Wireless Preamplifier for the Specimen Current Mode Detector in a SEM

Using a scanning electron microscope (SEM) in the back-scattered electron (BSE) mode the composition of multi-element specimens may be determined based on the strong dependence of emission coefficient η on the average atomic number of elements Z. The output video signal of the usual BSE detectors is produced from their sensors, and the larger proportion of high-energy electrons with modified spectrum is added. Since η = is/ip (is and ip currents of specimen and probe), better accuracy must be achieved by direct measurements those currents on the specimen surface. Here, an experimental model of a current detector for a presented specimen is described. The cage is mounted on the carousel of the moving specimen stage. The input of the preamplifier is connected to the specimen holder in the form of a disk, the diameter of which is 12 mm. When the probe along its surface scanned, the input potential begins to pulsate with a negative polarity. The output of this preamplifier is connected to a small light-emitting diode, which creates intensity-modulated radiation in the chamber. Thus created the light video signal will be picked up by the photomultiplier of the E-T detector. The modes of true SE and BSE are set by applying tens bias volts of various polarities to the specimens or the cage itself.

Simulation of a Monolithic Integrated CMOS Preamplifier for Neural Recordings

A monolithic integrated CMOS preamplifier is presented for neural recording applications. Two AC-coupied capacitors are used to eliminate the large and random DC offsets existing in the electrode-electrolyte interface. Diode-connected nMOS transistors with a negative voltage between the gate and source are candidates for the large resistors necessary for the preamplifier. A novel analysis is given to determine the noise power spectral density. Simulation results show that the two-stage CMOS preamplifier in a closed-loop capacitive feedback configuration provides an AC in-band gain of 38.8dB,a DC gain of 0,and an input-referred noise of 277nVmax, integrated from 0. 1Hz to 1kHz. The preamplifier can eliminate the DC offset voltage and has low input-referred noise by novel circuit configuration and theoretical analysis.

A 10Gb/s GaAs PHEMT High Gain Preamplifier for Optical Receivers

A high gain cascade connected preamplifier for optical receivers is developed with 0.5μm GaAs PHEMT technology from the Nanjing Electronic Devices Institute. To begin with, the transimpedance amplifier has a -3dB bandwidth of 10GHz, with a small signal gain of around 9dB. The post-stage distributed amplifier （DA） has a -3dB bandwidth of close to 20GHz,with a small signal gain of around 12dB. As a whole,the cascade preamplifier has a measured small signal gain of 21.3dB and a transimpedance of 55.3dBΩ in a 50Ω system. With a higher signal-to-noise ratio than that of the TIA and a markedly improved waveform distortion compared with that of the DA, the measured output eye diagram for 10Gb/s NRZ pseudorandom binary sequence is clear and symmetric.

10Gb/s GaAs PHEMT Current Mode Transimpedance Preamplifier for Optical Receiver

A single power supply common-gate （CG） current mode transimpedance preamplifier （TIA） is developed with a 0.5μm GaAs PHEMT process. The amplifier has a measured - 3dB bandwidth of 7. 5GHz and a transimpedance gain of 45dBΩ. Both the input and output voltage standing wave ratios （VSWR） are less than 2 within the bandwidth. The equivalent input noise current spectral density varies from 14.3 to 22pA/√Hz, with an average value of 17. 2pA/√Hz. Having a timing jitter of 14ps and eye amplitude of about 138mV,the measured output eye diagram for 10Gb/s NRZ pseudorandom binary sequence （PRBS） is clear and satisfactory.

Design of 10 Gbit/s burst-mode transimpedance preamplifier for PON systems

A 10 Gbit/s burst-mode preamplifier is designed for passive optical networks （PONs）. To achieve a high dynamic range and fast response, the circuit is DC coupled, and a feed-back type peak detector is designed to perform auto-gaincontrol and threshold extraction. Regulated cascade （RGC） architecture is exploited as the input stage to reduce the input impedance of the circuit and isolate the large parasitic capacitance including the photodiode capacitance from the determination pole, thus increasing the bandwidth. This preamplifier is implemented using the low-cost 0. 13 ixm CMOS technology. The die area is 425 μm × 475 μm and the total power dissipation is 23.4 mW. The test results indicate that the preamplifier can work at a speed from 1.25 to 10.312 5 Gbit/s, providing a high transimpedance gain of 64.0 dBΩ and a low gain of 54. 6 dBl2 with a dynamic input range of over 22.9 dB. The equivalent input noise current is 23. 4 pA/ Hz1/2. The proposed burst amplifier satisfies related specifications defined in 10G-EPON and XG-PON standards.

