Amplified Output Signal Research Articles

Performance assist apparatus of wind instrument

In an apparatus for assisting play of a wind instrument, an actuator is attached to the wind instrument for vibrating a portion of the wind instrument so as to assist play of the wind instrument. A microphone receives a vibration of a sound generated by the wind instrument and generates a vibration signal representing the vibration of the sound. A breath pressure sensor detects a pressure of a breath that is blown into the wind instrument during the play thereof, and generates a breath pressure signal corresponding to the detected pressure of the breath. A controller generates a control signal corresponding to the product of an inverse value of an envelope of the vibration signal and a value of the breath pressure signal. A variable gain amplifier amplifies the vibration signal with a variable gain which varies in response to the control signal so that an output signal of the variable gain amplifier is provided to enable the excitation part to vibrate the portion of the wind instrument.

Class-D amplifier and multi-level output signal generated method thereof

A class-D amplifier and a method of generating a multi-level output signal thereof are provided. The class-D amplifier includes a controlling logic circuit and an output module. The controlling logic circuit analyzes the amplitude of an input signal to generate a voltage modifying signal. A power supply provides a voltage according to the voltage modifying signal. The controlling logic circuit generates controlling signals according to the input signal. The output module generates an output signal to drive a load according to the voltage and the controlling signals. In other words, the resolution of the amplitude of the output signal is increased by modifying the voltage, and a signal to noise ratio is then increased.

MNAzymes, a Versatile New Class of Nucleic Acid Enzymes That Can Function as Biosensors and Molecular Switches

To increase the versatility and utility of nucleic acid enzymes, we developed multicomponent complexes, known as MNAzymes, which produce amplified “output” signals in response to specific “input” signals. Multiple oligonucleotide partzymes assemble into active MNAzymes only in the presence of an input assembly facilitator such as a target nucleic acid. Once formed, MNAzymes catalytically modify a generic substrate, generating an amplified output signal that heralds the presence of the target while leaving the target intact. We demonstrated several applications including sensitive, isothermal target detection; discrimination of polymorphisms; and highly specific monitoring of real-time polymerase chain reaction (PCR). Furthermore, we showed their capacity to function as molecular switches and to work in series to create a molecular cascade. The modular nature of MNAzymes, together with the separation of input and output functionalities, provides potential for their integration into diverse devices such as diagnostic biosensors, molecular computers, and/or nanoscale machines.

Gaussian Beams and Spatial Modulation in Nanopositioning

The kilogram is the last base unit of the systeme international d'unites (SI) that is still defined by an artifact. The watt-balance experiment is one of the promising methods that can produce a new definition of the kilogram based on fundamental constants. In this experiment, to compare an electromagnetic force and a gravitational force with a relative uncertainty of 10-9 by means of a beam balance, an absolute position sensor with nanometric resolution is needed. A novel method in position sensing based on the Gaussian beam propagation properties and their spatial modulation is presented. Two modulated and collimated Gaussian beams are focused into a slit. The slit is fixed to the object to be positioned. The resulting beams at the slit illuminate a photodetector whose signal is demodulated by a lock-in amplifier. The lock-in amplifier output signal is a function of the slit position with respect to the two modulated Gaussian beams. A resolution of 25 pm/(Hz)1/2 can be achieved. The long-term stability is 3.5 pm over 2 h and 20 min.

