scholarly journals A High Value, Linear and Tunable CMOS Pseudo-Resistor for Biomedical Applications

2019 ◽  
Vol 28 (06) ◽  
pp. 1950096 ◽  
Author(s):  
R. Nagulapalli ◽  
K. Hayatleh ◽  
S. Barker ◽  
P. Georgiou ◽  
F. J. Lidgey
Keyword(s):  
Biomedical Applications ◽  
Room Temperature ◽  
Cutoff Frequency ◽  
Na Current ◽  
Current Generator ◽  
Temperature Drift ◽  
Low Pass ◽  
Low Distortion ◽  
High Pass ◽  
Very High

A subthreshold MOS-based pseudo-resistor featuring a very high value and ultra-low distortion is proposed. A bandpass neural amplifier with a very low high-pass cutoff frequency is designed, to demonstrate the linearity of the proposed resistor. A BJT less CTAT current generator has been introduced to minimize the temperature drift of the resistor and make tuning easier. The standalone resistor has achieved 0.5% better linearity and a 12% improved temperature coefficient over the existing architectures. A neural amplifier has been designed with the proposed resistor as a feedback element. It demonstrated 31[Formula: see text]dB mid-band gain and a low-pass cutoff frequency of 0.85[Formula: see text]Hz. The circuit operates from a 1[Formula: see text]V supply and draws 950[Formula: see text]nA current at room temperature.

Some Effects of Noise on the Speaking Behavior of Stutterers

1974 ◽  
Vol 17 (4) ◽  
pp. 714-723 ◽  
Author(s):  
Edward G. Conture
Keyword(s):  
Frequency Spectrum ◽  
Broad Band ◽  
Cutoff Frequency ◽  
Reading Rate ◽  
Read Aloud ◽  
Noise Condition ◽  
Low Pass ◽  
Frequency Reading ◽  
High Pass ◽  
Different Levels

The purpose of the present research was to determine the influence of the loudness and spectrum of noise stimuli on stuttering frequency, reading rate, and vocal level. During each of six noise conditions and one non-noise condition, nine stutterers continuously read aloud prose passages during four successive five-minute periods. Low-pass (500-Hz cutoff frequency), high-pass (500-Hz cutoff frequency), and broad-band noise, psychophysically equated for loudness at two different levels, was presented during the third period of the six noise conditions. Stuttering frequency, reading rate, and vocal level were measured for the second and third periods of all conditions. The stutterers increased their vocal level while decreasing their stuttering frequency as a result of the loudness rather than the frequency spectrum of the noise. Reading rate was not significantly influenced by changes in the loudness or frequency spectrum of the noise. These results do not support the findings of others that low-pass noise decreases stuttering more than does high-pass noise.

scholarly journals Active Filter Analysis on Designing Electronic Stethoscope

2019 ◽  
Vol 19 (2) ◽  
pp. 51
Author(s):  
Prihatin Oktivasari ◽  
Riandini Riandini ◽  
Rahmah A. Fitri ◽  
Sungguh I. Malaon
Keyword(s):  
Fourth Order ◽  
Heart Sound ◽  
Cutoff Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Electronic Stethoscope ◽  
Recorded Sound ◽  
Low Pass ◽  
High Pass

Early heart disease detection could be vital and some other diagnostic ways are being developed. In this paper, a lowcost tool for a diagnostic that analyzes the digitized heartbeat sound is given. This can be used to detect heart anomalies. The instrument shows the heart sound and also keeps a patient's long-term record for future use. The signal from the heart provides a lot of knowledge about the heart and offers an initial diagnosis recommendation. The electronic stethoscope uses the condenser microphone, preamplifier circuit, and filter circuit. The optimum filter is Butterworth with a fourth-order Sallen key low pass filter topology with a gain of 0.707 volts, -3.01 dB, and a fourth-order high pass filter with a gain of 0.782 volts, -2.137 dB. The frequency of the heart sound is about 20 Hz – 120 Hz in general. Therefore, the lower cutoff frequency of the filter is set to 20 Hz, while the higher cutoff frequency set to 120 Hz. The evaluation used to measure the performance of an electronic stethoscope is to compare with a conventional stethoscope, the recorded sound is the same.

