Equivalent Input Noise Research Articles

The UmboMic: a PVDF cantilever microphone *

Objective. We present the ‘UmboMic,’ a prototype piezoelectric cantilever microphone designed for future use with totally-implantable cochlear implants. Methods. The UmboMic sensor is made from polyvinylidene difluoride (PVDF) because of its low Young’s modulus and biocompatibility. The sensor is designed to fit in the middle ear and measure the motion of the underside of the eardrum at the umbo. To maximize its performance, we developed a low noise charge amplifier in tandem with the UmboMic sensor. This paper presents the performance of the UmboMic sensor and amplifier in fresh cadaveric human temporal bones. Results. When tested in human temporal bones, the UmboMic apparatus achieves an equivalent input noise of 32.3 dB SPL over the frequency range 100 Hz–7 kHz, good linearity, and a flat frequency response to within 10 dB from about 100 Hz–6 kHz. Conclusion. These results demonstrate the feasibility of a PVDF-based microphone when paired with a low-noise amplifier. The reported UmboMic apparatus is comparable in performance to a conventional hearing aid microphone. Significance. The proof-of-concept UmboMic apparatus is a promising step towards creating a totally-implantable cochlear implant. A completely internal system would enhance the quality of life of cochlear implant users.

Design of a charge-sensitive amplifier for MEMS piezoelectric hydrophone

Hydrophone is an important part of sonar system and convert acoustic signal into electrical signal. However, the electrical signal generated by the hydrophone is relatively weak and cannot be directly used for underwater detection and communication. Therefore, it is necessary to preprocess the generated electrical signal. In this paper, a switched capacitor charge-sensitive amplifier for MEMS piezoelectric hydrophone is designed. In the structure, two single-channel charge amplifiers are used for time-division multiplexing. The noise sampling and charge amplification are performed separately in the same half cycle to achieve the effect of alternating output, thereby increasing the sampling rate and solving the problem of discontinuous output of the switched capacitor circuit. In the circuit design, virtual switch and two-phase non-overlapping clock are adopted to reduce the error caused by charge injection and clock feedthrough effect of CMOS switch. What’s more, the correlated double sampling technique is used to reduce the offset and low frequency noise of the circuit. The gain of the charge-sensitive amplifier designed in this study is 26 dB, the bandwidth is 0.8Hz∼17.6kHz, the equivalent input noise power spectral density is 115.6 nV/Hz at 0.1Hz, and the charge sensitivity is 2 mV / pC. The fitting line between the input charge and the amplitude of the output curve is similar to the theory. The simulation results show that the charge-sensitive amplifier proposed in this study meets the design requirements of the MEMS piezoelectric hydrophone readout circuit.

An Implantable Piezofilm Middle Ear Microphone: Performance in Human Cadaveric Temporal Bones.

One of the major reasons that totally implantable cochlear microphones are not readily available is the lack of good implantable microphones. An implantable microphone has the potential to provide a range of benefits over external microphones for cochlear implant users including the filtering ability of the outer ear, cosmetics, and usability in all situations. This paper presents results from experiments in human cadaveric ears of a piezofilm microphone concept under development as a possible component of a future implantable microphone system for use with cochlear implants. This microphone is referred to here as a drum microphone (DrumMic) that senses the robust and predictable motion of the umbo, the tip of the malleus. The performance was measured by five DrumMics inserted in four different human cadaveric temporal bones. Sensitivity, linearity, bandwidth, and equivalent input noise were measured during these experiments using a sound stimulus and measurement setup. The sensitivity of the DrumMics was found to be tightly clustered across different microphones and ears despite differences in umbo and middle ear anatomy. The DrumMics were shown to behave linearly across a large dynamic range (46dB SPL to 100dB SPL) across a wide bandwidth (100Hz to 8kHz). The equivalent input noise (over a bandwidth of 0.1-10kHz) of the DrumMic and amplifier referenced to the ear canal was measured to be about 54dB SPL in the temporal bone experiment and estimated to be 46dB SPL after accounting for the pressure gain of the outer ear. The results demonstrate that the DrumMic behaves robustly across ears and fabrication. The equivalent input noise performance (related to the lowest level of sound measurable) was shown to approach that of commercial hearing aid microphones. To advance this demonstration of the DrumMic concept to a future prototype implantable in humans, work on encapsulation, biocompatibility, and connectorization will be required.