Compact 16-channel integrated charge-sensitive preamplifier module for silicon strip detectors

In this study,a compact 16-channel integrated charge-sensitive preamplifier named the smart preamplifier(SPA)was developed to support the large-scale detector array used in modern nuclear physics experiments.Two types of SPA,namely SPA02 and SPA03(with external field effect transistor),have been manufactured to match silicon detectors with small and large capacitances,respectively.The characteristics of the SPA include fast response of typically less than 6 ns for pulse rising time and low equivalent noise of 1.5 keV at zero input capacitance.The energy sensitivity and pulse decay time can be easily adjusted by changing the feedback capacitance Cfand resistance Rfin various applications.A good energy resolution of 24.4 keV for 5.803-MeV alpha particles from 244 Cm was achieved using a small-sized Si-PIN detector;for the silicon strip detectors in the test with the alpha source,a typical energy resolution of 0.6–0.8%was achieved.The integrated SPA has been employed in several experiments of silicon strip detectors with hundreds of channels,and a good performance has been realized.

Design of a Preamplifier Card for the Photomultiplier Tubes of a Gamma Camera

The service provided by the GC(Gamma Cameras)in the Nuclear Medicine departments fails because of their breakdown,generally due to the associated electronics and not to the physical detection components.For this reason,it was decided to develop an electronic system that allows the recovery and optimization of disused GC,starting with the design of the preamplifier for a PMT(photomultiplier tube).The circuit was designed and simulated and the list of components necessary for the construction of the preamplifier was generated,as well as the printed circuit board was designed for its assembly.By simulating the preamplifier this worked in linear mode.This determines that the amplitude of the output signal is proportional to the amount of charge delivered by the detector.This card allows an automatic adjustment of the signals of the PMT as do the modern GC.

High-Stability High-Energy Picosecond Optical Parametric Chirped Pulse Amplifier as a Preamplifier in Nd：Glass Petawatt System for Contrast Enhancement

We demonstrate a novel picosecond optical parametric preamplification to generate high-stability, high-energy and high-contrast seed pulses. The 5ps seed pulse is amplified from 60pJ to 300μJ with an 8.6ps/ 3mJ pump laser in a signal stage of short pulse non-collinear optical parametric chirped pulse amplification. The total gain is more than 106 and the rms energy stability is under 1.35%. The contrast ratio is higher than 10s within a scale of 20ps before the main pulse. Consequently, the improvement factor of the signal contrast is approximately equal to the gain 106 outside the pump window.

High Performance Bilinear Differential Preamplifier for BESⅢ Time-of-Flight System

A time-of-flight (TOF) detector has been used in the BESIII experiment to provide charged particle identification. In this paper, we present a novel high performance differential amplifier, which has been designed for amplifying the signals from the detectors. The preamplifier can amplify differential signals, which can help to eliminate the common mode pickup, and increase the signal-to-noise ratio (SNR). Bilinear gain is one of the features of this preamplifier, which greatly increases the dynamic range and avoids the dead time of the preamplifier. In order to describe the bilinear gain, a 4-parameter function is developed. And this 4-parameter function can also be used in the calibration of the time walk caused by the amplitude due to the bilinear gain. The preamplifier has a gain about 10V/V with a small signal and about 1.0V/V with a large signal. The rise time of the preamp is less than 2 ns.

A low noise and wide dynamic range preamplifier for HPGe detectors

Purpose HPGe detectors can be used for both dark matter search and neutrinoless double beta decay experiments.However,signal amplitudes of these two experiments are quite different.This paper presents the development of a wide dynamic range CMOS preamplifier for HPGe detectors,which can also be used for low light level photon detection.Methods The structure of a dual-stage dual-gain amplifier was adopted to receive the signals with charges ranging from~0.01 fC to 500 fC.A novel“pre-reset”technique has been proposed to reduce the dead time ratio for large signals.A prototype chip was fabricated and tested.Results A minimum ENC of 43 electrons has been achieved for the high-gain channel at 77 K and the maximum charge of the input signal could be up to 500 fC for the low-gain channel,corresponding to a dynamic range above 90 dB.Conclusions The dual-gain structure of the preamplifier and the“pre-reset”method have been successfully verified,which can be used for HPGe detectors for dark matter and neutrino experiments in the future.

