41results about "Limiting amplitude without controlling loop" patented technology

A method and apparatus are disclosed for listening to ambient sounds, engage in face-to-face communication, listen to and transmit voice communications, while also protecting the auditory system from hazardous sound pressure levels. Increased gain permits the user to maximize his sound detection ability during “reconnaissance and sentry” activities, thereby increasing the user's ability to detect and localize low level sounds such as, for example, enemy movement or activity. The throughput of the system is linear creating high fidelity of sound until the output level for a particular setting of the final gain reaches the limits established by the power supply. At that point, the output reaches a hard limit. This supply voltage also limits the output to the ear for any instantaneous increase in sound pressure levels. The invention includes barriers to attenuate ambient sounds from entering the ear canal and means for providing sound to the occluded portion of the ear canal. Therefore, hazardous impact noise (e.g., weapons blast, small arms fire, etc.) does not pass through the invention while ambient sounds and conversation are received at a level suitable for the auditory system.

An automatic input-gain control circuit of an audio amplifier and a method thereof are provided. If an acoustic signal exceeds a dynamic range, a gain of the acoustic signal can be automatically attenuated based on a pre-set limit level to minimize a distortion of the acoustic signal caused by clipping of the acoustic signal and limit an over-input so as to input the acoustic signal within the dynamic range. Thus, an original form of an over-input signal on a specific level or more can be maintained but only a gain of the over-input signal can be attenuated. As a result, a distortion of an output waveform caused by clipping of the output waveform can be minimized, and a harmonic distortion and a stepped high frequency noise occurring during clipping can be simultaneously removed.

Provided are input-gain control apparatus and method of an audio amplifier. A gain of an acoustic signal is automatically attenuated based on a pre-set limited level to minimize distortion of the acoustic signal caused by clipping of the acoustic signal, and thereby limit an over-input of the acoustic signal to input the acoustic signal within a dynamic range if the acoustic signal is not input within the dynamic range in an audio apparatus including an acoustic amplifier and a switching amplifier. Thus, only a gain of an over-input signal on a specific level or more can be attenuated while an original form of the over-input signal is maintained to minimize distortion of an output waveform caused by clipping of the output waveform. Also, a harmonic distortion and a stepped high frequency noise occurring during clipping can be simultaneously removed.

A limiter circuit passes, from input signal voltages, only a signal voltage component contained in a range between the input signal voltage and the upper limit signal voltage by the switching action of a pair of transistors. In this circuit, since the pair of transistors compare the input signal voltage and a threshold signal voltage and switch lines, simultaneously, there is no influence of the propagation delay speed and no switching noise occurs when switching lines. Moreover, since no diode is used, a high-speed limiter circuit can be fabricated.

The present invention relates to an electromagnetic signal power limiter and its design method. The power limiter for an electromagnetic signal includes at least one transmission line for the signal. The transmission line is made up of a number of passive micro-diodes with ballistic electron transport. The micro-diodes are distributed on the transmission line, and are implemented in a controlled atmosphere. The invention applies notably to radiofrequency or hyperfrequency waves received by detection and communication devices.

The present invention relates to a variable gain amplifier. The variable gain amplifier includes an input unit including first and second input nodes and an output node, the input unit being configured to receive first and second input signals. The variable gain amplifier further includes a first clipping unit operable to clip a voltage level at the output node to be equal to or lower than a level of a first reference voltage and a second clipping unit operable to clip a voltage level at the output node to be equal to or greater than a level of a second reference voltage, wherein the second reference voltage is lower than the first reference voltage. A predetermined level of a voltage is outputted through an output unit included in the variable gain amplifier based on the clipped voltage level.

A resistive radio frequency (RF) signal power limiter is for connection between an antenna and a receiver circuit in an RF receiver system. The receiver circuit may include a low noise amplifier (LNA). The resistive RF signal power limiter may include at least one positive temperature coefficient (PTC) thermistor connected in series, and at least one negative temperature coefficient (NTC) thermistor connected in shunt between the at least one PTC thermistor and a reference voltage.

