculate the required duty ratio according to the charge current reference. This control technique features good dynamic performance and it is compliant with the performance constraints of digital integrated processor. The effectiveness of the proposed solution has been proved by the simulation and experimental results.

In this paper, a highly area-efficient controller for capacitive touch screen panels (TSPs) is proposed. The proposed controller uses a 10-bit successive approximation register analog-to-digital converter (SAR ADC) with an adder to compensate for the capacitance variation in the TSP and for the offset voltage variation in the charge amplifier of the sensing circuit. By using the proposed compensation method, the area of the controller can be reduced by 90.3% of the area of the conventional controllers. The measurement results showed that the signal-to-noise ratio (SNR) of the controller increases from 12.5 to 21.3 dB after compensation. Also, its spatial jitter decreases from ±1.5 to ±0.46 mm, which is 7% of the sensor pitch of 8 mm.

A pulsed bias voltage shutdown circuit to suppress the polarization effect in a CdTe radiation detector equipped with a matrix readout system was investigated. The matrix readout system is suitable for radiation detection systems that have many pixels and that are used at a relatively low counting rate, such as single photon emission computed tomography (SPECT). CdTe detectors have a time-dependent polarization effect that must be suppressed. One method to suppress this effect is pulsed bias voltage shutdown. However, on the bias voltage supply side of the matrix readout system, the speed of the voltage change depends on a time constant consisting of a bias resistor and a coupling capacitor. Therefore, the voltage cannot be changed within the time constant for the matrix readout system. To overcome this limitation, three circuits have been added: a clamp circuit to the noise filter resistor of the bias voltage supply, a clamp circuit to the bias resistor, and protection circuits at the charge amplifier inputs. These circuits make it possible to change the bias voltage faster than the time constant of the bias resistor and the coupling capacitor. Although a noise signal is observed after the bias voltage has recovered, the noise decays below 20 keV about 30 ms after the bias voltage recovery. Our results demonstrated that the proposed pulsed bias voltage shutdown method is very efficient to suppress the polarization effect within 100 ms for the CdTe detector with the matrix readout system.

An improved modulated carrier control (MCC) method is proposed to offer high power factor (PF) and low total harmonic distortion (THD) at a wide input voltage range and load variation. The conventional MCC method not only requires a multiplier and divider, but also is hard to be implemented with a micro controller unit without a high frequency oscillator. To overcome the problem and maintain the advantages of the conventional MCC method, the proposed MCC method adopts a current integrator, an output voltage amplifier, a zero-current duration (ZCD) demodulator of the boost inductor, and a carrier generator. Thus, it can remove a multiplier and well, as it allows for being operable with a general micro control unit. This paper presents an operation principle of the proposed control method. To verify the proposed control method, experimental results with 400 W PFC boost converter is demonstrated.

This paper presents the design and testing of a one-axis piezoelectric accelerometer made from cellulose paper and piezoelectric zinc oxide nanowires (ZnO NWs) hydrothermally grown on paper. The accelerometer adopts a cantilever-based configuration with two parallel cantilever beams attached with a paper proof mass. A piece of U-shaped, ZnO-NW-coated paper is attached on top of the parallel beams, serving as the strain sensing element for acceleration measurement. The electric charges produced from the ZnO-NW-coated paper are converted into a voltage output using a custom-made charge amplifier circuit. The device fabrication only involves cutting of paper and hydrothermal growth of ZnO NWs, and does not require the access to expensive and sophisticated equipment. The performance of the devices with different weight growth percentages of the ZnO NWs was characterized.

Electrostatic capacitance measurement method in a fine hose was proposed, in which two ring-type electrodes were disposed on the hose in the direction of fluid flow instead of the conventional face-to-face electrodes. With the proposed electrode structure, we realized a Ringer`s solution exhaustion detector for an IV(invasive vein) injection set. On a 4 mm-diameter hose of IV set, we disposed two ring-type electrodes of 10 mm width at a distance of 5 mm each other and obtained 0.72 pF and 2.51 pF for air and 10 % dextrose Ringer`s solution in the hose, respectively. The capacitance between the two electrodes varied with the hose-wraparound coverage of electrode as well as the width of electrode and the distance between the electrodes. For hose-wraparound electrode coverage of 75 %, the capacitance varied from 0.62 pF to 1.98 pF with the Ringer`s solution level between the two electrodes. A charge amplifier converted the capacitance. variation into electric signal and a comparator was used to detect whether Ringer`s solution was exhausted or not. The result was delivered to a host using a RF transmitter with 320 MHz carrier frequency.