SNR Improvement of QEPAS System by Preamplifier Circuit Optimization and Frequency Locked Technique

Preamplifier circuit noise is of great importance in quartz enhanced photoacoustic spectroscopy （QEPAS） system. In this paper, several noise sources are evaluated and discussed in detail. Based on the noise characteristics, the corresponding noise reduction method is proposed. In addition, a frequency locked technique is introduced to further optimize the QEPAS system noise and improve signal, which achieves a better performance than the conventional frequency scan method. As a result, the signal-to-noise ratio （SNR） could be increased 14 times by utilizing frequency locked technique and numerical averaging technique in the QEPAS system for water vapor detection.

High performance power-configurable preamplifier in a high-density parallel optical receiver

A power-configurable high performance preamplifier was implemented in standard 180-nm CMOS technology for 12 × 10 Gb/s high-density ultra-high speed parallel optical communication system. With critical limitations on power consumption, area and fabrication cost, the preamplifier achieves high performance, e.g. high bandwidth, high trans-impedance gain, low noise and high stability. A novel feed-forward common gate （FCG） stage is adopted to alleviate contradictions on trans-impedance gain and bandwidth by using a low headroom con- suming approach to isolate a large input capacitance and using complex pole peaking techniques to substitute induc- tors to achieve bandwidth extension. A multi-supply power-configurable scheme was employed to avoid wasteful power caused by a pessimistic estimation of process-voltage-temperature （PVT） variation. Two representative sam- ples provide a trans-impedance gain of 53.9 dBf2, a 3-dB bandwidth of 6.8 GHz, a power dissipation of 6.26 mW without power-configuration and a trans-impedance gain of 52.1 dBg2, a 3-dB bandwidth of 8.1 GHz, a power dis- sipation of 6.35 mW with power-configuration, respectively. The measured average input-referred noise-current spectral density is no more than 28 pA/√Hz. The chip area is only 0.08 x 0.08 mm2.

The design of a low-noise preamplifier for MRI

In this paper, a low-noise preamplifier for MRI is designed and studied. A noise matching network consisting of three elements is presented. To the single-stage AsGa-FET preamplifier working at 128 MHz, the measured gain through network analyzer (HP8712C) and noise figure through noise figure analyzer (8970B) are 25 and 0.43 dB, respectively.

A very low noise preamplifier for extremely low frequency magnetic antenna

Besides the electrode-pair antenna,the magnetic antenna is also used for the extremely low frequency （ELF） submarine communication.To receive the weak ELF signals,the structure of a small sized magnetic antenna determines its specific electrical characteristics.The ELF magnetic antenna shows high internal resistance, alternating-current impedance,and a resonance frequency near the operating bandwidth.In accordance with the electrical characteristics of ELF magnetic antenna,a low noise preamplifier and frequency compensation circuit were designed and realized.The preamplifier is a three-stage negative feedback circuit,which is composed of parallel JFET,common-emitter amplifier with a Darlington structure and a common-collector amplifier in push-pull connection.And a frequency compensation circuit is cascaded to compensate the characteristic in low frequency range.In the operating bandwidth f = 30-200 Hz,the circuit has a gain of 39.4 dB.The equivalent input noise is 1.97 nV/Hz^（1/2） and the frequency response keeps flat in operating bandwidth.The proposed preamplifier of the ELF magnetic antenna performs well in receiving ELF signals.

The final limitation of receiver terminal performance with remotely pumped preamplifiers

In this paper, the performance of receiver terminals with remotely pumped preamplifiers (RPPAs) is analyzed by numerical simulation and experiment. Both simulation and experiment show that there is an optimal RPPA location and optimal pump power according to the highest performance. The amplified spontaneous Raman scattering (ASRS) self-oscillation caused by Rayleigh backscattering (RBS) and the lump reflector in transmission line are the final performance limitation.