Extremum Seeking Control of Cascaded Raman Optical Amplifiers

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper considers the control of a particular type of optical amplifier that finds application in long-haul wavelength division multiplexed optical communications systems. The objective of this consideration is to demonstrate an application of extremum seeking to the regulation of amplifier output signal power across a range of signal wavelengths, where limited control authority is available. Although such amplifiers are nonlinear and distributed parameter devices, an extremum seeking design is demonstrated to be a promising approach for achieving the stated amplifier control objectives. </para>

System and method for minimizing DC offset in outputs of audio power amplifiers

An amplifier system receives an input signal and generating therefrom an amplified output signal. The amplifier system is recited as comprising an input stage and an amplifier stage. The input stage is configured to receive the input signal and provide a level-shifted signal that has an average signal level that is shifted in regards a level shift value. The amplifier stage is configured to receive the level-shifted input signal from the input stage and generate therefrom the amplified output signal. The level shift value being selected to minimize a DC offset in the amplified output signal at least when the amplifier system is initially powered on. Since the amplified output signal has a minimal or zero DC offset, the amplifier system avoids generation of undesirable noises when it is initially powered on.

A Data-Based Nested LUT Model for RF Power Amplifiers Exhibiting Memory Effects

In this letter, a new model is proposed for radio frequency power amplifiers exhibiting memory effects. The model is based on nested look-up tables that compute the estimated amplifier output signal, based on the current input sample and the preceding ones. The model is validated experimentally, using input and output waveforms of a high-power LDMOS based amplifier driven by a multicarrier WCDMA signal. It is shown that the performance of the proposed model is comparable to that of the conventional memory polynomial model. However, the nested look-up table based model significantly reduces the complexity of the identification of the model's parameters, as well as the computational complexity in calculating the estimated output signal.

병렬구조의 압력측정 시스템 개발

In this paper, we developed a pressure measurement apparatus with the parallel structure to improve the measurement efficiency of pressure sensors by reducing the measurement time of pressure. The developed system has two parallel positions for loading Silicon pressure sensor and has a dual valve structure. The semiconductor pressure sensors prepared by Copal Electronics were used to confirm the performance of the developed measurement system. Two stage differential amplifier circuit was employed to amplify the weak output signal and the amplified output signal was improved utilizing a low-pass filter. New apparatus shows the measurement time of pressure two times shorter than that of conventional one with the serial structure, while both structures show the similar linear output versus pressure characteristics.

Feedback compensation device and method, and hearing aid device employing same

A feedback compensator for a hearing aid device has a filter arrangement that splits a signal path, to implement an adaptive feedback compensation with only one buffer memory, two splitting nodes, and two addition nodes. The feedback compensation ensues only in the feedback-susceptible frequency range of the input signal. In addition to the filtering of the input signal, it is advantageous to feed to the adaptive feedback compensation filter a bandwidth-limited signal that is taken from the amplified output signal.

Design and analysis of large-area vertical-cavity semiconductor optical amplifiers with anti-resonant reflecting optical waveguide

The optical characteristics of antiresonant reflecting optical waveguide (ARROW) vertical-cavity semiconductor optical amplifiers (VCSOAs) are investigated theoretically. Influence of spatial hole burning (SHB) and thermal lensing on the stability of the amplified output signal is taken into consideration in the studies. A design rule, which can be used to deduce the optimized dimensions of ARROW, is developed to achieve spatially stable single-spot amplified output-signal in large-area VCSOAs. It can be shown that a high saturation power yet stable output signal can be achieved in large-area ARROW VCSOAs simultaneously.

ON LINEAR CONTROL OF BACKWARD PUMPED RAMAN AMPLIFIERS.

This paper considers the modelling and control of a particular type of optical amplifier that finds application in long-haul wavelength division multiplexed optical communications systems. The objective of this consideration is to design and demonstrate a simple (and potentially cheap) linear control strategy for regulating amplifier output signal power across a range of signal wavelengths in the presence of upstream signal power uncertainty, where limited control authority is available. Although such amplifiers are highly nonlinear and distributed devices, the straight-forward application of linearization, model reduction and ℋ∞ loopshaping design is demonstrated to be a promising approach for achieving the stated amplifier control objectives.