Storage systems based on scanning probe microscopy incorporate an array of thermopiezoelectric cantilevers that require charge amplifiers with a wide frequency response but low power consumption. We use an improved frequency compensation method to enhance the in-band frequency response without requiring any additional power. Measurements show that the prototype chip draws the same 68 A at 1.8 V as an unmodified design but has a closed-loop frequency response that is ten times greater. The chip was fabricated in a 0.18-m standard CMOS process, and the charge amplifier core occupies 0.042 mm2.

A low power digital operational transconductance amplifier (OTA) was developed for low voltage switched capacitor applications. The OTA has a high slew rate (SR) and a large open loop gain with a differential pseudo-two-stage Class-AB structure. A fully compensated depletion mode capacitor is used in the switched capacitor common mode feedback block instead of a metal-insulator-metal (MIM) capacitor to reduce the fabrication cost. Simulations show that with a 1.0-V supply voltage and a 34-pF load at each output terminal, this digital differential pseudo-two-stage Class-AB OTA realized in 0.13-μm technology achieves a 63.5-dB DC gain and a 0.83-V output swing. The slew rate is ±16.29 V/μs and the total power dissipation is only 82 μW.

An fF-level capacitive sensor, intended for pL liquid measurements, has been fabricated with MEMS technology and successfully characterized. The sensor measures liquid level variations in a microfluidic channel. The sensor’s capacitance varies from 1.5 fF (channel empty) to 12.8fF (channel filled with 63 pL of water). To reliably detect such small capacitance changes, a low noise measurement system, based on a lock-in amplifier, was implemented. The measured sensitivity of the system is 14.1 mV/fF, and the capacitance detection limit is 0.057 aF/Hz 1/2 , which corresponds to a volumetric resolution of about 0.22 fL/Hz 1/2 .

Generation of extensional waves in a linearly elastic bar by means of a pair of attached piezoelectric actuators driven by a power amplifier with output current constraints is studied theoretically and experimentally. In addition to its current constraints, the amplifier is characterized by its DC voltage gain and 3 dB cut-off frequency. On the basis of 1D wave propagation, time-domain relations are established for the nonlinear dependence of the output voltage and current of the amplifier, and of the strain associated with the waves generated, on the input voltage. It is found that the amplifier model used allows prediction of the main features of this dependence. Nonlinear operation due to constrained output current may occur even at a low input voltage if the rate of change of this voltage is excessive. Consideration of this phenomenon is important in, e.g., control applications.

This paper presents a new arrangement for the indicating measurement system utilized in the study of internal combustion engines. In this experimental configuration, the current polarized by a piezoelectric pressure transducer is converted into an analog signal proportional to the cylinder pressure variation rate, which constitutes the primary information for combustion heat release analysis. The proposed technique reduces the uncertainty in the pressure derivative data, providing more accurate heat release results than those obtained with the traditional transducer signal conditioning procedure, which requires the numerical derivation of in-cylinder pressure data supplied by a charge amplifier.

We have prototyped a switched capacitor DC-DC converter aimed at powering low voltage integrated circuits in particle physics instrumentation. The ideal output current is 4 times the input current. The prototype was built using a CMOS integrated circuit containing all switches and switch driver circuitry, with external capacitors and clocks. We present measurements of performance with and without irradiation.

This paper describes ramp rate control of a photovoltaic (PV) generator with an electric double-layer capacitor. The capacitor absorbs rapid fluctuations of PV generation, and allows the generator to change its output at a limited ramp rate. The output is mainly determined by a moving average of the PV generation, but the capacitor voltage is also counted to keep the voltage at a specified value, and accordingly, to make the capacitor small. An expression for the capacitor size is derived. The feedback gain of the capacitor voltage is also examined to maintain enough energy storage in the capacitor. Some experiments are executed to demonstrate and validate the proposed method.

We present a prototype, modular, autonomous fluidic sensor system that will be capable of long-term in the field use. Modularity extends from the ability of the system to support different sensing modes (gas or liquid), and autonomy extends from it being self-contained and operating independently. We demonstrate the first use of a custom CMOS integrated circuit that has a photodiode and charge amplifier for sensing, and combine this with a microcontroller to allow for autonomous operation in a very small package. The sensor portion can respond to color change in a liquid or intensity change from a luminescent chemical sensor. Ultimately, multiple sensors can be used at once to determine the concentration of pollutants.

