Peak Detector Circuit Research Articles

Real Time Electronic Feedback for Improved Acoustic Trapping of Micron-Scale Particles.

Acoustic differential extraction has been previously reported as a viable alternative to the repetitive manual pipetting and centrifugation steps for isolating sperm cells from female epithelial cells in sexual assault sample evidence. However, the efficiency of sperm cell isolation can be compromised in samples containing an extremely large number of epithelial cells. When highly concentrated samples are lysed, changes to the physicochemical nature of the medium surrounding the cells impacts the acoustic frequency needed for optimal trapping. Previous work has demonstrated successful, automated adjustment of acoustic frequency to account for changes in temperature and buffer properties in various samples. Here we show that, during acoustic trapping, real-time monitoring of voltage measurements across the piezoelectric transducer correlates with sample-dependent changes in the medium. This is achieved with a wideband peak detector circuit, which identifies the resonant frequency with minimal disruption to the applied voltage. We further demonstrate that immediate, corresponding adjustments to acoustic trapping frequency provides retention of sperm cells from high epithelial cell-containing mock sexual assault samples.

Single-chip Implementation of LVDT Signal Conditioning

The aim of this work was to prove that the signal conditioning electronics for linear variable transformers (LVDTs) can be implemented in inexpensive, general-purpose 8-bit microcontrollers, making expensive dedicated signal conditioning chips redundant. A low-cost, high-resolution signal conditioning solution for LVDTs is presented. Apart from a few external passive components, the entire solution is implemented in a low-cost, analog-digital hybrid microcontroller. The excitation sinusoid is generated by filtering out the fundamental frequency of a (self-sustained) pwm-generated square wave and the secondary coils’ signals are demodulated with classic peak detector circuits implemented in the microcontroller using a combination of its embedded analog and digital building blocks. A resolution of 1 m over a range of ±6.35 mm for a commercial LVDT is reported and an uncertainty of 6 m in the absolute value is deduced. The entire solution is implemented as surface mounted components on a small printed circuit board and the LVDT core displacement is displayed on an LCD display. Due to the simplicity and low-cost components required, this signal conditioning proposal has the potential to have a significant impact on commercial LVDT signal conditioning chips in the future since it is significantly less expensive than the present state-of-the-art signal conditioning chips offered by the main commercial suppliers and other solutions previously suggested in scientific literature.

ENGINEERING OF ACOUSTIC TECHNOLOGY FOR UNDERWATER POSITIONING OBJECT

Underwater Positioning System (UPS) is a system to track the existence of the position of an object by utilizing the arrival time of the signal measurement. On land, the system uses an electromagnetic signal called GPS. However, because it cannot penetrate water effectively, an acoustic signal is used as an alternative. The purpose of this research is to engineer the control system of data acquisition and underwater acoustic device to measure arrival time (TOA) and apply equation model for underwater sound source positioning system. the effective frequency resonance of the transducer and the hydrophone is at a frequency of 6 kHz. The acquisition control device is able to measure the TOA signal with an error on a digital channel smaller than an analog channel. The difference between the TOA values measured by oscilloscope and acquisition control system is caused by inaccuracy of threshold estimates at the receiver's peak detector circuit. The position of the sound source coordinates obtained from the equation model shows the highest difference in depth point (z) compared to points (x) and (y), caused by the equation model used is limited to four hydrophone units forming a horizontal baseline.

Digital design of internal device of electro-magnetism excitation positioning for electronic capsule

Objective To develop a digital signal processing method for magnetic positioning of electronic capsules according to the theory of multiple alternating magnetic field source electromagnetic positioning, so as to reduce the volume and power consumption of electronic capsules. Method Based on STM32 MCU, software algorithms such as fast digital filtering, peak detection and frequency detection were designed to replace the corresponding analog hardware circuits such as analog filtering, peak detection and comparison circuits. Results The experimental results showed that the average relative error of the peak detection and frequency detection of the digital signal processing system were 1.51% and 0.28%, respectively. The linear relationships of theoretical amplification factor and actual amplification factor of the programmable amplifier were basically consistent, and the average ratio difference was 4.51 dB. Conclusions The proposed digital signal processing system can replace some analog hardware circuits, providing a basis for reducing the size and power consumption of electronic capsules. Key words: Electronic capsules; Magnetic positioning; Frequency division incentive; Digital filtering; STM32

An Efficient Self-Powered Piezoelectric Energy Harvesting CMOS Interface Circuit Based on Synchronous Charge Extraction Technique

