A Low-Frequency Filter in Inertial Applications

2015 ◽  
Vol 645-646 ◽  
pp. 875-880
Author(s):  
Qiang Li ◽  
Xiao Wei Liu ◽  
Liang Yin ◽  
Jia Jun Zhou
Keyword(s):  
Large Time ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Frequency Filter ◽  
Time Constants ◽  
Operational Transconductance Amplifiers ◽  
Technical Requirements ◽  
Low Pass ◽  
Transconductance Amplifiers ◽  
Current Shunt

A fourth-order cascade low-pass transconductance capacitor filter is designed, and the coefficients of the filter are calculated. For the implementation of large-time constants the current shunt technique and the current cancellation technique are employed in the operational transconductance amplifiers. The whole filter is simulated in Hspice, the the cutoff frequency is 150.2Hz and the THD of the filter is 65dB, which meet the technical requirements of the inertial applications.

A New Capacitance Multiplier Structure with High Multiplication Factor for Ultra-Low-Frequency Filter in Biomedical Applications

2019 ◽  
Vol 29 (07) ◽  
pp. 2050109
Author(s):  
Yan Li ◽  
Yong Liang Li
Keyword(s):  
Biomedical Applications ◽  
Low Frequency ◽  
Multiplication Factor ◽  
Frequency Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Physiological Signal ◽  
Wide Range ◽  
Low Pass ◽  
Capacitance Multiplier

A novel capacitance multiplier is proposed to implement an ultra-low-frequency filter for physiological signal processing in biomedical applications. With the proposed multiplier, a simple first-order low-pass filter achieves a [Formula: see text]3-dB frequency of 33.4[Formula: see text]μHz with a 1-pF capacitance and a 20[Formula: see text]k[Formula: see text] resistance. This corresponds to a multiplication factor of as large as [Formula: see text]. By changing the controlling terminal, the [Formula: see text]3-dB frequency can be tuned in a wide range of 33.4[Formula: see text]μHz–6.3[Formula: see text]kHz.

Acoustic Measurements of Objective Tinnitus

1990 ◽  
Vol 33 (4) ◽  
pp. 816-821 ◽  
Author(s):  
Craig A. Champlin ◽  
Stephen P. Muller ◽  
Stephen A. Mitchell
Keyword(s):  
Jugular Vein ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Masking Effect ◽  
Hearing Sensitivity ◽  
Normal Limits ◽  
Objective Tinnitus ◽  
Low Pass ◽  
Vascular Origin ◽  
One Year

Ear canal sound pressure levels were measured from a 38-year-old woman who had experienced objective tinnitus in her right ear for approximately 2 years. The tinnitus sounded like a series of “sighs” that were synchronous with her pulse rate. Because the level of the tinnitus fluctuated in a pulsing manner, it appeared to be of vascular origin. Psychoacoustically, the tinnitus behaved like a low-pass masker (cutoff frequency = 1.5 kHz) of about 40 dB SPL. This masking effect was manifested as a low-frequency hearing loss in the subject’s right ear. A miniature microphone system was used to monitor the tinnitus before, during, and after a jugular-vein ligation. Because the cause of the tinnitus was only generally known, acoustically monitoring the sound as the jugular vein and/or its tributaries were systematically clamped and then released enabled the site of generation to be known exactly. By monitoring the tinnitus during surgery, the effectiveness of the corrective procedure could be immediately evaluated. Hearing sensitivity in the affected ear returned to normal limits following the elimination of the tinnitus. One year after the surgery, the tinnitus was barely audible to the woman, but only when she positioned her head a specific way. The level of the tinnitus measured in this head-turned condition was markedly lower than the level obtained preoperatively.

scholarly journals Digitally Programmable Integrator and Differentiator

1995 ◽  
Vol 17 (4) ◽  
pp. 261-268
Author(s):  
Abdulrahman Khalaf Al-Ali ◽  
Muhammad Taher Abuelma'atti ◽  
Syed Yunus
Keyword(s):  
Operational Amplifier ◽  
Experimental Results ◽  
Time Constants ◽  
Operational Transconductance Amplifiers ◽  
Digitally Programmable ◽  
Transconductance Amplifiers

Digitally programmable integrator and differentiator circuits are presented. Each circuit uses at most one operational amplifier, two operational transconductance amplifiers, and one capacitor. The time constants of the circuits are decided by the biasing currents of the operational transconductance amplifiers. The circuits can be easily interfaced with microprocessor-based systems. Experimental results are included.

Nonlinear inversion of gravity data using the Schmidt‐Lichtenstein approach

Geophysics ◽  
1987 ◽  
Vol 52 (1) ◽  
pp. 88-93 ◽  
Author(s):  
Harald Granser
Keyword(s):  
Power Series ◽  
Gravity Anomaly ◽  
Series Expansion ◽  
Gravity Data ◽  
Inverse Operator ◽  
Cutoff Frequency ◽  
Power Series Expansion ◽  
Low Frequency ◽  
Nonlinear Inversion ◽  
Low Pass

The nonlinear inversion of the gravity from a single density interface can be performed through a power series expansion. The method is based on the Schmidt‐Lichtenstein approach for solving nonlinear integral equations. After expanding the nonlinear integral operator for the gravity effect as an operator power series, the inverse operator series is found by applying a technique formally equivalent to the classical inversion scheme of a scalar power series. Unlike the forward power series expansion, however, the convergence of the inverse series is restricted to a low‐frequency domain, characterized by a cutoff frequency that is dependent upon the amplitude of the gravity anomaly, the magnitude of the density contrast, and the mean depth of the interface. To ensure the stability of the inversion scheme, a suitable low‐pass filtering has to be performed. By taking advantage of the noniterative nature of the inversion scheme and the fast Fourier transform, the method is efficiently applied to invert a profile‐like, simulated model and a 3-D field example (the Malcov gravity anomaly) caused by a small sedimentary basin in the East Slovakian Outer Carpathians.