This paper presents a capacitive-sensor interface with high accuracy and excellent stability. The range of the measured capacitance is up to 1 pF. The implemented circuit tolerates cable capacitances of up to 1 nF. Depending on the operation mode, the conversion time varies between 39 and 100 mus. The measurement principle permits a mode with compensation of small sensor leakage currents. The reference units are frequency, resistance, and resistance ratios, which provide high initial accuracy and a long-term stability. The measured temperature coefficient of the capacitance converter is about 2 ppm/K. A special multislope analog-to-digital conversion (ADC) is used, which, to increase the resolution, transfers itself at the beginning and at the end of the conversion process into an oversampling conversion. Based on the band-pass filtering function of the implemented ADC technique and the low-noise input stage used, a dynamic range of better than 14 b has been achieved for a cable capacitance that is less than 400 pF.

Piezoelectric sensor (PZT) based structural health monitoring (SHM) methods can efficiently estimate the health condition of aircraft structures. To monitor large-scale structures, dense PZT arrays are usually needed. How to scan different PZT actuator–sensor channels in the PZT array to achieve a real time and stable SHM task is an important issue in the application of these methods. In this paper, an integrated multi-channel PZT array scanning system (ISS) is developed for the purpose of SHM. A type of gain programmable charge amplifier and a low crosstalk scanning module are discussed. An integrated software system which is based on the LabVIEW software platform is developed to manage the hardware, and perform signal processing and damage estimation. To validate the functions of this system, an evaluation is performed on a carbon fiber composite wing box of an unmanned aerial vehicle (UAV). The application results show the promising performance of this system.

The paper covers a pure analog amplifier design favorable to drive capacitive solid state actuators such as piezoelectric actuators. The research in this field is prompted by the introduction of a new piezoelectric motor (piezoelectric actuator drive – PAD) which employs piezoelectric multilayer actuators, offering mechanical output power of up to 20 W. Due to their static and continuous operation, the actuators of the motor need to be supplied by high-quality, low-frequency, high-voltage, sinusoidal signals. The described circuit is an efficiency-improved class-B amplifier capable of recovering up to 50% of the charge stored in the actuator. The paper begins with a short overview of different amplifier types and their trade-off between signal quality, efficiency and circuit complexity. Starting with a description of the sources of power-loss in a basic class-B amplifier which drives a capacitive actuator, a hybrid design, combining the analog with a switched-mode amplifier, is discussed. The efficiency-improved class-B amplifier is then derived from the hybrid design. Finally, the amplifier is tested in an experiment together with the PAD.

A new high-speed charge transfer sense amplifier scheme is proposed for 0.5 V DRAM array applications. The combination of both the cross-coupled structure and the boosting capacitance used in the proposed sense amplifier leads to a maximum voltage difference between sense nodes. Based on post-layout simulations, the charge transfer speed and the voltage difference after charge transfer are improved 40.7% and 59.29%, respectively, over the prior art circuits. The power-delay product is then enhanced 38.26%. Besides, both high voltage pre-charge levels and high voltage control signals are not required in this proposed circuit as compared with prior arts.

A rail-to-rail amplifier with an offset cancellation, which is suitable for high color depth and high-resolution liquid crystal display (LCD) drivers, is proposed. The amplifier incorporates dual complementary differential pairs, which are classified as main and auxiliary transconductance amplifiers, to obtain a full input voltage swing and an offset canceling capability. Both offset voltage and injection-induced error, due to the device mismatch and charge injection, respectively, are greatly reduced. The offset cancellation and charge conservation, which is used to reduce the dynamic power consumption, are operated during the same time slot so that the driving period does not need to increase. An experimental prototype amplifier is implemented with 0.35-mum CMOS technology. The circuit draws 7.5 muA static current and exhibits the settling time of 3 mus, for a voltage swing of 5 V under a 3.4 kOmega resistance, and a 140 pF capacitance load with a power supply of 5 V. The offset voltage of the amplifier with offset cancellation is 0.48 mV.

We propose a dynamic range extension method for CMOS imagers with an in-pixel lateral overflow structure, in which one of active and passive readout schemes is selected at each pixel on the basis of the illumination. For a high illumination, the charges stored in both photodiode and area-effective MOS capacitor as an overflow capacitor in a pixel are read with high linearity by a charge amplifier at each column to extend the range of the readable voltage. The column circuit area is suppressed and row-wise pixels are accessed by sharing the pixel control signals and the column amplifier between two readout modes. We also describe an image reproduction scheme that makes use of electric calibration from a pixel-wise mixed-mode image. The signal-to-noise ratio of the scheme is discussed. Preliminary experiments with a 128 x96-pixel prototype imager fabricated in 0.35μm CMOS technology showed an extension of the dynamic range of 18.5 dB (72.8 dB in total) and offline wide-dynamic-range image reproduction. Optimizing of the capacitances in the pixels and the column amplifier and reducing the amount of noise in the column amplifiers will provide a total dynamic range of around 120dB.