Contribution of internal noise and calculation efficiency to face discrimination deficits in older adults

Classification images (CIs) measured in a face discrimination task differ significantly between older and younger observers. These age differences are consistent with the hypothesis that older adults sample diagnostic face information less efficiently, or have higher levels of internal noise, compared to younger adults. The current experiments assessed the relative contributions of efficiency and internal noise to age differences in face discrimination using the external noise masking and double-pass response consistency paradigms. Experiment 1 measured discrimination thresholds for faces embedded in several levels of static white noise, and the resulting threshold-vs.-noise curves were used to estimate calculation efficiency and equivalent input noise: older observers had lower efficiency and higher equivalent input noise than younger observers. Experiment 2 presented observers with two identical sequences of faces embedded in static white noise to measure the association between response accuracy and response consistency and estimate the internal:external (i/e) noise ratio for each observer. We found that i/e noise ratios did not differ significantly between groups. These results suggest that age differences in face discrimination are due to differences in calculation efficiency and additive internal noise, but not to age differences in multiplicative internal noise.

Noise Spectroscopy Analysis of Ion Behavior in Liquid Gate‐All‐Around Silicon Nanowire Field‐Effect Transistor Biosensors

AbstractThe transport and noise properties of fabricated, high‐performance, gate‐all‐around silicon liquid‐gated nanowire field‐effect transistor devices are investigated in different concentrations of MgCl2 solutions. The critical concentration of MgCl2 solution for charge inversion at the solid‐liquid interface is verified using noise spectroscopy and confirmed using the capacitance‐voltage measurement technique. In this study, it is found that the Hooge parameter (αH) and the equivalent input noise (SU) can effectively reflect the ion behavior on the surface of the nanowire. Moreover, the noise curves for αH and SU indicate two turning points at concentrations of 10−4 and 10−1 m for a peak and a valley, respectively. The noise transformation is related to the behavior of ions near the solid‐liquid interface in solutions with different MgCl2 concentrations is revealed. The results show that noise spectroscopy is a powerful method for monitoring charge dynamic processes in the research field of biosensors.

A 17 GHz inductorless low‐pass filter based on a quasi‐Sallen–Key approach

SummaryIn this paper, an evolution of the Sallen–Key biquad architecture is presented, suitable for applications at very high frequency. The pole of the buffer amplifier is exploited as one of the poles of the biquad, therefore overcoming the constraints it poses on the maximum resonance frequency that can be achieved. This allows designing low‐pass filters with cutoff frequencies above 10 GHz without using bulky inductors and with good linearity performance provided by the use of feedback. This approach has been exploited to design a biquad in a commercial SiGe BiCMOS technology with maximum of about 320 GHz. The biquad has been designed to provide a resonance frequency of 12 GHz and a quality factor Q of 1.9; postlayout simulations show a cutoff frequency in excess of 17 GHz, 15.75 mW of power consumption, an equivalent input noise below 1 Vrms, and −52 dB of total harmonic distortion (THD) for a 640 mVpp input signal, with a very limited area consumption.