An efficient self-powered synchronous electric charge extraction CMOS interface circuit dedicated to piezoelectric harvesters is proposed in this paper. Self-powered peak detection (PKD) and switch circuits are used to reduce quiescent current so that the backup or pre-charged power can be saved. A new low phase lag (LPL) PKD circuit is designed to improve the synchronous extraction efficiency, which only requires one detection capacitor to perform positive and negative PKD. The circuit can be set at general mode (G-mode) or LPL mode (LPL-mode). Under LPL-mode, the phase lag can be reduced typically by 50%, the synchronous extraction efficiency can obtained up to 94%, while the output power can reach 659 μW when the piezoelectric transducer original opencircuit voltage Voc,org = 5 V, which is 3.56 times of that of full-bridge rectifier standard energy harvesting circuit at the maximum power point. The minimum harvesting startup voltage is 1.7 V and is independent of the energy storage capacitor voltage VDC. The harvesting efficiency can still reach 71.3% at Voc,org = 5 V. The size of the active area is 0.5 mm2 in a 0.18-μm CMOS technology. Circuit may be invoked as a functional block for energy autonomous wireless sensor network node of the Internet of Things.

Development of hard X-ray spectrometer with high time resolution on the J-TEXT tokamak

A hard X-ray (HXR) spectrometer has been developed to study the runaway electrons during the sawtooth activities and during the runaway current plateau phase on the J-TEXT tokamak. The spectrometer system contains four NaI scintillator detectors and a multi-channel analyzer (MCA) with 0.5ms time resolution. The dedicated peak detection circuit embedded in the MCA provides a pulse height analysis at count rate up to 1.2 million counts per second (Mcps), which is the key to reach the high time resolution. The accuracy and reliability of the system have been verified by comparing with the hardware integrator of HXR flux. The temporal evolution of HXR flux in different energy ranges can be obtained with high time resolution by this dedicated HXR spectrometer. The response of runaway electron transport with different energy during the sawtooth activities can be studied. The energy evolution of runaway electrons during the plateau phase of runaway current can be obtained.

DFB laser diode interferometer with image capture timing control for surface profile reconstruction

A DFB laser diode interferometer with sinusoidal phase modulation (SPM) and image capture timing control was proposed for the reconstruction of surface profile. Sinusoidal phase modulation was achieved by controlling the injection current of light diode. The surface profile was reconstructed on four consecutive fringe images. Random phase error and low-frequency phase shift would be superposed on the interference fringes due to external disturbances such as mechanical vibration and temperature fluctuation. A simple peak detection circuit that would take less time consumption than phase generated carrier (PGC) was built for eliminating external disturbances, and the phase of fringe image could be stabilized in about one millisecond, which is conducive to real-time surface profile reconstruction. A novel method to capture four consecutive fringe images in adjacent modulation period was presented by controlling pulse sequence to trigger camera exposure and image readout operation. The whole system was tested on an optical table without vibration isolation and being kept in thermostatic chamber. The repeatability was about 0.018 wave (approximately 14nm for 760nm wavelength). The feasibility for high-resolution surface profile reconstruction had been verified.

Design of Frequency and Amplitude of Sine Wave Measurement Circuit Based on MSP430

Sine wave signal is a kind of typical electronic technology signal waveform, and frequency, amplitude and phase are three elements of the sine wave respectively. In order to measure the elements more accurately, scientific research methods is adopt in the design. Based on high precision of peak detection circuit combined with MSP430 MCU, the circuit for measuring frequency and amplitude of sine wave signal is implemented, and the results could be shown in the display circuit at the same time. The circuit can work within the 1kHz - 20kHz and 240mV - 5V sine wave signal, and has display circuit, which can display accurate measurement results, to achieve human-computer interaction.

Self-powered optimized synchronous electric charge extraction circuit for piezoelectric energy harvesting

This article presents a self-powered interface circuit for the optimized synchronous electric charge extraction technique applied to piezoelectric vibration energy harvesting. A peak detector circuit is developed to detect the maximum and minimum vibration displacements and drive the electronic switches synchronously. This approach does not require additional piezoelectric elements to power the electronic interface itself for which a detailed analysis and a simple model are proposed to give a better understanding on the working principle. Finally, the influence of the switching phase lag and the peak detector power consumption on the harvested power is studied. Experimental studies are conducted and successfully compared with the theoretical approach.

Two self-powered energy harvesting interfaces based on the optimized synchronous electric charge extraction technique

Optimized synchronous electric charge extraction (OSECE) interface is a load weakly-dependant circuit, which is a favorable characteristic for piezoelectric wideband vibration energy harvesting. However, it introduces synchronous switches that need to be self-powered in a stand-alone system. This paper presents the design and experimental testing of two self-powered approaches for the OSECE technique. One is made of electronic switches driven by analog peak detector circuits; the other uses mechanical switches directly controlled by the ambient vibrations. Finally, advantages and drawbacks of the two approaches will be compared and discussed.

