65 results about "Audio power amplifier" patented technology

A circuit for converting an analog signal to a discrete pulse-width-modulated (PWM) signal uses a delta-sigma amplifier and a discrete PWM stage to produce a discrete PWM output signal having lower in-band signal noise then a PDM system and a lower signal distortion then a continuous PWM system. A multiple bit quantization stage drives the discrete PWM stage.

The invention relates to a method and circuit for linearizing amplifiers and other nonlinear circuits for multi-carrier signals. An output signal from the amplifier is sampled, and a correlation matrix of size N×N is computed from the sampled signal, wherein N exceeds the number of multiplexed carriers in the signal. A signal-to-distortion ratio (SDR) is then estimated based on a ratio of one or more largest to one or more smallest eigenvalues of the correlation matrix, and the signal into the amplifier is pre-distorted so as to maximize the SDR.

A multiple-channel audio processor (10) and an associated plurality of power stages (22) in an audio system are disclosed. The audio processor (10) includes a plurality of audio amplifier channels (22), each of which includes a pulse-code-modulation (PCM) to pulse-width-modulation (PWM) conversion function (25), which generates PWM signals for application to the plurality of power stages (22). The audio amplifier channels (20) each also include an interchannel delay function (28) for delaying the PWM edges relative to other channels (20), for reducing noise. The audio amplifier channels (20) each also include delay adjust circuitry (32) for gradually increasing and decreasing the interchannel delay of the channel (20) on startup and shutdown. This permits a single control terminal (VALID) at the processor to globally enable and disable all of the power stages (22).

An opto-electronic converter includes a plurality of light-receiving elements configured to convert light of different colors into analog signals, each of the analog signals representing a pixel, an amplifier unit configured to amplify the analog signals, into which the light is converted by the light-receiving elements, in each pixel group, the pixel group including a plurality of the light-receiving elements, the plurality of light-receiving elements converting light of different colors, and a gain switch unit configured to switch, for each of the light-receiving elements included in the pixel group, a gain of the amplifier unit to a gain determined in advance depending on a color of the light converted by the light-receiving element.

A transconductance amplifier mirror circuit is connected to an electrode for sensing the capacitance of the electrode with reference to ground, or the capacitance between the electrode and another electrode. A voltage level change is produced on the electrode connected to the transconductance amplifier mirror circuit to cause the transconductance amplifier mirror circuit to supply charges to or drain charges from a charge calculation circuit. The charge amount variation is converted to a signal for calculating the sensed capacitance.

The present disclosure illustrates a feedforward controlled envelope modulator and a feedforward control circuit thereof. The feedforward controlled envelope modulator comprises a linear amplifier circuit, a switching amplifier, and a feedforward control circuit. The linear amplifier circuit amplifies an input voltage signal, so as to output an output voltage signal to a load node. The switching amplifier receives a comparison signal, and outputs a switching current to the load node according to the comparison signal. The feedforward control circuit comprises a duplicate linear amplifier circuit and a hysteresis comparator. The duplicate linear amplifier circuit amplifies the input voltage signal, so as to output a reference voltage signal, wherein an amplifying gain of the duplicate linear amplifier circuit is identical to an amplifying gain of the linear amplifier circuit. The hysteresis comparator compares the output voltage signal and the reference voltage signal, so as to output the comparison signal.

The present invention includes error amplifier, current output sample circuit, current configuring circuit, and current limiting loop amplifier; wherein said current limiting loop amplifier output end connected with passage-way element input end to form current limiting loop, passage-way element locking current on maximum output enable current through loop action.

The invention discloses a chopper-type direct current detection method and a circuit. A forward voltage and a backward voltage of two ends of a shunt resistor are continuously collected in real time through a certain frequency. A sampling value of a first half of a chopper period and a sampling value of a second half of the chopper period in a same chopper period are calculated and influences of a low-frequency noise, an offset voltage and other noises on a detection result are eliminated. The detection circuit comprises a shunt resistor, a simulation switch, an amplifier, an analog-to-digital converter and a control unit. The simulation switch is connected in parallel to two ends of the shunt resistor. An input terminal of the amplifier is connected to an output terminal of the simulation switch. An input terminal of the analog-to-digital converter is connected to an output terminal of the amplifier. An input terminal of the control unit is connected to an output terminal of the analog-to-digital converter. An output terminal of the control unit is connected to a control signal input terminal of the simulation switch. On one hand, the control unit provides a digital signal to control switching of the simulation switch; on the other hand, according to digital forward and backward voltage signal, the control unit acquires a direct current detection value. A circuit structure provided in the invention is simple; test accuracy is high and cost is low.

