Equivalent Input Noise Research Articles

High-Gm differential regulated cascode transimpedance amplifier

A differential cross-coupled regulated cascode(RGC)transimpedance amplifier(TIA)is proposed. The theory of multi-stage common-source (CS) configuration as an auxiliary amplifier to enhance the bandwidth and output impedance of RGC topology is analyzed. Additionally, negative Miller capacitance and shunt active inductor compensation are exploited to further expand the bandwidth. The proposed RGC TIA is simulated based on UMC 0.18 µm standard CMOS process. The simulation results demonstrate that the proposed TIA has a high transimpedance of 60.5 dBΩ, and a -3 dB bandwidth of 5.4 GHz is achieved for 0.5 pF input capacitance. The average equivalent input noise current spectral density is about 20 pA/Hz1/2 in the interested frequency, and the TIA consumes 20 mW DC power under 1.8 V supply voltage. The voltage swing is 460 mVpp, and the saturation input current is 500 µA.

Modular Printed Circuit Boards for Broadband Characterization of Nanoelectronic Quantum Devices

We report on the development of a modular system of high-frequency printed circuit boards (PCBs) for electrical low-noise characterization of multigate quantum devices. The whole measurement setup comprises PCBs operating from room temperature to a few kelvins, and custom software to control the broadband electronics held at cryogenic and room temperature. The PCBs coupling scheme and the custom tailoring of the user panel make our platform particularly flexible. At the cryogenic stage, one board hosts the electronics for readout. It consists in a custom complementary metal–oxide–semiconductor circuit for the current sensing. It is composed by a multiplexer for a digital selection of the device under test among up to four samples, connected to a cryogenic transimpedance amplifier with two possible gains, the maximum bandwidth of 250 kHz and the minimum equivalent input noise of 10 fA/ $\sqrt {\mathrm{Hz}}$ . Such board is coupled to the PCB sample holder, where 14 low-frequency input lines bias the devices and control the gates. Four additional high-frequency input paths with a bandwidth of 1 GHz and an isolation lower than −40 dB at 3 GHz have been implemented to apply a few millivolt pulses with a minimum duration of 1 ns. The PCBs assemblage and the cryogenic electronics are electrically characterized at 4.2 K and later used to perform quantum transport spectroscopy and single-charge dynamics readout at a few microsecond scales in two silicon nanoscaled field-effect transistors.

Non-ideal effects of MOS capacitor in a switched capacitor waveform recorder ASIC**Supported by National Natural Science Foundation of China (11375100), Strategic Pioneer Program on Space Sciences, Chinese Academy of Sciences (XDA04060606-06) and State Key Laboratory of Particle Detection and Electronics

SCAs (Switched Capacitor Arrays) have a wide range of uses, especially in high energy physics, nuclear science and astrophysics experiments. This paper presents a method of using a MOS capacitor as a sampling capacitor to gain larger capacitance with small capacitor area in SCA design. It studies the non-ideal effects of the MOS capacitor and comes up with ways to reduce these adverse effects. A prototype SCA ASIC which uses a MOS capacitor to store the samples has been designed and tested to verify this method. The SCA integrates 32 channels and each has 64 cells and a readout amplifier. The stored voltage is converted to a pair of differential currents (±4 mA max) and multiplexed to the output. All the functionalities have been verified. The power consumption is less than 2 mW/ch. The INL of all the cells in one channel are better than 0.39%. The equivalent input noise of the SCA has been tested to be 2.2 mV with 625 kHz full-scale sine wave as input, sampling at 40 MSPS (Mega-samples per Second) and reading out at 5 MHz. The effective resolution is 8.8 bits considering 1 V dynamic range. The maximum sampling rate reaches up to 50 MSPS and readout rate of 15 MHz to keep noise smaller than 2.5 mV. The test results validate the feasibility of the MOS capacitor.

Development of low-noise high-speed analog ASIC for X-ray CCD cameras and wide-band X-ray imaging sensors

We report on the development and performance evaluation of the mixed-signal Application Specific Integrated Circuit (ASIC) developed for the signal processing of onboard X-ray CCD cameras and various types of X-ray imaging sensors in astrophysics. The quick and low-noise readout is essential for the pile-up free imaging spectroscopy with a future X-ray telescope. Our goal is the readout noise of 5e−r.m.s. at the pixel rate of 1Mpix/s that is about 10times faster than those of the currently working detectors. We successfully developed a low-noise ASIC as the front-end electronics of the Soft X-ray Imager onboard Hitomi that was launched on February 17, 2016. However, it has two analog-to-digital converters per chain due to the limited processing speed and hence we need to correct the difference of gain to obtain the X-ray spectra. Furthermore, its input equivalent noise performance is not satisfactory (>100μV) at the pixel rate higher than 500kpix/s. Then we upgrade the design of the ASIC with the fourth-order ΔΣ modulators to enhance its inherent noise-shaping performance. Its performance is measured using pseudo CCD signals with variable processing speed. Although its input equivalent noise is comparable with the conventional one, the integrated non-linearity (0.1%) improves to about the half of that of the conventional one. The radiation tolerance is also measured with regard to the total ionizing dose effect and the single event latch-up using protons and Xenon, respectively. The former experiment shows that all of the performances does not change after imposing the dose corresponding to 590years in a low earth orbit. We also put the upper limit on the frequency of the latch-up to be once per 48years.