A method to measure the micro-capacitance for MEMS comb actuators

A method is introduced to measure the micro-capacitance for MEMS comb actuators whose value is in pF even fF magnitude. This method uses so called peak detection measuring technology to realize this purpose. It is mainly composed of the signal generating circuits, C/V (Capacitance/Voltage) converting part, peak detector circuits and the digital solution element. In order to verify the correctness of the design, detailed theory analysis and simulation are made for every composed portion and corresponding mathematical model is built. It is concluded from the analyzed result that precision of the system can reach 237 aF for 0.98–2 pF measuring range. When corresponding measuring electric circuits is fabricated and debugged, high precision calibration device named Agilent E4980A is used to calibrate it. It is concluded from the calibrated result that the output voltage of the measurement circuit and the micro capacitance have good linear relationship, which verifies the correctness of the pertinent theory. Finally, in order to verify the correctness of the design, dynamic characters of a resonant MEMS gyroscope, which is fabricated with bulk technology and bonding process, is tested with this device. It is concluded from the measured result that relative error of the resonant frequency between the ideal value and the measured result is just 0.02%. Quality factor of this sensor is 312.5. Experimental results indicate this scheme is feasible to measure the static and dynamic characters of micro capacitors.

Design of New Metal Detector

Metal detector is used more and more widely in the modern social life, it acquires much attention because of its powerful detection capabilities. This article introduces the design and implementation of an intelligent metal detector which is based on TMS320LF-2407.Adopt giant magneto resistive (GMR) sensor with the type of AA006-02. Describe the hardware component, software design, working principle and main functions of the system in detail. The core of the whole contains the probe design and control circuits. The probe: oscillator circuit is constituted by the 555 timer, it provide the sine wave signal for the coil. The control circuits: the signal which is collect by the GMR sensor is processed by voltage amplifier and filtering circuit, the peak detection circuit and A / D conversion, The signal can accurately reflect the characteristic parameters of the received signal, stability, and can eliminate interference.Practice shows that this metal detector with the method can greatly reduce the malfunction rate on the base of meeting the sensitivity.

5-Gb/s Peak Detector Using a Current Comparator and a Three-State Charge Pump

A 5-Gb/s current-mode peak detector is proposed using a V-I converter, a current comparator, and a charge pump with three states (i.e., UP, DN, and HOLD). It eliminates the problem that a voltage error increases with an input data rate in a conventional peak detector circuit. In this brief, the voltage error between the measured input and output peak voltages is smaller than 5% for a pseudo-random binary sequence signal at a data rate up to 5 Gb/s, with an input voltage swing up to ±500 mV and an input common-mode voltage of 0.9 V. A chip fabricated in a 0.18-μm process gives the power consumption of 2.7 mW at a voltage supply of 1.8 V and a chip area of 150 μm × 120 μm.

A 4-$\mu\hbox{W}$ CMOS Front End for Particle Detection Applications

A complete low-power front end for particle detection applications is presented. The front end integrates a charge-sensitive amplifier with a novel adaptive biasing scheme that allows the dc bias currents to be scaled below conventional limits. A downstream peak detector circuit captures the peak value for each detection event, which is then fed to an integrated analog-to-digital converter (ADC). The event-driven ADC is shut off in between detection events to further reduce power consumption. The circuit has been fabricated using a 0.18- μm CMOS technology, with a power consumption ranging between 4 and 20 μW, depending on the particle detection rate. This low-power operation facilitates the development of compact long-life battery-powered remote particle sensors.

A Novel Low Power, Variable Resolution Flash Analog-to-Digital Converter

In this paper, a new low power and variable resolution flash ADC is proposed. Comparators of conventional flash ADC are replaced with CMOS inverters whose threshold can be varied dynamically. A novel peak-detector circuit is employed to achieve variable resolution as well as to switch the unused parallel inverters to standby mode. Linear reduction in resolution leads to exponential reduction in power. The ADC is capable of operating at 4-bit, 6-bit, and 8-bit precision and at a supply voltage of 2.5 V, it consumes 21.5 mW at 8-bit, 9 mW at 6-bit and 3.5 mW at 4-bit resolution. The sampling frequency ranges from 0.8 to 1.6 GSPS, and the ADC has a DNL < ±0.4 LSB, INL < ±0.36 LSB, SNR of 47 dB and SNDR of 46.3 dB for 8-bit operation. The proposed 'inverter-based' flash ADC operating at 8-bit precision and conventional 8-bit comparator-based flash ADC have been designed, compared and verified for post layout simulations in standard 65 nm CMOS technology.