An amplitude control system including one or more multi-element array power amplifiers (MEA-PA), each MEA-PA including multiple amplifiers, multiple capacitors, and multiple enable circuits. Each amplifier has an input coupled to a common input node and an output coupled to a corresponding one of multiple intermediate nodes. Each capacitor has a first end coupled to an output node and a second end coupled to a corresponding intermediate node. The enable circuits are collectively controlled by an amplitude control value, and each is operative to enable or disable a corresponding amplifier. The enable circuits may be dynamically controlled to modulate amplitude. A coupling circuit may be provided to couple an intermediate node to a reference node when a corresponding amplifier is disabled to adjust a coupling ratio. Each amplifier, when enabled, may receive one of multiple supply reference voltages. The capacitors may have equal capacitance or may be binary-weighted.

This document discusses, among other things, apparatus and methods for providing audio transducer protection. In an example, an audio protection circuit can include a first comparator configured to compare peak power information of a drive signal of an amplifier of an audio system with a first threshold, a limiter circuit configured to limit an input of the amplifier if the peak power information of the drive signal exceeds the first threshold, and a second comparator configured to compare average power information of the drive signal with a second threshold and to provide an output signal configured to modulate a gain of a pre-amplifier of the audio system using the comparison.

There is provided a buffer circuit that outputs a signal according to an input signal. The buffer circuit includes a first receiving transistor that receives the input signal through its base terminal, a first clamp transistor having polarity same as that of the first receiving transistor, of which an emitter terminal and a collector terminal are connected to corresponding terminals of the first receiving transistor and which receives a first clamp voltage restricting a signal level output from the buffer circuit through its base terminal, and a first current defining section that is commonly provided for the first receiving transistor and the first clamp transistor and defines a total amount of emitter currents flowing into the first receiving transistor and the first clamp transistor. The buffer circuit outputs an output signal according to an emitter voltage of the first receiving transistor.

A volume amplitude limiting device includes a volume adjustment unit, an amplitude limiting unit, and a control unit. The volume adjustment unit adjusts the amplitude of an input sound signal to a larger degree as the adjustment value increases and outputs the resulting sound signal. The amplitude limiting unit limits the amplitude of the sound signal output from the volume adjustment unit to an output limitation value and outputs the resulting signal to a speaker. The control unit sets an adjustment value for the volume adjustment unit and also sets an output limitation value for the amplitude limiting unit according to an adjustment value.

The present invention relates to an electromagnetic signal power limiter and its design method. The power limiter for an electromagnetic signal includes at least one transmission line for the signal. The transmission line is made up of a number of passive micro-diodes with ballistic electron transport. The micro-diodes are distributed on the transmission line, and are implemented in a controlled atmosphere. The invention applies notably to radiofrequency or hyperfrequency waves received by detection and communication devices.

A plasma power limiter fabricated using wafer-level fabrication techniques with other circuit elements. The power limiter includes a signal substrate having a first side and a second side, an input signal line formed on the first side, a signal transmission line formed on the second side and an output signal line formed on the first side. The power limiter also includes a ground substrate having a first side and a second side, and being bonded to the signal substrate to form a sealed cavity including an ionizable gas therebetween. The ground substrate includes a ground metal layer formed on the second side. A signal propagating on the input signal line at a power level greater than a threshold power level generates a voltage potential across the cavity that ionizes the gas and generates a plasma discharge, and limits power of the output signal coupled to the output signal line.

There is provided a buffer circuit that outputs a signal according to an input signal. The buffer circuit includes a first receiving transistor that receives the input signal through its base terminal, a first clamp transistor having polarity same as that of the first receiving transistor, of which an emitter terminal and a collector terminal are connected to corresponding terminals of the first receiving transistor and which receives a first clamp voltage restricting a signal level output from the buffer circuit through its base terminal, and a first current defining section that is commonly provided for the first receiving transistor and the first clamp transistor and defines a total amount of emitter currents flowing into the first receiving transistor and the first clamp transistor. The buffer circuit outputs an output signal according to an emitter voltage of the first receiving transistor.