Beam combining using orientational stimulated scattering in liquid crystals

The possibility of beam combining and cleanup using orientational stimulated scattering in a nematic liquid crystal is considered. We numerically study the dynamics of the process and find that backconversion process tends to limit the effective interaction strength. The instability of the steady state of cross-phase modulation is demonstrated, during which both waves have the same frequency. We show that high conversion efficiency can be achieved and that the shape and wavefront of the amplified output signal are robust with respect to the amplitude and phase distortions of the input pump. copy 2005 Optical Society of America

Combine audio and ringing mode

A circuit where the same amplifiers and the same volume adjustment circuitry are used for the ringer mode as well as for the audio mode of a mobile phone is achieved. The volume adjustment in the audio and ringer mode is provided by a precise amplitude setting via the gain control stages of an inverting voltage amplifier used in a bridge circuit through a current-voltage conversion. This volume adjustment circuit avoids the high power dissipation of a volume control through pulse width modulation (PWM) and avoids the risk of over-and undershooting of the amplifier's output signal due to a high slew rate in combination with the inductance of the loudspeaker. The current-voltage conversion is performed by a series of resistors activated by a series of correspondent switches. High impedance current less sense paths are eliminating the parasitic effect of the resistance of low cost standard switches to adjust the volume of the loudspeaker in the audio and the ringer mode.

Phase control of nonadiabatic parametric amplification of spin wave packets

The influence of the phase shift between the signal and pumping wave on the process of parametric amplification of microwave spin wave pulses has been examined. The experiment was specifically made in the nonadiabatic regime, where the pumping field is strongly localized in a region on the order of the spin wave carrier wavelength. In this regime all previous experiments exhibited a strong random modulation (beating) of the amplified output signal. For a fixed phase shift between the signal and the pumping carrier waves the output signal was found to be stable, and no beating was observed. The amplitude of the amplified output pulse varies from the maximum value (corresponding to the maximum gain factor of 15 dB) to the minimum value (corresponding to almost no gain) when the phase shift between signal and pumping wave is changed. The measured phase interval between two consecutive minima in the phase dependence of the output power is equal to π.

A microphone array for hearing aids

A directional acoustic receiving system is constructed in the form of a necklace including an array of two or more microphones mounted on a housing supported on the chest of a user by a conducting loop encircling the user’s neck. Signal processing electronics contained in the same housing receives and combines the microphone signals in such a manner as to provide an amplified output signal which emphasizes sounds of interest arriving in a direction forward of the user. The amplified output signal drives the supporting conducting loop to produce a representative magnetic field. An electroacoustic transducer including a magnetic field pick-up coil for receiving the magnetic field is mounted in on the user’s ear and generates an acoustic signal representative of the sound of interest. The microphone output signals are weighted (scaled) and combined to achieve desired spatial directivity responses. The weighting coefficients are determined by an optimization process. By bandpass filtering the weighted microphone signals with a set of filters covering the audio frequency range and summing the filtered signals, a receiving microphone array with a small aperture size is caused to have a directivity pattern that is essentially uniform over frequency in two or three dimensions. This method enables the design of highly directive hearing instruments, which are comfortable, inconspicuous, and convenient to use. The invention provides the user with a dramatic improvement in speech perception over existing hearing aid designs, and particularly in the presence of background noise and reverberation.

A microphone array for hearing aids

A directional acoustic receiving system is a form of a necklace including an array of two or more microphones mounted on a housing supported on the chest of a user by a conducting loop encircling the user's neck. Signal processing electronics contained in the same housing receive and combine the microphone signals in such a manner as to provide an amplified output signal which emphasizes sounds of interest arriving in a direction forward of the user. The amplified output signal drives the supporting conducting loop to produce a representative magnetic field. An electroacoustic transducer including a magnetic field pick up coil for receiving the magnetic field is mounted in or on the user's ear and generates an acoustic signal representative of the sounds of interest. The microphone output signals are weighted (scaled) and combined to achieve desired spatial directivity responses. The weighting coefficients are determined by an optimization process. By bandpass filtering the weighted microphone signals, with a set of filters covering the audio frequency range, and summing the filtered signals, a receiving microphone array with a small aperture size is caused to have a directivity pattern that is essentially uniform over frequency in two or three dimensions. This method enables the design of highly-directive-hearing instruments which are comfortable, inconspicuous, and convenient to use. The array provides the user with a dramatic improvement in speech perception over existing hearing aid designs, particularly in the presence of background noise, reverberation, and feedback.