Spectral Contributions to the Benefit From Spatial Separation of Speech and Noise

2002 ◽  
Vol 45 (6) ◽  
pp. 1297-1310 ◽  
Author(s):  
Judy R. Dubno ◽  
Jayne B. Ahlstrom ◽  
Amy R. Horwitz
Keyword(s):  
Older Adults ◽  
Hearing Loss ◽  
Cutoff Frequency ◽  
Spatial Separation ◽  
Normal Hearing ◽  
Noise Sources ◽  
Low Pass ◽  
The Difference ◽  
Interaural Level Differences ◽  
High Pass

Speech recognition in noise improves when speech and noise sources are separated in space. This benefit has two components whose effects are strongest in different frequency regions: (1) interaural level differences (e.g., head shadow), which are largest at higher frequencies, and (2) interaural time differences, which have their greatest contribution at lower frequencies. Binaural interactions enhance the separation of signals from noise through the use of these interaural differences. Here, the benefit attributable to spatial separation was measured as a function of the low- and high-pass cutoff frequency of speech and noise. Listeners were younger adults with normal hearing, older adults with normal hearing, and older adults with hearing loss. Binaural thresholds for narrowband noises were measured in quiet and in a speech-shaped masker as a function of masker low-pass cutoff frequency. Speech levels corresponding to 50% correct recognition of sentences from the Hearing in Noise Test (HINT) were measured in a 65-dB SPL speech-shaped noise. Thresholds for narrowband noises and for speech were measured with two loudspeaker configurations: (1) signals and speech-shaped noise at 0° azimuth (in front of the listener) and (2) signals at 0° azimuth and speech-shaped noise at 90° azimuth (at the listener's side). The criterion measure was spatial separation benefit, or the difference in thresholds for the two conditions. Benefit of spatial separation for unfiltered speech averaged 6.1 dB for younger listeners with normal hearing, 4.9 dB for older listeners with normal hearing, and 2.7 dB for older listeners with hearing loss. Benefit was differentially affected by low-pass and high-pass filtering, suggesting a trade-off of the contributions of higher frequency interaural level differences and lower frequency interaural timing cues. As expected, older listeners with hearing loss benefited little from the improved signal-to-noise ratios in the higher frequencies resulting from head shadow, but showed some benefit from lower frequency cues. Spatial benefit for older listeners with normal hearing was reduced relative to benefit for younger listeners. This result may be related to older listeners' elevated thresholds at frequencies above 6.0 kHz.

scholarly journals Ultrabright Au@Cu14 nanoclusters: 71.3% phosphorescence quantum yield in non-degassed solution at room temperature

2021 ◽  
Vol 7 (2) ◽  
pp. eabd2091
Author(s):  
Yongbo Song ◽  
Yingwei Li ◽  
Meng Zhou ◽  
Xuan Liu ◽  
Hao Li ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Biomedical Applications ◽  
Room Temperature ◽  
Organometallic Complexes ◽  
Metal Nanoclusters ◽  
Electron Dynamics ◽  
Electronic Engineering ◽  
Phosphorescence Quantum Yield ◽  
Phosphorescence Emission ◽  
Very High

The photoluminescence of metal nanoclusters is typically low, and phosphorescence emission is rare due to ultrafast free-electron dynamics and quenching by phonons. Here, we report an electronic engineering approach to achieving very high phosphorescence (quantum yield 71.3%) from a [Au@Cu14(SPhtBu)12(PPh(C2H4CN)2)6]+ nanocluster (abbreviated Au@Cu14) in non-degassed solution at room temperature. The structure of Au@Cu14 has a single-Au-atom kernel, which is encapsulated by a rigid Cu(I) complex cage. This core-shell structure leads to highly efficient singlet-to-triplet intersystem crossing and suppression of nonradiative energy loss. Unlike the phosphorescent organic materials and organometallic complexes—which require de-aerated conditions due to severe quenching by air (i.e., O2)—the phosphorescence from Au@Cu14 is much less sensitive to air, which is important for lighting and biomedical applications.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Trombone Transfer Functions: Comparison Between Frequency-Swept Sine Wave and Human Performer Input