The Dynamics of Integrate-and-Fire: Mean Versus Variance Modulations and Dependence on Baseline Parameters

2011 ◽  
Vol 23 (5) ◽  
pp. 1234-1247 ◽  
Author(s):  
Joanna Pressley ◽  
Todd W. Troyer
Keyword(s):  
Firing Rate ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
High Frequencies ◽  
Integrate And Fire ◽  
Poisson Input ◽  
Low Pass ◽  
Mean And Variance ◽  
The Mean ◽  
Frequency Modulations

The leaky integrate-and-fire (LIF) is the simplest neuron model that captures the essential properties of neuronal signaling. Yet common intuitions are inadequate to explain basic properties of LIF responses to sinusoidal modulations of the input. Here we examine responses to low - and moderate-frequency modulations of both the mean and variance of the input current and quantify how these responses depend on baseline parameters. Across parameters, responses to modulations in the mean current are low pass, approaching zero in the limit of high frequencies. For very low baseline firing rates, the response cutoff frequency matches that expected from membrane integration. However, the cutoff shows a rapid, supralinear increase with firing rate, with a steeper increase in the case of lower noise. For modulations of the input variance, the gain at high frequency remains finite. Here, we show that the low-frequency responses depend strongly on baseline parameters and derive an analytic condition specifying the parameters at which responses switch from being dominated by low versus high frequencies. Additionally, we show that the resonant responses for variance modulations have properties not expected for common oscillatory resonances: they peak at frequencies higher than the baseline firing rate and persist when oscillatory spiking is disrupted by high noise. Finally, the responses to mean and variance modulations are shown to have a complementary dependence on baseline parameters at higher frequencies, resulting in responses to modulations of Poisson input rates that are independent of baseline input statistics.

Hilbert low-pass filter of non-stationary time sequence using analytical mode decomposition

2015 ◽  
Vol 23 (15) ◽  
pp. 2444-2469 ◽  
Author(s):  
Zuo-Cai Wang ◽  
Yu Xin ◽  
Jin-feng Xing ◽  
Wei-Xin Ren
Keyword(s):  
Cutoff Frequency ◽  
Low Frequency ◽  
Frequency Component ◽  
Sampling Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Mode Decomposition ◽  
Low Pass ◽  
One Step ◽  
Low Pass Filters

In this paper, the recently developed analytical mode decomposition with a constant or time-varying cutoff frequency is extended into the decomposition of a non-stationary discrete time sequence. The discretization of the signal and the selection of the cutoff frequency may cause the failure of low frequency component extraction. In this study, to eliminate the effects of the signal discretization, the one-step, two-step, and four-step low-pass filters with cutoff frequencies are proposed. Based on the theoretical derivation, the previous one-step low-pass filter is effective only when the cutoff frequency is not greater than a quarter of the sampling frequency and the maximum frequency of the signal not greater than a half of the sampling frequency. In this study, if the cutoff frequency is less than or equal to a quarter of the sampling frequency, a two-step low-pass filter is proposed to extract the low frequency component. If the cutoff frequency is greater than a quarter of the sampling frequency, a four-step low-pass filter with frequency shifting process is proposed. When the time-varying cutoff frequency is not always larger than or less than a quarter of the sampling frequency, a sufficient condition, which is the sampling frequency is greater than four times of the maximum frequency of the signal component, is provided in this study. Two numerical examples are used to validate the effectiveness of the proposed low-pass filters. Both the theoretic derivation and numerical simulations show that the proposed filters can analytical extract the discrete low frequency component with an appropriate cutoff frequency.

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.

scholarly journals Determination of the Distribution of Relaxation Times by Means of Pulse Evaluation for Offline and Online Diagnosis of Lithium-Ion Batteries

Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 36
Author(s):  
Erik Goldammer ◽  
Julia Kowal
Keyword(s):  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Sampling Rate ◽  
Relaxation Times ◽  
Low Frequency ◽  
Lithium Ion ◽  
Battery Management ◽  
Time Constants ◽  
Time Domain Data ◽  
Aging Study

The distribution of relaxation times (DRT) analysis of impedance spectra is a proven method to determine the number of occurring polarization processes in lithium-ion batteries (LIBs), their polarization contributions and characteristic time constants. Direct measurement of a spectrum by means of electrochemical impedance spectroscopy (EIS), however, suffers from a high expenditure of time for low-frequency impedances and a lack of general availability in most online applications. In this study, a method is presented to derive the DRT by evaluating the relaxation voltage after a current pulse. The method was experimentally validated using both EIS and the proposed pulse evaluation to determine the DRT of automotive pouch-cells and an aging study was carried out. The DRT derived from time domain data provided improved resolution of processes with large time constants and therefore enabled changes in low-frequency impedance and the correlated degradation mechanisms to be identified. One of the polarization contributions identified could be determined as an indicator for the potential risk of plating. The novel, general approach for batteries was tested with a sampling rate of 10 Hz and only requires relaxation periods. Therefore, the method is applicable in battery management systems and contributes to improving the reliability and safety of LIBs.

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