G. De Geronimo

Intensity noise reduction in a single-frequency ytterbium-codoped erbium laser

We report on intensity noise suppression in a diode-pumped, single-frequency erbium bulk-glass laser codoped with ytterbium. Using an optoelectronic feedback circuit, we acheived a 30-dB reduction of the relaxation oscillation peak, at 160-kHz frequency, to a relative intensity noise of 2114 dByHz. A useful output power of 15 mW at 1533-nm wavelength was obtained.

Criteria of choice of the front-end transistor for low-noise preamplification of detector signals at sub-microsecond shaping times for X- and γ-ray spectroscopy

Abstract We present an analysis of the electronic noise contributions which limit the resolution of X- and γ-ray spectrometers employing semiconductor detectors operating at room temperature and at signal processing times in the sub-microsecond range. The figures of merit of the front-end transistors, relevant to attain the highest resolution, are put in evidence. It is shown how the correlation between the gate and drain current noises in FETs plays a significant role in the equivalent noise charge of a charge preamplifier. Some state of the art devices, belonging to different technologies, JFET, MOSFET, MESFET and HFET, are examined.

A low‐noise wide‐band transimpedance amplifier for current noise spectra measurements

A low‐noise wide‐band transimpedance amplifier, designed to measure the spectral noise densities of currents in submicroampere range, is presented. The feedback transimpedance amplifier is designed to operate in a frequency range from 10–100 kHz, having an intrinsic noise as low as 3 fA/√Hz up to 1 kHz and less than 20 fA/√Hz at 100 kHz at room temperature, allowing the measurement of the shot noise of currents down to the 100‐pA range. The design criteria and experimental test on some devices are described.

Low frequency gate current noise in high electron mobility transistors: experimental analysis

An experimental investigation on the gate current noise in a pseudomorphic HEMT has been carried out. The measurements have been performed from 10 Hz to 100 kHz, at different bias conditions. It is shown that the noise spectral power density strongly depends on the biasing point and can be explained in terms of carrier trapping phenomena by means of packets of Lorentzian components.<<ETX>>

Application of 1/f noise measurements to the characterization of near-interface oxide traps in ULSI n-MOSFETs

1/f noise analysis is a promising method for estimating the density of near-interface states in small size metal-oxide semiconductor field effect transistor (MOSFET)s, as it does not require large-area devices and is not too sensitive to periphery effects. However, the applicability of the method to practical devices and the accuracy of the results obtained have not often been discussed in the literature. In this work, we report on the characterization of ultra-large-scale of integration (ULSI) n-MOSFETs with a heavy channel doping and a gate oxide fabricated with both a standard thermal oxide and an N2O-nitrided technology. We address the impact of channel quantization and mobility fluctuations on the 1/f results. The precision of the method is assessed by comparison with results obtained from conventional C–v measurements.

Integration of front-end electronics with GaAs pixel detectors: experimental and feasibility analysis

This work aims to study the feasibility of the integration, on the same chip, of GaAs pixel detectors and front-end electronics employing GaAs metal semiconductor FETs (MESFETs) or high electron mobility transistors (HEMTs). The interest of fully integrated GaAs systems lies in X and /spl gamma/-ray spectroscopy and imaging for scientific, industrial, and medical applications. The system design criteria and the prediction of the performance have been derived on the basis of recent experimental results on semi-insulating GaAs pixel detectors. Measurements of the relevant parameters of GaAs FETs suitable for the stringent requirements of a spectroscopy-grade front-end amplifier are analyzed. It is shown that an optimized GaAs integrated system can reach an electronic noise level below 100 electrons rms (<1 keV FWHM) even at room temperature. Some open problems regarding the detector-electronics integration are highlighted and discussed.

HEMT based integrated charge preamplifier first results

Abstract The new high luminosity accelerators and the objectives of the related high energy physics experiments pose severe requirements to both detectors and readout electronics [1,2]. A new generation of high speed front end electronics and signal processors has to be developed. In this perspective, we are presenting here an integrated charge preamplifier fully based on high electron mobility transistors (HEMT), mainly intended for semiconductor vertex detectors.

In view of low-noise and low-power GaAs front-ends

Abstract The use of GaAs in front-end electronics for radiation detection systems has been widely investigated by many authors and several prototypes of GaAs front-ends have been proposed. This work is a review and deepening of the criteria for the design of a low noise and low-power GaAs front-end. Remarks on the choice of the optimum bias point and gate width of the input transistor and on the choice of the shaping are discussed. A comparison of several GaAs FETs in terms of low-frequency noise and achievable resolution is also shown.

FRONT-END ELECTRONICS FOR A LARGE-AREA SILICON DETECTOR TELESCOPE

Abstract A large-area monolithic silicon detector telescope for particle identification has recently been realized. Due to the high capacitance (40 nF ) of the Δ E stage, commercially available charge preamplifiers cannot be used. We report on the design and characterization of a charge preamplifier suitably developed for the Δ E stage.

A low-power GaAs MESFET charge preamplifier

A low-power, high speed and high resolution preamplification and filtering stage, based on GaAs MESFETs has been designed, produced and tested. With a total power dissipation of 2mW and with a shaping time of 20ns, it is characterized by an Equivalent Noise Charge (ENC) below 180 electrons rms with a 1.25pF detector capacitance and by an ENC below 600 electrons rms with a 5.15pF detector capacitance.