An Optimized Air-Core Coil Sensor with a Magnetic Flux Compensation Structure Suitable to the Helicopter TEM System.

The air-core coil sensor (ACS) is widely used as a transducer to measure the variation in magnetic fields of a helicopter transient electromagnetic (TEM) system. A high periodic emitting current induces the magnetic field signal of the underground medium. However, such current also generates a high primary field signal that can affect the received signal of the ACS and even damage the receiver. To increase the dynamic range of the received signal and to protect the receiver when emitting current rises/falls, the combination of ACS with magnetic flux compensation structure (bucking coil) is necessary. Moreover, the optimized ACS, which is composed of an air-core coil and a differential pre-amplifier circuit, must be investigated to meet the requirements of the helicopter TEM system suited to rapid surveying for shallow buried metal mine in rough topography. Accordingly, two ACSs are fabricated in this study, and their performance is verified and compared inside a magnetic shielding room. Using the designed ACSs, field experiments are conducted in Baoqing County. The field experimental data show that the primary field response can be compensated when the bucking coil is placed at an appropriate point in the range of allowed shift distance beyond the center of the transmitting coil and that the damage to the receiver induced by the over-statured signal can be solved. In conclusion, a more suitable ACS is adopted and is shown to have better performance, with a mass of 2.5 kg, resultant effective area of 11.6 m2 (i.e., diameter of 0.496 m), 3 dB bandwidth of 66 kHz, signal-to-noise ratio of 4 (i.e., varying magnetic field strength of 0.2 nT/s), and normalized equivalent input noise of 3.62 nV/m2.

Efficient noiseless linear amplification for light fields with larger amplitudes.

We suggest and investigate a scheme for non-deterministic noiseless linear amplification of coherent states using successive photon addition, (â(†))(2), where â(†) is the photon creation operator. We compare it with a previous proposal using the photon addition-then-subtraction, ââ(†), where â is the photon annihilation operator, that works as an appropriate amplifier only for weak light fields. We show that when the amplitude of a coherent state is |α| ≳ 0.91, the (â(†))(2) operation serves as a more efficient amplifier compared to the ââ(†) operation in terms of equivalent input noise. Using ââ(†) and (â(†))(2) as basic building blocks, we compare combinatorial amplifications of coherent states using (ââ(†))(2), â(†4), ââ(†)â(†2), and â(†2)ââ(†), and show that (ââ(†))(2), â(†2)ââ(†), and â(†4) exhibit strongest noiseless properties for |α| ≲ 0.51, 0.51 ≲ |α| ≲ 1.05, and |α| ≳ 1.05, respectively. We further show that the (â(†))(2) operation can be useful for amplifying superpositions of the coherent states. In contrast to previous studies, our work provides efficient schemes to implement a noiseless amplifier for light fields with medium and large amplitudes.

Editorial: Using Noise to Characterize Vision.

Editorial: Using Noise to Characterize Vision.

Investigation and Optimization of the Performance of an Air-Coil Sensor with a Differential Structure Suited to Helicopter TEM Exploration.

An air-coil sensor (ACS) is a type of induction magnetometer used as a transducer to measure the variations of a magnetic field. This device is widely applied in helicopter transient electromagnetic method (TEM) exploration. Most helicopter TEM explorations generate common-mode noise and require extreme ACS specifications, both of which inevitably challenge geophysical explorations. This study proposes a differential air-core coil combined with a differential pre-amplifier to reduce the common-mode noise induced in exploration surveys. To satisfy the stringent performance requirements, including the geometric parameters and electrical specifications, the physical calculations in theory and the equivalent schematic of an ACS with noise location are investigated, respectively. The theory calculation and experimental result for the optimized ACS are then compared on the basis of a differential structure. Correspondingly, an ACS is constructed with a mass, resultant effective area, 3 dB bandwidth, signal-to-noise ratio, and normalized equivalent input noise of 2.5 kg, 5.5 m2 (diameter is 0.5 m), 71 kHz, 20 (the varying magnetic field strength is 1 nT/s), and 5.43 nV/m2, respectively. These data are superior to those of the traditional induction sensor 3D-3. Finally, a field experiment is performed with a fabricated sensor to show a valid measurement of the time-varying magnetic field of a helicopter TEM system based on the designed ACS.