A Dual Modality Gamma Camera Using ${\rm LaCl}_{3}({\rm Ce})$ Scintillator

Portable gamma-ray imaging devices capable of responding to a broad energy range while providing reasonable angular resolution and efficiency are useful in a number of applications, including environmental remediation and industrial surveys. Due to this, a dual radiation imaging system that combines the advantages of a multi-aperture mechanical collimator with electronic-collimation has been designed, built, and tested. The combination of these two disparate imaging modalities offers both efficiency and good angular resolution, and is unique since a single gamma ray can contribute information to both modalities simultaneously. The dual modality gamma camera (DMGC) combines a high-resolution uniformly redundant array (URA) coded aperture with a Compton scatter camera to provide a broader range of energy response suitable for a wider range of industrial applications. The LaCl3(Ce) in the first detector module has 22times22 voxels, each voxel having a dimension of 2times2times5 mm3. The LaCl3(Ce) in the second detector module has 6times6 voxels having dimensions of 4times4times10 mm3. Both scintillators are coupled to position-sensitive photomultiplier tubes (PSPMT). The front-end, peak detection and coincident circuits of the DMGC are custom-designed for simplicity and compactness. Point and simulated ring radiation sources at intermediate energies (356 and 662 keV) are measured for mechanical, electronic and dual collimation and the reconstructed images are compared. The results show that the combined dual collimation image, using the maximum likelihood method for image reconstruction, yields better images than either a mechanical or an electronic collimation image at intermediate energies.

Fast Photoacoustic System Based on an Acoustic Lens and the Peak Detection Technology

A fast photo-acoustic (PA) imaging system was developed and tested on phantom sample, which consists of an acoustic lens，a multi-element linear transducer array, and the peak detection circuit. The multi-element linear transducer array consists of 64 elements. By utilizing an acoustic lens, the PA signals generated from the sample are imaged and detected by a multi-element linear transducer array, which directly changes the PA signals into the homologous electronic signals. Thus we can map the image more rapidly, with the peak detection circuit, which was designed specially. Compared to other exiting technology and algorithm, the PA imaging system based on an acoustic lens and the peak detection technology was characterized with speediness and real-time. The images reconstructed in this experiment have high definition and resolution，and may have potential for developing an appliance for clinical diagnosis.

CMOS integrated pixel array for low-level radiation detection using ‘time compression’ parametric amplification

In this work, theoretical modeling and simulations of a ‘time compression’ parametric amplification pixel array to be used in CMOS imaging for low-level or near IR radiation are presented. The implementation in the higher resistivity substrate process used for smart-power devices, namely the 30 V thin-film 1.0 μm SIMOX-CMOS based on Silicon-on-Insulator technology, enables isolated separation of photoactive and readout circuitry areas when integrated on the same chip. The method presented shows that very high readout current peaks can be generated which are much higher than the mean value of the photocurrent induced. Thus, the parametrically amplified readout signals can be detected by a low-noise peak-detector circuit. The 500×500 μm 2 area pixels with internal parametrically controllable amplification and increased pixel fill-in factor (>90%) present higher detection volume due to enlarged deep-depletion region depth caused by a low resistivity substrate. Moreover, the X– Y addressing and the inverse exponential dependence of the parametric amplification on the incoming radiant flux for each pixel provide separately controllable single-pixel internal amplification which improves the intra-scene high dynamic range demands.

A transient noise model for frequency-dependent noise sources

Transient noise simulations are beneficial to design analog circuits, such as peak detection circuits for detecting very small signal levels, or circuits having large gains to be saturated by noise signals. Though the noise characteristics of these circuits can be simulated with SPICE in frequency domain, the dynamic noise performance cannot be shown with noise analysis in frequency domain. The transient noise model for white noise such as thermal noise of the resistor can be generated in time domain with Gaussian distributed random numbers, because the white noise is independent of frequency. But the transient noise model for frequency-dependent noise sources such as 1/f noise is hard to generate in the time domain. In this paper, a transient noise model for frequency-dependent noise sources is presented, and its application is shown.

Analog peak detector and derandomizer for high-rate spectroscopy

A compact and accurate readout system has been developed for high-rate spectroscopy with multi-element detectors. The fully self-triggered system multiplexes the signals from 32 detectors into a novel peak detector, which also serves as a derandomizer. The captured pulse heights are stored as analog samples before being presented to the ADC along with the corresponding channel addresses. The peak detector incorporates a new two-phase configuration that cancels offsets and other errors found in conventional designs. Offset cancellation gives the peak detector rail-to-rail sensing and driving capability and permits two or more peak detectors to be operated in parallel to serve as a data-driven analog memory. First experimental results on the new peak detector and derandomizer (PDD) circuit, fabricated in 0.35 /spl mu/m CMOS technology, include a 0.2% absolute accuracy for pulses with 500-ns peaking time, 2.7-V linear-input range, 3.5-mW power dissipation, 250-mV/s droop rate, and negligible dead time. We have tested the system with 32 CZT detectors and a /sup 241/Am source. The spectra collected from the 32-channel system show that the noise performance of the preamp/shaper is not degraded by the multiplexing, peak detecting, and derandomizing operations.