The present invention relates to a variable gain amplifier. The variable gain amplifier includes an input unit including first and second input nodes and an output node, the input unit being configured to receive first and second input signals. The variable gain amplifier further includes a first clipping unit operable to clip a voltage level at the output node to be equal to or lower than a level of a first reference voltage and a second clipping unit operable to clip a voltage level at the output node to be equal to or greater than a level of a second reference voltage, wherein the second reference voltage is lower than the first reference voltage. A predetermined level of a voltage is outputted through an output unit included in the variable gain amplifier based on the clipped voltage level.

The invention provides a system for automatically regulating output volume of an electronic device. The electronic device comprises a sound sensor, a sound output unit and a PWM unit. The system sets an association relationship between a volume value of the sound output unit and a volume value of a surrounding environment, and sets a maximum volume value that ears can bear; when a user plays audio data, the system calculates the duty ratio of the PWM unit according to an environment volume value detected by the sound sensor, a volume value which is currently outputted by the sound output unit, a volume value which should be outputted by the sound output unit and is determined according to the association relationship, and the set maximum volume value that ears can bear; and the system outputs the duty ratio tot the PWM unit and drives the PWM unit to output corresponding PWM signals to the sound output unit so as to adjust the volume of sound output. The invention also provides a method for automatically regulating the output volume of the electronic device.

An electronic device includes an audio sensor, an audio output unit, a pulse width modulation (PWM) unit connected to the audio output unit, and a control chip. When the audio output unit outputs the audio signal, the audio sensor detects a volume level of the environment sound. The control chip determines a volume level of the audio signal according to the volume level of the environment sound and preset associations between volume levels of the audio signal outputted by the audio output unit and volume levels of the environment, and determines a duty cycle of the PWM unit according to the determined volume level and the maximum volume level. The control chip then outputs the duty cycle to the PWM unit, to adjust a current volume level of the audio signal outputted by the audio output unit to the determined volume level.

A voltage clamping module is disposed at an output terminal of a gain amplifying module, so that a voltage level of an amplifying signal outputted by the gain amplifying module can be clamped within a predetermined range. The voltage clamping module includes an upper bound voltage clamping module, which is utilized for limiting the voltage level of the amplifying signal to be lower than an upper bound voltage level, and a lower bound voltage clamping module, which is utilized for limiting the voltage level of the amplifying signal to be higher than a lower bound voltage level.

A circuit for processing an audio signal includes an input stage to which the audio signal is applied and an output at which the processed audio signal is presented. The circuit comprises first and second input stages (11, 12) having nonlinear performance curves, the first stage receiving the audio signal at a specified phase, and the second stage receiving from an inverter (13) an inverse phase of the audio signal. A positive half wave of the input signal is processed nonlinearly and the negative half wave is processed linearly. A difference amplifier (14) receives the signals produced by the first and second input stages and generates an audio signal representing a difference between the signals present at its inputs.

A plasma power limiter fabricated using wafer-level fabrication techniques with other circuit elements. The plasma limiter includes a signal substrate and a trigger substrate defining a hermetically sealed cavity therebetween in which is encapsulated an ionizable gas. The signal substrate includes a signal line within the cavity and the trigger substrate includes at least one trigger probe extending from the trigger substrate towards the transmission line. If a signal propagating on the transmission line exceeds a power threshold, the gas within the cavity is ionized creating a conduction path between the transmission line and the trigger probe that draws off the high power current.

A voltage clamping module is disposed at an output terminal of a gain amplifying module, so that a voltage level of an amplifying signal outputted by the gain amplifying module can be clamped within a predetermined range. The voltage clamping module includes an upper bound voltage clamping module, which is utilized for limiting the voltage level of the amplifying signal to be lower than an upper bound voltage level, and a lower bound voltage clamping module, which is utilized for limiting the voltage level of the amplifying signal to be higher than a lower bound voltage level.