A class D amplifier with output DC offset protection is disclosed. The DC offset protection receives a PWM input signals from the outputs and investigates the PWM output signals whether there is a large DC voltage difference is being reflected on the speaker load. If so, shutdown signal SD will be sent by the DC offset protection to the PWM control logic and gate driver, thus, shutting down the output of the class D system and preventing disastrous condition from being develop across the speaker.

A fluid ejection device includes: a modulator adapted to pulse-modulate a drive waveform signal forming a basis of a drive signal of an actuator to obtain a modulated signal; a digital power amplifier circuit adapted to power-amplify the modulated signal to obtain a power-amplified modulated signal; a low pass filter adapted to smooth the power-amplified modulated signal to obtain the drive signal; and a power amplification stopping section operating when holding a voltage of the actuator constant.

The invention relates to an active sound eliminator for a ventilation pipeline system. The active sound eliminator comprises an outer shell, an inner pipe segment, a loudspeaker unit, an error microphone and a loudspeaker power amplifier board card. The outer shell comprises a sealing cover and a shell body, the sealing cover is of a plate-shaped structure with an opening in the center, the shell body is of a barrel-shaped structure with an opening in the bottom central position, one end of the inner pipe segment penetrates through the hole in the center of the sealing cover and is fixed to the sealing cover, the other end of the inner pipe segment is embedded in the hole in the center of the shell body, and the sealing cover is arranged on the top of the shell body. The loudspeaker unit, the error microphone and the loudspeaker power amplifier board card are respectively arranged on the periphery of the inner pipe segment, an output interface of the loudspeaker power amplifier board card is connected with the loudspeaker unit, and a signal input interface and a power source interface of the loudspeaker power amplifier board card and an output interface of the error microphone are led out through an electric connector arranged on the shell body. An annular flange for containing the loudspeaker unit is arranged on the side face of the inner pipe segment, and a plurality of penetrating holes exist in the position, corresponding to the mounting positions of the loudspeaker unit and the error microphone, of the wall of the inner pipe segment.

The invention discloses a circuit for a low-voltage adjustable band-gap reference source. Collectors and bases of three PNP triodes are grounded; the emitter of the first PNP triode is connected with one end of a first resistor; the other end of the first resistor is connected with the positive input end of an operational amplifier and the drain of a first P-channel metal oxide semiconductor (PMOS) transistor; the emitter of the second PNP triode is connected with the negative input end of the operational amplifier and the drain of a second PMOS transistor; the emitter of the third PNP triode is connected with one end of a second resistor; the other end of the second resistor is connected with the drain of a third PMOS transistor and one end of a third resistor; the other end of the third resistor is grounded; the output end of the operational amplifier is connected with the grids of the three PMOS transistors; and the sources of the three PMOS transistors are connected with a power supply. According to the circuit, configurable reference output voltage can be realized; and the influence of offset voltage of the operational amplifier on a starting circuit is avoided.

The invention discloses a low-power consumption bandwidth multiplication chopping stabilized operational amplifier based on an MOS (metal oxide semiconductor) device, which belongs to the field of design of analog integrated circuits. The low-power consumption bandwidth multiplication chopping stabilized operational amplifier comprises two frequency mixers, a shunt input stage, an intermediate stage for amplifying recovered current and a rail-to-rail output stage, wherein one frequency mixer is placed in front of an amplifier input stage, and the other frequency mixer is placed behind an amplifier output stage, thereby realizing the functions of raising frequency and reducing frequency of input signals; the shunt input stage is used for converting input voltage signals to current signals and forming small signal current in forward and backward directions; the intermediate stage for amplifying the recovered current comprises four low-voltage current mirrors and can realize the amplification of the recovered current; and the rail-to-rail output stage is used for realizing the rail-to-rail output of the signals. The low-power consumption bandwidth multiplication chopping stabilized operational amplifier has the capacity of improving bandwidth by nearly three times under the situation of not obviously increasing power consumption, and can reduce low-frequency 1/f noise, increase low-frequency gain, and reduce power consumption above one half while keeping the same bandwidth, the noise and other performances, thereby further improving the performances of the circuit.

An output circuit comprises first and second transistors, a driving circuit and a current mirror circuit. The driving circuit supplies a relatively small constant current to the base of the first transistor. When a current flows to the collector of the first transistor, a current with a magnitude set at a fixed ratio with respect to the current flows to the collector of the second transistor, and a current proportional to the current flowing to the collector of the second transistor flows to the base of the first transistor by way of the current mirror circuit. That is, a current, which is determined in accordance with a current flowing to the collector of the first transistor, flows to the base of the first transistor.