A Low-Power DROIC With Extended-Counting ADC for Uncooled Infrared Silicon Diode Detectors

A low-power digital readout integrated circuit (DROIC) for silicon diode uncooled infrared focal plane arrays (IRFPAs) is presented. The DROIC adopts a 14-bit column-level extended-counting analog-to-digital converter (ADC) based on a cascade of a coarse continuous-time Σ-ADC and a fine single-slope ADC. While the weak detector signal is integrated, the coarse conversion is implemented by a feedback current-steering digital-to-analog converter (IDAC), which shortens the signal chain and reduces the bandwidth requirement for the op-amp, to reduce power consumption. Besides, the ramp signal of the fine conversion is generated locally by an additional column-level IDAC, which matches the coarse conversion IDAC to decrease the DNL. Also, a low-power non-uniformity calibration circuit is adopted to compensate the non-uniformity of the IRFPA and adjust the ADCfs input signal range. The DROIC with 1024 ×768 pixel array is fabricated in a 0.18μm CMOS process. The experimental results demonstrate the DROIC consumes 109mW. The noise is 1.7LSB and the equivalent input noise voltage of the column circuit is about 2.1μVrms. The INL and DNL are less than +6.1LSB/.4.4LSB and +0.40LSB/.0.38LSB, respectively.

Weak Capacitance Detection Circuit of Micro-Hemispherical Gyroscope Based on Common-Mode Feedback Fusion Modulation and Demodulation.

As an effective capacitance signal produced by a micro-hemisphere gyro is usually below the pF level, and the capacitance reading process is susceptible to parasitic capacitance and environmental noise, it is highly difficult to acquire an effective capacitance signal. Reducing and suppressing noise in the gyro capacitance detection circuit is a key means to improve the performance of detecting the weak capacitance generated by MEMS gyros. In this paper, we propose a novel capacitance detection circuit, where three different means are utilized to achieve noise reduction. Firstly, the input common-mode feedback is applied to the circuit to solve the input common-mode voltage drift caused by both parasitic capacitance and gain capacitance. Secondly, a low-noise, high-gain amplifier is used to reduce the equivalent input noise. Thirdly, the modulator-demodulator and filter are introduced to the proposed circuit to effectively mitigate the side effects of noise; thus, the accuracy of capacitance detection can be further improved. The experimental results show that with the input voltage of 6 V, the newly designed circuit produces an output dynamic range of 102 dB and the output voltage noise of 5.69 nV/√Hz, achieving a sensitivity of 12.53 V/pF.

Ultra-low-noise transimpedance amplifier in cryogenic STM for studying novel quantum states by measuring shot noise

An ultra-low-noise large-bandwidth transimpedance amplifier (TIA) for cryogenic scanning tunneling microscope (CryoSTM) is proposed. The TIA connected with the tip-sample component in CryoSTM is called as CryoSTM-TIA. Its transimpedance gain is as high as 1 GΩ, and its bandwidth is over 300 kHz, but its equivalent input noise current power spectral density is less than 4 (fA)2/Hz at 100 kHz. The low inherent noise for the CryoSTM-TIA is due to its special design: (1) its pre-amplifier is made of a pair of low-noise cryogenic high electron mobility transistors (HEMTs); (2) the noise generated by one HEMT is eliminated by a large capacitor; (3) the capacitance of the cable connected the gate of the other HEMT to the tip is minimized; (4) thermal noise sources, such as the feedback resistor, are placed in the cryogenic zone. The dc output voltage drift of the CryoSTM-TIA is very low, as 5 μV/°C. The apparatus can be used for measuring the scanning tunneling differential conductance spectra, especially the scanning tunneling shot noise spectra (STSNS) of quantum systems, even if the shot noise is very low. It provides a universal tool to study various novel quantum states by measuring STSNS, such as detecting the Majorana bound states.

A CMOS transimpedance amplifier with broad-band and high gain based on negative Miller capacitance