A current control circuit with limiter includes a voltage follower as the output unit of the current control circuit, the voltage follower including a transistor, the circuit further including two operational amplifiers and two diodes. In a first operational amplifier, the non-inverting input receives an input voltage to the current control circuit and the inverting input receives the output of the voltage follower. In a second operational amplifier, the non-inverting input receives a predetermined voltage and the inverting input receives the output of the voltage follower. A first diode is connected between the output of the first operational amplifier and the input of the voltage follower. A second diode is connected between the output of the second operational amplifier and the input of the voltage follower.

An electronic device includes an audio sensor, an audio output unit, a pulse width modulation (PWM) unit connected to the audio output unit, and a control chip. When the audio output unit outputs the audio signal, the audio sensor detects a volume level of the environment sound. The control chip determines a volume level of the audio signal according to the volume level of the environment sound and preset associations between volume levels of the audio signal outputted by the audio output unit and volume levels of the environment, and determines a duty cycle of the PWM unit according to the determined volume level and the maximum volume level. The control chip then outputs the duty cycle to the PWM unit, to adjust a current volume level of the audio signal outputted by the audio output unit to the determined volume level.

A system for suppressing signal harmonic distortion caused by a main signal processing device provides processing for an electrical signal containing sine components of multiple frequencies. A post-processor reduces the amplitude of each frequency, relative to other frequencies, as the frequency increases, thus suppressing harmonics, which have higher frequencies than their respective elementary signals. To compensate for frequency distortion caused by the differential frequency suppression in the post-processing stage, a pre-processor provided upstream of the main signal processing device provides frequency-dependent signal processing having a generally opposite effect to that of the post-processor, increasing the amplitude of each frequency of the signal passing through the pre-processor, relative to other frequencies, as the frequency increases. The resulting output signal thus has substantially the same frequency spectrum as the original signal while distortion-causing harmonics are reduced or eliminated.

A plasma power limiter fabricated using wafer-level fabrication techniques with other circuit elements. The plasma limiter includes a signal substrate and a trigger substrate defining a hermetically sealed cavity therebetween in which is encapsulated an ionizable gas. The signal substrate includes a signal line within the cavity and the trigger substrate includes at least one trigger probe extending from the trigger substrate towards the transmission line. If a signal propagating on the transmission line exceeds a power threshold, the gas within the cavity is ionized creating a conduction path between the transmission line and the trigger probe that draws off the high power current.

A voice signal clipping circuit comprising, an amplifier which amplifies an input voice signal to a permissible level and a clipper which clips an amplitude component in excess of the permissible level from an output signal from the amplifier.

A volume amplitude limiting device includes a volume adjustment unit, an amplitude limiting unit, and a control unit. The volume adjustment unit adjusts the amplitude of an input sound signal to a larger degree as the adjustment value increases and outputs the resulting sound signal. The amplitude limiting unit limits the amplitude of the sound signal output from the volume adjustment unit to an output limitation value and outputs the resulting signal to a speaker. The control unit sets an adjustment value for the volume adjustment unit and also sets an output limitation value for the amplitude limiting unit according to an adjustment value.

The invention discloses a transmitter (300, 400, 600) comprising a pulse encoder (305) for creating pulses from the amplitude of an input signal to the transmitter, a compensation signal generator (315) for cancelling quantization noise caused by the pulse encoder (305), a mixer or I / Q modulator (307) for mixing an output of the pulse encoder with the phase of an input signal to the transmitter and an amplifier (320) for creating an output signal from the transmitter. In the transmitter (300, 400, 600), a control signal (CA) for controlling a function of the amplifier (320) comprises an output signal from the compensation signal generator (315), and an input signal to the amplifier (320) comprises an output from the mixer (307) having been modulated (340) to a desired frequency.