Over-the-Counter Hearing Aids: A Lost Decade for Change.

Background. Hearing aids sold directly to consumers in retail stores or through the internet, without individual prescription by audiological professionals, are termed over-the-counter (OTC) devices. This study aimed to determine whether there was any change in the electroacoustic characteristics of OTC devices compared to research carried out a decade earlier. The previous results indicated that most OTC devices were low-frequency-emphasis devices and were unsuitable for elderly people with presbycusis, who were likely to be the major consumers of these products. Methods. Ten OTC devices were selected and their electroacoustic performance was measured. Appropriate clients for the OTC devices were derived, using four linear prescription formulae, and OTC suitability for elderly persons with presbycusis was investigated. Results. OTC electroacoustic characteristics were similar to those in the earlier study. Most OTC devices were not acoustically appropriate for potential consumers with presbycusis. Although several of the devices could match prescriptive targets for individuals with presbycusis, their poor electroacoustic performance—including ineffective volume control function, high equivalent input noise, and irregular frequency response—may override their potential benefit. Conclusion. The low-cost OTC devices were generally not suitable for the main consumers of these products, and there has been little improvement in the appropriateness of these devices over the past decade.

Ultra‐low‐noise large‐bandwidth transimpedance amplifier

SummaryEquivalent input current noise and bandwidth are the most relevant parameters qualifying a low‐noise transimpedance amplifier. In the conventional topology consisting of an operational amplifier in a shunt‐shunt configuration, the equivalent input noise decreases as the feedback resistor (RF), which also sets the gain, increases. Unfortunately, as RF increases above a few MΩ, as it is required for obtaining high sensitivity, the bandwidth of the system is set by the parasitic capacitance of RF and reduces as RF increases. In this paper, we propose a new topology that allows overcoming this limitation by employing a large‐bandwidth voltage amplifier together with a proper modified feedback network for compensating the effect of the parasitic capacitance of the feedback resistance. We experimentally demonstrate, on a prototype circuit, that the proposed approach allows to obtain a bandwidth in excess of 100 kHz and an equivalent input noise of about 4 fA/ , corresponding to the current noise of the 1 GΩ resistor that is part of the feedback network. The new approach allows obtaining larger bandwidth with respect to those obtained in previously proposed configurations with comparable background noise. Copyright © 2014 John Wiley & Sons, Ltd.

A low offset chopper amplifier with three-stage nested Miller configuration

A low offset, low noise chopper amplifier for sensor system application is presented. Low 1/f noise is achieved by employing chopper technique, and low offset is achieved by employing residual offset suppression circuit. The open-loop gain is extended using three-stage nested Miller configuration. The chip was implemented in 0.5 μm 2P3M CMOS process. The amplifier is featured by an open-loop gain of 135 dB and a GBW of 3 MHz. The measured offset voltage is 3 μV, and the equivalent input noise power spectrum density at 1 Hz is 96 nV / \(\sqrt {Hz} \).

144 Channel measurement IC for CdZnTe sensors with energy and time resolution

A 144 channel measurement IC for CdZnTe detectors, used for PET, is presented. Each channel consists of a charge sensitive amplifier, a fast and a slow shaper, a peak sampler for the energy acquisition and an event detector based on a time to digital converter to generate an accurate time stamp for each event. The channels are multiplexed to a fast pipeline ADC on demand. Measurement results for the ASIC showed a noise equivalent input charge of 800e−rms and a time resolution of 737psrms. Evaluation results with a CdZnTe detector yielded an energy resolution of 4.4% full width half maximum at 662keV with a 137Cs radiation source. The IC is implemented on a 180nm CMOS process with a total chip size of 100mm2.

EVALUATION OF THE ULTRASONIC PREAMPLIFIER NOISE VOLTAGE DENSITY

Analysis of the noise voltage density evaluation procedures of the ultrasonic preamplifier is presented. Ultrasonic testing is demanding low noise reception channel. Techniques and equipment for ultrasonic preamplifier's noise performance evaluation are suggested. Equipment used and measurement technologies applied are described. One of the techniques suggested allows estimating the preamplifier noise with only impedance measurement results available. Sine wave correlation technique was used in the impedance measurement procedure. Another technique, not demanding the spectrum analyzer, was suggested, which uses the analog-to-digital converter (ADC) sampling and the Fourier transform to obtain the noise spectral density. Experimental results for the measured complex gain and the equivalent input noise of the preamplifier are presented. Comparison with traditional noise estimation procedure, using the spectrum analyzer is given. Both direct measurement techniques (ADC record Fourier analysis based and spectrum analyzer) indicated good match. Noise whiteness was estimated: in a region of operation frequencies, 5–7 MHz, noise can be considered as white.

