106results about "Supply voltage control" patented technology

A method and apparatus for de-noising weak bio-signals having a relatively low signal to noise ratio utilizes an iterative process of wavelet de-noising a data set comprised of a new set of frames of wavelet coefficients partially generated through a cyclic shift algorithm. The method preferably operates on a data set having 2^N frames, and the iteration is performed N−1 times. The resultant wavelet coefficients are then linearly averaged and an inverse discrete wavelet transform is performed to arrive at the de-noised original signal. The method is preferably carried out in a digital processor.

The present invention provides a high frequency amplifier using a power supply voltage regulate circuit for the purpose of compensating for variations in power supply voltage. The high frequency amplifier comprises three-stage power amplifiers which amplify an input signal and output the amplified signal, a bias circuit which supplies bias voltages for controlling these power amplifiers, a regulate circuit which compensates for variations in noise or gain with respect to the variations in the power supply voltage for driving the power amplifiers, etc. The regulate circuit holds constant an output voltage Vddc with respect to variations in power supply voltage Vdd and outputs the constant-held output voltage Vddc as a power supply voltage for the power amplifiers.

A bias control circuit is provided comprising an input port for receiving a signal indicative of an amplitude of a supply voltage provided to a multi stage power amplifier circuit. Electronic circuitry, electrically coupled to the input port, generates a bias control signal in dependence upon the signal indicative of a supply voltage for provision to a first stage power amplifier of the multi stage power amplifier circuit. The bias control signal is generated such that a gain change of the multi stage power amplifier circuit due to a supply voltage change is substantially compensated.

A transmission output circuit can always perform correct transmission power control, and can detect the abnormality of transmission power, which interferes with other users, and part troubles, which cause erroneous transmission. The transmission output circuit includes transmission power control data generation means for generating a gain control signal for performing the feed forward control of gain control amplification means in order that the output signal level of the power amplification means may be a target transmission power output level, detection means for detecting the output signal of the power amplification means to obtain detected signal data, and judgment means for judging the existence of the occurrence of trouble in the transmission output system by using the detected signal data from the detection means.

A distortion compensation system minimizes distortion in an audio system by monitoring a supply voltage and adjusting a clipping threshold and/or compression knee. An adjustable gain circuit controls the gain of the audio signal according whether the audio signal exceeds a variable threshold. The variable threshold is adjusted within a threshold range based on the supply voltage. Distortion due to clipping of the audio signal is minimized while available power at any given time is maximized.

When a power amplifier operates near or in saturation, the quality of the output signal can be degraded and an over current condition can occur. To prevent this, the level of the power supply voltage being provided to the power amplifier must be monitored and controlled. One technique is to provide the supply power to the power amplifier through a pass transistor. By characterizing the resistance of the pass transistor and sensing the voltage drop across the pass transistor, the current being provided to the power amplifier can be determined. If this current is too high, the control input to the pass transistor can be adjusted to limit the current.

The invention concerns a method (300) and system (100) for controlling audio output. The method includes the steps of inputting (312) an audio signal and a voltage level signal, measuring (314) the audio signal and the voltage level signal, mapping (316) the audio signal against at least one table (134) of predetermined corresponding gain targets (138) and selecting (318) at least one gain target for the audio signal. The mapping step and the selecting step are based at least in part on the measurement of the voltage level signal and the measurement of the audio signal. The method also includes the step of applying (320) the gain target to the audio signal.

To provide an audio signal amplifier and an audio apparatus having the same that automatically set the output level to an optimum level depending on power supply voltage and so on. The audio signal amplifier of the present invention has an input terminal for receiving an audio signal from outside; a demodulating level control signal input terminal for receiving a demodulating level control signal; a variable-gain amplifying circuit for inputting a gain control signal and the audio signal and amplifying the audio signal at an amplifying factor in response to the gain control signal; a demodulating circuit for receiving the output signal of the variable-gain amplifying circuit and a demodulating signal feedback amount control signal and outputting a demodulating signal obtained by demodulating the output signal of the variable-gain amplifying circuit, the demodulating signal varying in level in response to the demodulating signal feedback amount control signal, as the gain control signal; a control circuit for adjusting demodulating level for outputting the demodulating signal feedback amount control signal generated in response to the demodulating level control signal; and a first output terminal for outputting the output signal of the variable-gain amplifying circuit.

Provided is an electronic device which can prevent operation stop attributed to lowering of an electronic device operation voltage. A pre-stage of a power amplifier (24) is connected to a capacitor and a first and a second current limit circuit. A CPU (21) monitors a voltage of the capacitor and corrects a gain of the power amplifier (24) in accordance with the voltage value. Moreover, when the electronic device includes a speaker system having a plurality of channels, an audio signal reproduction mode is switched, for example, between a stereo reproduction and a monaural reproduction according to the voltage value of the capacitor.