A 2.4GHz CMOS Monolithic Transceiver Front-End for IEEE 802.11b Wireless LAN Applications

A 2. 4GHz CMOS monolithic transceiver front-end for IEEE 802. llb wireless LAN applications is presented. The receiver and transmitter are both of superheterodyne structure for good system performance. The frontend consists of five blocks., low noise amplifier,down-converter, up-converter, pre-amplifier, and LO buffer. Their input/output impedance are all on-chip matched to 50 Ω except the down-converter which has open-drain outputs. The transceiver RF front-end has been implemented in a 0. 18μm CMOS process. When the LNA and the down-converter are directly connected, the measured noise figure is 5.2dB, the measured available power gain 12. 5dB, the input l dB compression point --18dBm,and the third-order input intercept point --7dBm. The receiver front-end draws 13.6mA currents from the 1.8V power supply. When the up-converter and pre-amplifier are directly connected, the measured noise figure is 12.4dB, the power gain is 23. 8dB, the output ldB compression point is 1.5dBm, and the third-order output intercept point is 16dBm. The transmitter consumes 27.6mA current from the 1.8V power supply.

A new probe for atmospheric electric field mill

A new probe for atmospheric electric field mill is introduced.It consists of three parts：signal acquisition circuit for atmospheric electric field,preamplifier circuit and phase sensitive detection circuit.The signal acquisition circuit adopts the double-stator structure to form differential input circuit,thus double-precision is obtained.Preamplifier circuit is made of current-to-voltage （I-V） conversion circuit,differential amplifier circtuit and secondary amplifying circuit.The polarity of electric field is obtained via phase sensitive detection circuit.Simulation results are obtained using Multisim,and the feasibility of the designed probe is verified.

Design of Amplifier Circuit for the HT-7 Tokamak Thomson Scattering System

Thomson scattering diagnostic is important for measuring electron temperature and density profiles. To improve the signal-to-noise ratio, a silicon avalanche photodiode （APD） with high quantum efficiency, high sensitivity, and high gain up to 100 was adopted to measure the Thomson scattering spectrum. A preamplifier, which has low noise, high bandwidth, and high sensitivity, was designed with suitable transimpedance. Using AD8367 as the post-amplifier, good performance of the APD readout electronics have been obtained. A discussion is presented on the performance of the amplifier using a laser diode to simulate the Thomson scattering light. The test results indicate that the designed circuit has a high amplifying factor and fast rising edge. So reduction of the integral gate of the CAMAC ADC converter can improve the signal-to-noise ratio.

A CMOS Microarray with On-Chip Decoder/Amplifier and Its Integration with a Bio-Nano-System

A fully integrated CMOS bio-chip is designed in a SMIC 0.18μm CMOS mixed signal process and successfully integrated with a novel bio-nano-system. The proposed circuit integrates an array of 4 × 4 （16 pixels） of 19μm × 19μm electrodes,a counter electrode, a current mode preamplifier circuit （CMPA） ,a digital decoding circuit,and control logics on a single chip, It provides a - 1.6- 1.6V range of assembly voltage,Sbit potential resolution, and a current gain of 39.8dB with supply voltage of 1.8V. The offset and noise are smaller than 5.9nA and 25.3pArms,respectively. Experimental resuits from on-chip selective assembly of 30nm poly （ethylene glycol） （PEG） coated magnetic nano-particles （MNPs） targeted at biosensor applications are included and discussed to verify the feasibility of the proposed circuits.

A compact neural recording interface based on silicon microelectrode

A prototype of hybrid neural recording interface has been developed for extracellular neural recording. It consists of a silicon-based plane microelectrode array and a CMOS low noise neural amplifier chip. The neural amplifier chip is designed and implemented in 0.18 μm N-well CMOS 1P6M technology. The area of the neural preamplifier is only 0.042 mm2 with a gain of 48.3 dB. The input equivalent noise is 4.73 btVrms within pass bands of 4 kHz. To avoid cable tethering for high dense mul- tichannel neural recording interface and make it compact, flip-chip bonding is used to integrate the preamplifier chip and the microelectrode together. The hybrid device measures 3 mm×5.5 mm×330μm, which is convenient for implant or in-vivo neu- ral recording. The hybrid device was testified in in-vivo experiment. Neural signals were recorded from hippocampus region of anesthetized Sprague Dawley rats successfully.