A CMOS transimpedance amplifier (TIA) with broad band and high gain based on negative Miller capacitance and capacitive degeneration has been proposed and designed. The theoretical analysis shows that by introducing negative Miller capacitance into the feedforward common gate (FCG) amplifier circuit, the bandwidth limitation caused by the internal parasitic capacitance can be reduced, and by cascading the capacitive degeneration-based common source (CS) amplifier as the gain stage, the amplifier gain can be improved simultaneously. The proposed TIA is designed and simulated in TSMC 65 nm CMOS process, The simulation results show that the −3 dB bandwidth of the amplifier circuit is 23.7 GHz, the transimpedance gain is 60.1 dBΩ, the average equivalent input noise current spectral density is less than 40.7 pA/√Hz, the power consumption is 4.8 mW, and the circuit layout area is 0.0027 mm2. In Comparison to the published TIA circuits, the bandwidth of the designed CMOS TIA is increased by 12.7 GHz, the gain is increased by 18.1 dBΩ and the circuit layout area becomes smaller. All the results demonstrate that the designed TIA can be used in the photoelectric detection circuit with broader bandwidth and higher gain.

Design of chopper operational amplifier for leakage current protector chip

Due to the low frequency and small amplitude of the input signal of the leakage current protection chip, an operational amplifier with low offset and low power consumption is designed by using the chopper stabilization technique and the dynamic element matching technique. Based on the TSMC 0.18um process, the spectre environment in cadence is used for design and simulation. The power supply voltage is 1.8V. The post simulation results show that under the TT corner, the average current of the operational amplifier is 139uA, the loop gain is 85.9dB, the phase margin is 68.01°, and the power supply rejection ratio(PSRR) is 101.62dB@50Hz, the common mode rejection ration(CMRR) is 104.52dB@50Hz, the equivalent input noise is 129.86nv/sqrt(Hz)@50Hz, and the value of equivalent input offset voltage is 8.2uV(mean).

Multi-photon-addition amplified coherent state

State [Formula: see text] and state [Formula: see text] are same to state [Formula: see text], which is called as multi-photon-addition amplified coherent state (MPAACS) by us. Here, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] are photon number operator, creation operator, coherent state, gain factor, and an integer, respectively. We study mathematical and physical properties for these MPAACSs, including normalization, photon component analysis, Wigner function, effective gain, quadrature squeezing, and equivalent input noise. Actually, the MPAACS, which contains more nonclassicality, is an amplified version of photon-added coherent state (PACS) introduced by Agarwal and Tara [Phys. Rev. A 43, 492 (1991)]. Our work provides theoretical references for implementing amplifiers for light fields.

On the Use of Supercapacitors for DC Blocking in Transformer-Coupled Voltage Amplifiers for Low-Frequency Noise Measurements

When performing low-frequency noise measurements on low-impedance electron devices, transformer coupling can be quite effective in reducing the contribution of the equivalent input noise voltage of the preamplifier to the background noise of the system. However, noise measurements on electron devices are usually performed with a biased device under test. A bridge configuration must be used to null the DC component at the input of the transformer. Unfortunately, using a bridge results in a complication of the set-up and degradation of the system’s sensitivity because of the noise introduced by the nulling arm. We propose an alternative approach for blocking the DC component that exploits the fact that supercapacitors with capacitances in excess of a few Farads are nowadays easily available. Actual measurement results in conventional and advanced measurement configurations are discussed that demonstrate the advantages of the approach we propose.

Low-noise large-bandwidth transimpedance amplifier for measuring scanning tunneling shot noise spectra in cryogenic STM and its applications

Shot noise is a powerful tool to study quantum systems. In this work, a design of transimpedance amplifier (TIA) for a cryogenic scanning tunneling microscope (CryoSTM) is proposed to meet the requirements of the shot noise measurements for quantum systems. In the TIA, the preamplifier is made of the low-noise low-power cryogenic high electron mobility transistors. With the high transimpedance gain of 1 GΩ, the bandwidth of the proposed TIA is larger than 300 kHz. In the CryoSTM, the TIA with the tip-sample component is called as CryoSTM-TIA. The bandwidth of the proposed CryoSTM-TIA is still larger than 300 kHz. Its equivalent input noise current power spectral density is less than 30(fA)2/Hz at 100 kHz. It is detailed, for quantum systems, by using the CryoSTM-TIA, how to measure scanning tunneling current spectra, scanning tunneling differential conductance spectra, and scanning tunneling noise current power spectra, in atomic scale, and then extract their scanning tunneling shot noise spectra. Thus, it is possible to study novel quantum phenomena in various quantum systems by measuring shot noise with the CryoSTM-TIA, such as the Andreev reflection in atomic scale, the Kondo effect in a single molecular magnet, and the existence of Majorana bound states, etc.