Low-Noise Front-End Receiver Dedicated to Biomedical Devices: NIRS Acquisition System

This paper concerns the design and the implementation of a fully integrated front-end intended to Near-Infrared Spectroscopy System (NIRS) acquisition system. A low-noise transimpedance amplification (TIA) circuit followed by adjustable cut-off frequency and a low-pass filter (LPF) was implemented in order to decrease noise circuit of NIRS detectors. For TIA, a single ended common source, common gate input stage based on a cascode structure is used to get a higher gain-bandwidth closed-loop transimpedance amplifier. To enhance the circuit noise performance, a single feedback transistor technique is used, compared to passive feedback, to achieved high quality data from NIRS acquisition channel. The proposed LPF combines two control methods to adjust the low cut-off frequency. Simulation results show a TIA gain of 104.2 dBΩ, ?3dB bandwidth of 19 MHz and an equivalent input noise current spectral density of 446 fA/√Hz. LPF filter exhibits a relatively constant noise 201nV/√HzQUOTE√Hz from 0 Hz to 700 KHz and linearity performance over its entire tuning range. The proposed front-end of NIRS preamplifier is implemented using 0.18 μm CMOS technology.

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 μVrms within pass bands of 4 kHz. To avoid cable tethering for high dense multichannel 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×330 μm, which is convenient for implant or in-vivo neural recording. The hybrid device was testified in in-vivo experiment. Neural signals were recorded from hippocampus region of anesthetized Sprague Dawley rats successfully.

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 and the frequency response keeps flat in operating bandwidth. The proposed preamplifier of the ELF magnetic antenna performs well in receiving ELF signals.

GASTONE64: A new front-end ASIC for the cylindrical GEM Inner Tracker of KLOE-2 experiment at [formula omitted

GASTONE64 (Gem Amplifier Shaper Tracking ON Events) is a novel 64-channel mixed analog-digital ASIC developed to readout the cylindrical GEM inner tracking detector of the KLOE-2 apparatus at the e+e−DAΦNE collider. It has been designed in the CMOS 0.35μm technology and each analog channel is made of preamplifier, shaper and discriminator. The expected input charge ranges between few fC up to 40fC, the charge sensitivity is 16mV/fC while the equivalent input noise charge (ENC) is 800e−+40e−/pF. The discriminated signals are read-out using a 100MBit/s LVDS serial data link. The power consumption is about 6mW/channel.

A > 4 MGy radiation tolerant 8 THzOhm transimpedance amplifier with 50 dB dynamic range

A 130 nm Transimpedance Amplifier has been developed with a 255 MHz bandwidth, 90 dBΩ transimpedance gain and a dynamic input range of 1:325 or 50 dB for a photo-diode capacitance of 0.75 pF. The equivalent integrated input noise is 160 nA @ 25°C. The gain of the voltage amplifier, used in the transimpedance amplifier (TIA), degrades less than 3% over a temperature range from -40 °C up to 125 °C. The TIA and attenuator exhibit a radiation tolerance larger than 4 MGy, as evidenced by radiation assessment.

Signal Detection Technology for Giant Magnetoresistance Sensors

Presently, many attentions have been paid on low-noise pre-amplifier circuits and steady signal processing methods, but seldom on the combination of two technologies. In this paper, a small size low noise pre-amplifier circuit with 110dB Common Mode Rejection Ratio（CMRR）has been developed for giant magnetoresistance sensors(GMR) and its equivalent input noise voltage density is about . In addition, we proposed a new signal processing method for the sensors. In the method, we defined the quotient between the complex multiplex computation times and the output data num as a new figure of merit to evaluate that algorithm efficiency in signal detection, and name that quotient the computation times -to- output data num ratio (CTOR). Simulation results showed that the new method realized better parameters evaluation precision and higher efficiency than Modified Rife method, could be implemented easily in embedded systems.

Low-Noise Low-Delay Digital Signal Processor for Resonant Micro Optic Gyro

A low-noise low-delay digital signal processor is constructed on a single field-programmable gate array. An equivalent input noise as low as 3.752 nV/√Hz is demonstrated for the digital signal processor, which can detect an equivalent Sagnac effect of 0.003°/s in a resonant micro optic gyro (RMOG) with a 2.5-cm diameter ring resonator. With the processing time reduced from hundreds of seconds to 1.1 μs , this processor significantly increases the loop gain of the feedback loop and reduces the reciprocal noise in the RMOG. Owing to the fast speed of this processor, the lock-in frequency accuracy is reduced to 0.78 Hz (1σ), which is equivalent to a rotation rate of 0.004°/s. Relationship between this digitalized RMOG output signal and angular rate is obtained from ±0.25°/s to ±400°/s. The standard deviation of the residuals between RMOG output results and linear fit curve is 0.0236°/s.