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Home-based health care applications are rapidly gaining popularity, enabling a renewed focus on the design of low-power and low-noise front-end circuitry. In this context, the evaluation of low-frequency biomedical signals, such as the respiration pattern, benefits from the design of a front-end amplifier with reduced power consumption and low noise. Continuous efforts on improving the performances of respiration-monitoring devices have resulted in the reduction of noise and motion artefacts by increasing complexity (e.g. complex algorithms or high precision filtering) at the expense of increased power consumption. This study is focused on the design of a fully integrated charge amplifier for respiration monitoring based on a pyroelectric sensor. Simulation and test results show a power consumption of 1.8 µW, an active die area of 0.085 mm 2 , a bandwidth in the range from 10 mHz to 13 kHz, and a remarkable noise efficiency factor of ∼2.79, which fits well with the development of an energy efficient wearable device.

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.

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.

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.

Abraham Bennet, the inventor of the leaf electroscope, devised a three-plate procedure for doubling electric charge. Like so many other manual processes in the 18th century it was ripe for deskilling by mechanisation, and it was William Nicholson who mechanised it. Here, the author describes a replica of Nicholson's doubler which he has constructed and the difficulties he encountered in making it perform in the manner described by Nicholon.

The author explains how a device small enough to fit inside a car's rear-view mirror can be programmed to see. The device is a CMOS based image sensor developed by VLSI Vision Ltd., Edinburgh. The sensor overcomes the previous problem of placing all pixel outputs through a single charge amplifier by using a separate charge-sense amplifier at the head of each column of pixels. The author describes how the sensor operates. The incorporation of this sensor into a programmable machine-vision system called the imputer is discussed.

A charge compensation technique is proposed for switched capacitor stages with low-gain opamps. It cancels the error charge flow during the operation phase, thus enhancing the accuracy. A capacitive T-network can be employed to implement the resulting large capacitor ratio. A switched-capacitor integrator and a sample-and-hold stage were designed and simulated to verify the proposed technique.

The offset-voltage compensation technique is proposed for an accurate current-source circuit. This current source is made of a transistor, a resistor, and operational amplifier feedback in order to achieve a high output resistance as well as high accuracy of a generated current signal. Discrepancy from the ideal value mainly results from the offset voltage of the operational amplifier. The transconductance amplifier is utilised with a feedback loop that is controlled by the switched-capacitor integrator. The proposed technique is incorporated in the light-emitting diode driver circuit applications and successfully verified with hardware measurement.

Proposed is a 14.3-bit extended counting analogue-to-digital converter (ADC) with built-in binning function for medical X-ray CMOS imagers. To reduce the area and improve the image resolution simultaneously, the proposed ADC internally performs the analogue binning operation without a charge amplifier. The ADC also uses an extended input range to realise true 14-bit dynamic range when applying the digital correlated double sampling technique. The proposed ADC was fabricated using a 0.35 µm CMOS process and the measured differential and integral nonlinearities of the 14.3-bit ADC are +0.97/−0.79 and +2.79/−1.70 LSB, respectively.

A novel current-feedback operational amplifier, the input stage of which is based on the design and use in a repeated pattern of a current-transfer cell, exhibits performance characteristics superior to those obtained with an established input architecture: in particular, the common-mode rejection ratio (CMRR) is 105 dB, and the DC offset voltage less than 200 µV.

A piezoelectric pressure sensor is presented which consists of a GaAs MESFET in which the transverse piezoelectric effect is used to charge the gate pad. The MESFET itself acts as an integrated charge amplifier. The sensor gives output signals which are comparable to those of a much bulkier commercial measurement system. The sensitivity achieved is 200 mV/bar in the range 0 – 20 bar.

A novel front-end circuit for capacitive sensors and switched-capacitor (SC) circuits is presented. In this circuit charge is transferred to an input integrator circuit in a controlled way to prevent overload of the input amplifier. Application of this technique extends the linear range for large input signals.

A CDS readout circuit for CMOS active pixel sensor (APS) imagers is presented. The proposed CDS circuit is simple, requires only one output amplifier, and is based on capacitor ratios, reducing the column fixed pattern noise.

A low noise, low power CMOS charge preamplifier with DC coupling to particle silicon detectors has been designed. Simulation results show that the detector leakage current can be compensated up to 8 µA. The proposed charge amplifier has been simulated and implemented with a CMOS silicon-on-insulator process. A total RMS output noise voltage of 0.58 mV for a detector capacitance of 10 pF and a DC leakage current of 5 µA and a conversion gain of 2.86 mV/fC with 0.66 mW power consumption have been obtained.

An alternative implementation for emulating an active inductor is proposed. Based on a classical gyrator active inductor architecture, the new active inductor is implemented by using a log-domain current integrator instead of a voltage integrator. Inductance and Q-factor can be tuned independently. Simulation results confirming the idea are shown. The proposed circuit is a micropower active inductor operating in the weak inversion region of the MOSFETs.

A novel amplifier structure that compensates nonlinearities by means of a special type of feedback is proposed. The high linearity performance is combined with a high gain that is unreachable with the conventional feedback structure. A practical configuration of the structure is given as an improvement over both a conventional feedback amplifier and a typical feedforward amplifier. Experimental results are provided to verify the high linear characteristic of the practical structure.

0This amplifier is intended to be part of the front-end of a larger read-out chip to be used with particle detectors. The demands of read-out electronics are low power, low noise and high speed. At the input a charge pulse of 25000 electrons (4fC) is applied to study the behaviour of the amplifier. The amplifier has a gain of /spl plusmn/12 mV/fC depending on the biasing condition, a peaking time of 35 ns and a power consumption of

The input circuit of a charge-coupled device has the form of an m.o.s.f.e.t. Linear charge injection has been achieved by the negative feedback caused by a capacitor connected in series with the equivalent source electrode. The capacitor charge is reset between each sampling event. The distortion is similar to that obtained with fill-and-spill techniques, and the input voltage amplitude is more convenient.

In systems with signal-error feedforward, the recently suggested method of compensated signal takeoff can be used to extend the improvement of feedforward control to the output signal adder. A system using this quasifeedforward is compared with a feedback system consisting of similar components. The dynamic stability and the improvement obtained with both control methods are analysed.

The exact mathematical solution of the amplifier finite gain and bandwidth problem in switched-capacitor filter networks is presented. The theory is incorporated into a computer analysis program and typical results for a filter circuit are included.

In this communication we propose a new active-RC ideal integrator structure using two operational amplifier active elements. Novelties in the proposed circuit are the realisability of a very large time constant that is independently controllable by single resistor at low sensitivities, dual input capability, and use of a grounded capacitor—a feature desirable for microcircuit fabrication.

The letter describes a single stage operational transconductance amplifier (OTA) with cascoded output transistors, designed for micropower switched-capacitor filters. The device features high voltage gain (>90 dB) under capacitive load, large output swing, very low power consumption (5 µW at 3 V supply voltage for 100 kHz bandwidth with 10 pF load) and reduced circuit area (