Design of MIRA, a low-noise pixelated ASIC for the readout of micro-channel plates

We present the design of the first prototype of MIRA (MIcro-channel plate Readout ASIC) that has been designed to read out Micro-Channel Plates (MCP), in particular for UV spectroscopy. MIRA will be able to detect the cloud of electrons generated by each photon interacting with the MCP, sustaining high local and global count rates to fully exploit the MCP intrinsic dynamic range with low dead time. The main rationale that guided the electronics design is the reduction of the input Equivalent Noise Charge (ENC) in order to allow operations with lower MCP gain, thus improving its lifetime, crucial aspect for long missions in space. MIRA features two selectable analog processing times, 133 ns or 280 ns (i.e. fast mode or slow mode), granting a count rate per pixel of 100 kcps. Moreover, it shows an Equivalent Noise Charge ENC . A spatial resolution of 35 μm and an operation with zero dead time, due to the readout, are targeted. The low noise, high count rate and high spatial resolution requirements are expected by keeping a compact pixel size (35 μm × 35 μm) for a total of 32 × 32 pixels in a 2 mm × 2 mm ASIC area. In this work, the ASIC design is described.

HEPS-BPIX3: a fine pitch pixel readout chip working in single photon counting mode for synchrotron radiation applications

HEPS-BPIX3 is a hybrid pixel detector readout chip for X-ray applications for the High Energy Photon Source (HEPS) in China. The readout chip contains an array of 88 × 88 pixels with a pixel size of 55 μm × 55 μm, working in single photon counting mode. Each pixel handles both polarities of positive and negative input charge signals and has a counting depth of 11 bits. Using a clock with a frequency up to 160 MHz, the chip can read out serially with zero dead time. Designed in a 130 nm CMOS technology, the chip has been measured and given the CSA charge gain of 17.6 mV/ke- for electron collection and 13 mV/ke- for hole collection, respectively. Bump-bonded detector modules with a 320-μm-thick silicon sensor were also tested. The test results showed an equivalent input noise of 156 e- and a counting rate up to 2.2 Mcps. Besides, an image using an X-ray tube was demonstrated and a frame rate of 1.8 kHz could be guaranteed. Measured characteristics present the normal functionality of the HEPS-BPIX3 chip and prove that the chip satisfies the HEPS requirements.

Low-Noise Balanced Photoreceiver With InP-on-Si Photodiodes and SiGe BiCMOS Transimpedance Amplifier

A photoreceiver consisting of indium phosphide (InP) balanced photodiodes (PD) on Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> waveguides and a transimpedance amplifier (TIA) fabricated in a silicon germanium (SiGe) BiCMOS process is demonstrated. The InP PDs, heterogeneously integrated on a silicon substrate, achieve external (internal) responsivities of 0.75 (0.9) A/W, bandwidths of 4 GHz, and common mode rejection ratios (CMRR) of greater than 40 dB when illuminated differentially. The TIA achieves 74 dBΩ of transimpedance gain with a 1 dB peak, a bandwidth of 3 GHz, and a low equivalent input noise current density of 7.2 pA/√{Hz} when loaded with a C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PD</sub> of 380 fF. The full photoreceiver achieves high conversion gain of more than 2 kV/W up through 2 GHz, and a low NEP of 8 pW/√{Hz} up through 1.6 GHz. The photoreceiver optical CMRR is measured to be 36 dB.