A high-precision predictive switched-capacitor (SC) amplifier stage is described. It has a subsidiary signal path to desensitize op-amp imperfections such as low gain. In this paper, the effect of common-mode input voltage to the predictive SC amplifier is analyzed. Simulations using SPICE parameters of a 0.18 μm CMOS process indicate that small gain error and low harmonic distortion can be obtained even in the presence of common-mode input voltage of 200mV and that the circuit has immunity to the common-mode input voltage.

The necessity of the converters compactness in many applications imposes the reduction of their different components size when it is possible. In this paper, a control method allowing the use of a small size dc-link capacitor for the cascade of voltage controlled-rectifier/inverter-motor drive system is proposed. This is achieved by adding the power balance equation in the system’s model and the application of an exact input/output feedback linearization technique in a way that the rectifier controller compensates any sudden change in the inverter load, which is here an induction motor. Since the exact input/output feedback linearization technique is sensitive to the uncertainties over system parameters, a robust control strategy based on sliding mode controller is proposed. By this approach, the dc-link voltage becomes almost insensitive to the load variations. As a result, the level of the dc-link voltage could be stabilized with a small size dc-link capacitor. Without any considerations of the RMS current stress on this dc-link capacitor, a calculation method of a minimum value of this capacitor based on its storage energy is proposed. All the investigations are shown by computer simulations and the performance of controlled system is verified by experimentation results.

This paper proposes a circuit to linearize the signal current and improve the distortion characteristics at the input of a current-mode circuit. Input voltage-to-current (V/I) conversion is carried out by a resistor that connects the signal source and the current input terminal of the current-mode circuit. The signal current flowing into the current-mode circuit through this resistor is distorted because of the signal-dependent voltage change at the current input terminal, and it is linearized by injecting a current that is proportional to the signal-dependent voltage change at the current input terminal, into the same current input terminal of the current-mode circuit. A current-mode sample-and-hold amplifier (SHA) that adopts the proposed scheme was fabricated and a 0.35-mum CMOS process was used to verify the effectiveness of the scheme. It operated from a 2-V supply voltage in the analog part and a 2.5 V in the digital part with a 100-MHz clock and realized a 77- and a 86-dB spurious-free dynamic range values for 0 and -10 dB of full-scale signal current level (plusmn100 muA), respectively, of the 1-MHz signal input. More than a 13-bit equivalent SFDR for -14 to -4 dB of full-scale input was obtained, proving the effectiveness of the proposed scheme at realizing distortionless signal current processing.

A micromachined electrometer, based on the concept of a variable capacitor, has been designed, modeled, fabricated, and tested. The device presented in this paper functions as a modulated variable capacitor, wherein a dc charge to be measured is up-modulated and converted to an ac voltage output, thus improving the signal-to-noise ratio. The device was fabricated in a commercial standard SOI micromachining process without the need for any additional processing steps. The electrometer was tested in both air and vacuum at room temperature. In air, it has a charge-to-voltage conversion gain of 2.06 nV/e, and a measured charge noise floor of 52.4 e/rtHz. To reduce the effects of input leakage current, an electrically isolated capacitor has been introduced between the variable capacitor and input to sensor electronics. Methods to improve the sensitivity and resolution are suggested while the long-term stability of these sensors is modeled and discussed.

In this paper, an all-analog pixel architecture for the readout of X-ray pixel detectors with multiple energy discrimination is proposed. The circuit comprises a self-triggered reset charge amplifier and three distinct channels devoted to the detection on a specific energy band. Each channel is composed of an autocalibrated comparator, an energy window identification logic, and an analog counter with an adjustable dynamic range. A test prototype has been implemented with a standard complementary metal-oxide-semiconductor 0.35-mum technology. The pixel circuitry dissipates 15 muW at 3.3 V, has a noise equivalent charge of 82 erms - at 200 fF, and allows, on each of the three channels, a dynamic range that exceeds 12 bits. The designed pixel is a square with a 109-mum pitch.

This paper presents a precision current sensor featuring a high voltage, high gain (~ 140 dB), and low input offset ( < 1 mV) current sense amplifier. This amplifier does not require offset trimming even for low offset applications. It is a single stage amplifier that has a common gate pMOS differential input pair, which makes it inherently stable. This amplifier topology allows for a wide input common-mode range, thus increasing the versatility of current sensing circuit.