2012 ◽  
Vol 37 (4) ◽  
pp. 447-454
Author(s):  
James W. Beauchamp
Keyword(s):  
Transfer Function ◽  
Transfer Functions ◽  
Cutoff Frequency ◽  
Sine Wave ◽  
Nonlinear Propagation ◽  
Linear Filter ◽  
Wave System ◽  
General Effect ◽  
Filter Characteristic ◽  
High Pass

Abstract Source/filter models have frequently been used to model sound production of the vocal apparatus and musical instruments. Beginning in 1968, in an effort to measure the transfer function (i.e., transmission response or filter characteristic) of a trombone while being played by expert musicians, sound pressure signals from the mouthpiece and the trombone bell output were recorded in an anechoic room and then subjected to harmonic spectrum analysis. Output/input ratios of the signals’ harmonic amplitudes plotted vs. harmonic frequency then became points on the trombone’s transfer function. The first such recordings were made on analog 1/4 inch stereo magnetic tape. In 2000 digital recordings of trombone mouthpiece and anechoic output signals were made that provide a more accurate measurement of the trombone filter characteristic. Results show that the filter is a high-pass type with a cutoff frequency around 1000 Hz. Whereas the characteristic below cutoff is quite stable, above cutoff it is extremely variable, depending on level. In addition, measurements made using a swept-sine-wave system in 1972 verified the high-pass behavior, but they also showed a series of resonances whose minima correspond to the harmonic frequencies which occur under performance conditions. For frequencies below cutoff the two types of measurements corresponded well, but above cutoff there was a considerable difference. The general effect is that output harmonics above cutoff are greater than would be expected from linear filter theory, and this effect becomes stronger as input pressure increases. In the 1990s and early 2000s this nonlinear effect was verified by theory and measurements which showed that nonlinear propagation takes place in the trombone, causing a wave steepening effect at high amplitudes, thus increasing the relative strengths of the upper harmonics.

scholarly journals 1.0 V-0.18 µm CMOS Tunable Low Pass Filters with 73 dB DR for On-Chip Sensing Acquisition Systems

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 563
Author(s):  
Jorge Pérez-Bailón ◽  
Belén Calvo ◽  
Nicolás Medrano
Keyword(s):  
Power Consumption ◽  
Dynamic Range ◽  
Low Voltage ◽  
Cutoff Frequency ◽  
Cmos Technology ◽  
Active Area ◽  
Current Steering ◽  
Low Pass ◽  
On Chip ◽  
Low Pass Filters

This paper presents a new approach based on the use of a Current Steering (CS) technique for the design of fully integrated Gm–C Low Pass Filters (LPF) with sub-Hz to kHz tunable cut-off frequencies and an enhanced power-area-dynamic range trade-off. The proposed approach has been experimentally validated by two different first-order single-ended LPFs designed in a 0.18 µm CMOS technology powered by a 1.0 V single supply: a folded-OTA based LPF and a mirrored-OTA based LPF. The first one exhibits a constant power consumption of 180 nW at 100 nA bias current with an active area of 0.00135 mm2 and a tunable cutoff frequency that spans over 4 orders of magnitude (~100 mHz–152 Hz @ CL = 50 pF) preserving dynamic figures greater than 78 dB. The second one exhibits a power consumption of 1.75 µW at 500 nA with an active area of 0.0137 mm2 and a tunable cutoff frequency that spans over 5 orders of magnitude (~80 mHz–~1.2 kHz @ CL = 50 pF) preserving a dynamic range greater than 73 dB. Compared with previously reported filters, this proposal is a competitive solution while satisfying the low-voltage low-power on-chip constraints, becoming a preferable choice for general-purpose reconfigurable front-end sensor interfaces.

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