A Low Noise 28Gbaud/s Linear PAM4 Receiver Front-End for Optical Communication Applications in 0.13μm BiCMOS Technology

This paper presents a low noise 28 Gbaud/s linear receiver front-end for fourth-order pulse amplitude modulation (PAM4) signal applied in the field of optical communication. The designed receiver front-end includes a transimpedance amplifier(TIA), an automatic gain control (AGC) and a DC offset cancellation (DCOC) circuit. The pseudo-differential structure of the TIA is designed to achieve low noise. The resistance and capacitance degradation technology are introduced in the variable gain amplifier(VGA) and the equalizer(EQ) to improve linearity and optimize the bandwidth. In the AGC mode, the feedback loop controls the output amplitude to be a desired value within a large range of input current. The PAM4 optical receiver front-end achieves a maximum differential transimpedance gain of 76 dBΩ and -3dB bandwidth of 27 GHz. The equivalent input noise current density with the front-end circuit is . In 0.13µm BiCMOS technology, the PAM4 front-end chip consumes 200 mW with a 3.3V voltage supply.

Feasibility of Personal Sound Amplification Products in Patients With Moderate Hearing Loss: A Pilot Study.

ObjectivesThis study was conducted to investigate the electroacoustic characteristics of personal sound amplification products (PSAPs), to identify whether PSAPs provide adequate gain and output for three common hearing loss (HL) configurations, and to compare the benefits of a representative PSAP (RPSAP) and a conventional hearing aid (HA) for clinical hearing outcomes as a pilot study.MethodsThe study comprised three phases: electroacoustic analysis, simulated real-ear measurements (REMs), and clinical hearing experiments. Electroacoustic analysis and simulated REMs were performed for three basic PSAPs (BeethoSOL, EarJJang, and Geniesori2) and three high-end PSAPs (Hearing Able, Olive Smart Ear, and SoriIn) using the Aurical Hearing Instrument Test box with a 2-mL coupler. Four electroacoustic characteristics (maximum output sound pressure level at 90 dB SPL, frequency range, equivalent input noise, and total harmonic distortion) were investigated. By simulated REMs, appropriate levels of the six PSAPs for three common HL configurations (mild-to-moderate high-frequency HL, moderate to moderately severe sloping HL, and moderate flat HL) were determined. Clinical experiments compared the performance of RPSAP to HA, both of which were fitted by audiologists using REMs. Clinical experiments were administered using functional gain, a word recognition test, and the Korean version of the Hearing in Noise Test in six participants with bilateral moderate sensorineural HL.ResultsThe two high-end devices met all tolerances. One basic and two high-end PSAPs showed appropriate levels for three common HL configurations. In the clinical experiments, the RPSAP showed better performance than unaided, but slightly worse than HA under all test conditions.ConclusionCertain PSAPs met all specified tolerances for electroacoustic analysis and approximated prescriptive targets in well-controlled laboratory conditions. The pilot clinical experiments explored the possibility that the RPSAP could serve as a hearing assistive device for patients with moderate HL.

Variance-dependent neural activity in an unvoluntary averaging task.

Ensemble statistics of a visual scene can be estimated to provide a gist of the scene without detailed analysis of all individual items. The simplest and most widely studied ensemble statistic is mean estimation, which requires averaging an ensemble of elements. Averaging is useful to estimate the mean of an ensemble and discard the variance. The source of variance can be external (i.e., variance across the physical elements) or internal (i.e., imprecisions in the estimates of the elements by the visual system). The equivalent noise paradigm is often used to measure the impact of the internal variance (i.e., the equivalent input noise). This paradigm relies on the assumption that the averaging process is equally effective independently of the main source of variance, internal or external, so any difference between the processing when the main source of variance is internal or external must be assumed not to affect the averaging efficiency. The current fMRI study compared the neural activity when the main variance is caused by the stimulus (i.e., high variance) and when it is caused by imprecisions in the estimates of the elements by the visual system (i.e., low variance). The results showed that the right superior frontal and left middle frontal gyri can be significantly more activated when the variance in the orientation of the Gabors was high than when it was low. Consequently, the use of the equivalent noise paradigm requires the assumption that such additional neural activity in high variance does not affect the averaging efficiency.