The interface amplifier and timing generator unit for control of operation of an off-line time-resolved X-ray spectrometer

This paper describes an on-site developed interface amplifier and timing generator unit for the control of operation of an X-ray spectrometer, aimed at obtaining off-line time-resolved pulse height analysis spectra, using a single channel of a digital transient recorder and a histogram algorithm. This unit, implemented in a low noise NIM module to be inserted between the amplifier and the transient recorder, generates a trigger pulse and time information for the digitizer, conditions the amplifier output signals to the digitizer input characteristics, reports the occurrence of pile-ups and prevents collisions between time and event pulses. Tests and operation on the TCV X-ray spectrometer have shown that the unit fulfils the design requirements.

Linearity in output signal of optical position-sensing detector systems

A precise operation of the position-sensing detectors (PSD) is exploited in this study. A position-sensing detector is modeled and the amplified output signal for this device as a result of input source current variation is studied. Beam displacement on such detectors is calculated and approximated and more accurate expressions for the generated signals are obtained. Linearity effect in output response of such a device is also investigated. The expansion coefficients for the signals are determined, which show the effect of the nonlinear terms. The first nonlinear coefficient is about 16.6% of the linear coefficient while the next terms are 2.5, 0.89, and 0.48% of the linear coefficient, respectively. For a position change of x=0.2 unit the linear term is 0.08, the third-order term −0.005328, and the fifth-order term is only about 0.000032, which is negligible. To see the operational result, using software simulates a PSD and the related circuit that provides the positional information.

Low-distortion CMOS complementary class E RF tuned power amplifiers

A low distortion tuned power amplifier which is suitable for integrated circuit implementation is proposed. The amplifier is a complementary class-E tuned power amplifier because of both P-type and N-type transistors are employed to achieve a highly symmetrical topology, thereby reducing the significant distortion in the output signal of the conventional single-ended class-E power amplifier. In this paper, a complementary class-E power amplifier is presented together with HSPICE simulation results.

Intrinsic thin film stresses in multilayered imaging pixels

When thin film devices are integrated in display or imaging arrays, the intrinsic mechanical stresses in the films can be severe enough to cause the films to either crack or even peel off the underlying substrate layer. This is a particular concern in large area x-ray imaging applications based on molybdenum/amorphous silicon (Mo/a-Si:H) Schottky diodes. This family of image sensors can be used for direct detection of x rays without the need for a phosphor layer [W. Zhao and J. A. Rowlands, Med. Phys. 22, 1595 (1995)]. In these sensors, the interaction of x-ray photons with Mo leads to injections of high energy electrons into a reverse-biased a-Si:H depletion layer, thereby producing an amplified output signal due to charge multiplication. The generated charge is read out by a thin film transistor (TFT) which is composed of intrinsic amorphous silicon (i-a-Si:H) as the active channel layer, silicon nitride (a-SiNx) as the insulating layer, and highly doped microcrystalline silicon (n+μc-Si:H) as the contact layer. For example, the i-a-Si:H layer is in compressive stress with a magnitude of 0.116 GPa, whereas low temperature, low resistivity n+μc-Si:H layer is in compressive stress of 1.47 GPa. The a-SiNx layer is in tensile stress of 0.222 GPa. The heavy metals used in the x-ray detector, such as Mo and chromium (Cr) (deposited at 5 mTorr), are found to be in tensile stress of 0.807 and 0.575 GPa, respectively. This article presents the internal mechanical stresses in thin film devices used in x-ray imaging, and more importantly, how the total film stress can be reduced without undermining device performance.