We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated cadmium-zinc-telluride (CZT) sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplifier's voltage output; the second uses the threshold crossing of a fast-shaped signal; and the third measures the peak amplitude and timing from a bipolar shaper. With its power of 2 mW per channel the ASIC measures, on a CZT sensor connected and biased, charges up to 100 fC with an electronic resolution better than 200 e- rms. Our preliminary spectral measurements applying a simple cathode/anode ratio correction demonstrated a single-pixel resolution of 4.8 keV (0.72 %) at 662 keV, with the electronics and leakage current contributing in total with 2.1 keV.

The application of the capability of low-temperature poly-Si TFT circuits for high resolution X-ray active matrix sensor is explored. The integration of poly-Si TFT circuits on the glass enables an easy connection for the sensor array with fine pixel pitch. A novel charge sensitive amplifier circuit employing poly-Si TFTs is proposed for the readout system of the active matrix sensor. It can considerably increase the circuit’s immunity to the unavoidable threshold voltage variations of the poly-Si TFTs. The V TH mismatch effect of the TFTs, which results in the offset voltage of the charge amplifier, can also be suppressed by the proposed circuit. However, the noise arisen from the V TH mismatch can be even larger than that from the V TH variation after compensation. It reflects that, for higher bit digital X-ray image sensors, the mismatch effect of the devices must be properly taken into consideration.

A flexible technology for microfluidic applications using piezoelectric polyvinylidene fluoride (PVDF) and polydimethylsiloxane (PDMS) was developed. The flexible piezoelectric PVDF detects the flow rates and impulse pressure signal using piezoelectric characteristics. This study uses microelectromechanical systems (MEMS) technology to fabricate the sensing patterns on PVDF sheets, designs a molding transfer to form the microfluidic channels of the PDMS, and integrates them together. Experimental results show that PVDF films has good piezoelectricity at stretching ratio of 4, the flow rates ranged from 100 to 450 mL/min at dynamic controlling sensing, the miniature curvature radius is about 3 cm, and the cross section of the flexible microchannels is about 200 times 200 mum2. The feasibility studies show that molding transfer is an appropriate low-cost technology for fabricating the flexible piezoelectric channels. The PVDF can be easily manufactured using MEMS process because it has a good mechanical strength and electrochemical stability in polymers.

An inverse method of identification for the determination of material parameters that are used for the FEM simulation of milling processes is proposed. First of all, a special device has been instrumented and calibrated to perform force and torque measures, directly during milling experiments in using a piezoelectric dynamometer and a high frequency charge amplifier. The experimental results were saved and low pass filtered to obtain a data measured basis reliable and accurate. Then FEM simulations of milling were performed using explicit ALE based FEM code. The material behaviour is firstly described from a Johnson-Cook constitutive law and different characterization test have been lead in a wide range of conditions to be use to identify a new behaviour law adapted to the process. A fracture model was also added to consider chip formation and separation. Finally, identification procedures are proposed for the determination of material law parameters. These procedures are based on an objective function to minimize, firstly defined by the experimental and numerical results obtained in the turning process and secondly by the experimental and analytical results obtained in milling process. The identification approach is mainly based on the Surfaces Response Method in the material parameters space, coupled to a sensitivity analysis. A Moving Least Square Approximation method is used to accelerate the identification process. This method of identification is here applied for a 304L stainless steel and the first investigations are presented.

This brief presents a method to exploit gate leakage (GL) to create a feedback element for an input offset insensitive and output offset programmable inverting amplifier. Measurements are shown from a test circuit produced in a 90-nm multithreshold CMOS process where a GL element uses thin oxide and a amplifier input stage uses thick oxide. The feedback element has very high nonlinear impedance from about 100 M to several gigaohms depending on the applied voltage, and is suitable for adaptive applications where long time constants (1 ms to 1s) are required and small, slowly wandering offsets can be tolerated.

In the present paper a piezoelectric actuator realized for interferometric applications is described, together with a numerical model to simulate its electro-mechanical behavior. The actuator is an open-loop device made up of three piezoelectric ceramics glued into a stainless steel case and connected directly to the parallel port of a personal computer by control electronics developed on purpose. It consists of a 16 bit digital-to-analog converter whose voltage is fixed by the parallel port, a charge amplifier which provides the voltage to the piezoelectric ceramics and a current divider for the control of the voltage on each channel. The layout based on three active elements has allowed to obtain a device which is able to perform a straight expansion with a negligible tilting, a desirable feature for an actuator used for interferometric applications. The hysteretic behavior, a typical characteristic of this kind of actuator, was simulated by a numerical model, based on the Prandtl–Ishlinskii hysteresis operator, which shows a high capability to predict the input–output response at any level of the input signal, and it is efficient enough for use in real-time applications.