A power amplifier gain control system that monitors power supply voltage and changes the gain of the amplifier in response to changes in supply voltage. In systems subject to changes in supply voltage, such as in a battery powered system, the supply voltage can change over time. Reductions in the supply voltage may force the amplifier out of linear operation. A detector circuit compares the supply voltage in relation to one or more threshold values to determine if the supply voltage is less than a minimum nominal voltage. In response to the supply voltage falling below the minimal nominal voltage, amplifier gain is reduced to maintain amplifier linearity. A second threshold may be utilized in the comparison to the supply voltage when transitioning to the original gain level to prevent oscillation. A latching may be provided to prevent gain changes during active transmit periods.

While the amplification factor of an external amplifier is increased to raise the minimum volume level, synthesized speech of text data is generated as PCM data. When the PCM data is output for each frame (63 ms), the voltage of a battery power supply is detected and different ATT values (attenuation ratios) are set in accordance with threshold values (Level 1˜4) corresponding to the detected voltage. The lower the power supply voltage, the larger the attenuation ratios. The PCM data is attenuated by such an attenuation ratio to reduce a load to the battery power supply. Even though the battery power supply is exhausted to some extent, no power-down due to an instantaneous increase in power load occurs, with the result that a high-level part of a series of speech data items is output at an adequate volume level that makes a low-level part thereof easy to hear.

The present invention detects whether the supply voltage applied to the power supply terminal (3) is used for the dynamic speaker or for the piezoelectric speaker by the power supply voltage detection circuit (10), switches the gain of the amplifier circuit (8) in accordance with the detection result by the gain switching circuit (11) so that the same output power is produced for the same input signal in the respective speaker driving, and amplifies the input signal from the input terminal (5) by the amplifier circuit (8) having the gain to drive a speaker (1) that is connected to the output terminals (6, 7).

A power supply apparatus which supplies power to an amplifier, includes: a regulator stabilizing a voltage of the power supplied to the amplifier; and a stabilizing controller obtaining an amplitude level of an input signal inputted to the amplifier and controlling a stability of the voltage by the regulator based on the amplitude level.

A circuit configuration is provided for controlling the transmitting power of a battery-operated transceiver. A high transmitting power of a mobile transceiver generates a high voltage drop across an internal impedance of the battery which can lead to the device switching off. A reduction in the transmitting power in dependence on the battery voltage is therefore proposed. The battery voltage is thus compared with a reference voltage and a signal representing a nominal transmitting power is correspondingly corrected. The circuit can be integrated in a simple manner with analog components in an IC.

A method and apparatus for amplifying audio signals without exceeding an input current limit budgeted for the audio power amplifier circuit includes an intermediate energy storage between a battery and the audio power amplifier which provides an energy reserve to support amplifying peaks where the peaks have a peak power that is greater than the power that can be drawn from the battery due to the input current limit. Speech signals, which include substantial periodic content having short peaks relative to a pitch period, can be amplified without depleting the intermediate energy storage, allowing the intermediate energy storage to recover after a peak and before occurrence of a next peak. When an audio signal is amplified that results in depletion of the intermediate energy storage, a depletion recovery circuit reduces the overall audio gain to reduce the power demand of the audio power amplifier so as to substantially avoid distortion.

The present invention discloses an audio device having haptic compensation function capable of compensating a haptic effect according to a power measuring result and an audio signal. An embodiment of the audio device comprises: an audio signal generating circuit operable to generate an audio signal; a power measuring circuit operable to measure a remaining electric quantity of a power source and thereby generate a power measuring result; and a haptic compensating circuit, coupled to the audio signal generating circuit and the power measuring circuit, operable to adjust a gain of the audio signal or the derived signal thereof according to the power measuring result and thereby output a haptic compensation signal which is used to compensate the haptic effect.

In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Apparatus and methods for biasing a power amplifier are disclosed. In one embodiment, a method of biasing a power amplifier includes shaping an enable signal using a time-dependent signal generator to generate a control current, amplifying the control current using a current amplifier to generate a correction current, and generating a bias current for a power amplifier using a primary biasing circuit. The primary biasing circuit is configured to use the correction current to correct for a variation in gain of the power amplifier when the power amplifier is enabled.

To reduce the risk of brown outs and resets in a mobile station using a far-field speaker, a voltage level of a battery and a level of an input audio signal are monitored. When the level of the audio signal increases past a threshold level, and the voltage level of the battery falls below a threshold voltage, an attenuation is determined and applied to the audio signal. The applied attenuation reduces the volume of the audio signal, which reduces the risk of a brown out or a reset due to insufficient voltage in the mobile station.