A sensor device is provided with a voltage detection type sensor unit for converting a physical quantity into a voltage value and outputting a voltage signal indicating the voltage value; a chopper amplifier unit for generating a modulation signal by chopping the voltage signal output from the sensor unit with a predetermined chopping frequency, amplifying the modulation signal into an amplification signal, then demodulating the amplification signal and outputting it as an output signal; an integration unit including an operational amplifier, an input resistor connected to the inverting input terminal of the operational amplifier and a capacitor connected between the inverting input terminal and an output terminal of the operational amplifier; and a digital conversion unit for converting the output signal integrated by the integration unit into a digital signal.

The invention discloses a reference adjustable programmable linear hall sensor chip comprising a hall plate, a chopping amplifier, a reference voltage control circuit, an adjustable gain amplifier and a static output control circuit. The hall plate induces a magnetic field signal and converts the magnetic field signal into a hall voltage signal which enters the adjustable gain amplifier through detuning elimination by the chopping amplifier. The reference voltage of the chopping amplifier is controlled by the reference voltage control circuit, the gain of the adjustable gain amplifier is controlled by a gain adjusting circuit, and zero output of the static output control circuit is controlled and adjusted by a zero adjusting circuit. The advantages of the reference adjustable programmable linear hall sensor chip are that 1, internal reference output can be realized, and external reference input is allowed so that the static output voltage is enabled to follow the external reference voltage; 2, the consistency of the static output voltage can be realized so that the problem of different output voltage caused by manufacturing technology error can be solved; and 3, the size of the gain can be accurately controlled.

The invention relates to a program controlled trigger and a method. A Hall current sensor senses current of a welding machine and outputs a voltage sensing signal; a signal amplifier amplifies the voltage sensing signal; a Schmitt trigger processes the amplified voltage sensing signal and triggers to generate a square signal; a singlechip captures rising edges and falling edges of the square signal, counts, and generates a pulse signal when a counting value reaches a set value; the singlechip regulates and controls the position of a tap of a digital potentiometer; an outputting pulse circuit outputs the pulse signal to an external high-speed camera; and the digital potentiometer regulates a forward threshold value and a reverse threshold value of the Schmitt trigger according to the position of the regulated and controlled tap, and carries out program control on the threshold values and pre-amplification times. Compared with the prior art, the program controlled trigger runs stably, carries out program control on the threshold values and the pre-amplification times, and can adapt to different welding environments.

The invented digital sinewave generator E is connected with sensor, multiway switch M and one end of amplifier M, and another end of amplifier M is sequence-cojnnected with multiway switch A, multiplier A, filter A, A/D converter A and computer, and another end of amplifier M also is sequence-connected with multiway switch B, multiplier B, filter B, A/D converter B and computer; the digital sinewave generator E is respectively connected with multiway A and multway B; the digital sinewave generator A is respectively connected with computer and multiplier A, the digital sinewave generator B is respectively connected with computer and multiplier B. When it is used for demodulatino, the computer controls the sinewave generators of E, A and B to make them respectively output actuating signals of E, A and B, through multiway switches, multipliers.

A method for controlling amplified signals in a medical diagnostic device having an amplifier system that is adapted to amplify input signals having a baseline and filter means for filtering the amplified signals, comprising the detection of the presence of an amplified signal having an amplitude that is above an upper voltage threshold or below a lower voltage threshold, and freezing the baseline of the amplified signal upon the detection thereof.

A sight distance visibility meter and a measuring method thereof can simulate light sensitivity of human normal vision truly to obtain atmospheric visibility distance directly and truly, and relate to the fields of real-time monitoring of agglomerate fogs in highways and atmospheric visibility distance measurement. The sight distance visibility meter comprises a target body, and an optical amplifier, a near infrared plane array CCD (charge coupled device) and an embedded signal processing unit which are connected sequentially, as well as a fog energy actuator arranged between the target body and the optical amplifier. Compared with the digital camera visibility distance measurement method, the method provided by the invention has the advantages of all-weather, high measurement accuracy, good stability, simple structure, small volume, low cost and the like due to the fact that the method does not needed a scene reference, is free from the affects of environmental factors like light and temperature in the atmospheric environment and acts no matter day and night, and the method is applicable for the real-time measurement of distance visibility and highway agglomerate fog monitoring needing intensive stationing.

A high frequency electronic component includes a switch and a balun. The switch performs switching between a first transmission signal in the form of an unbalanced signal received at a first input port and a second transmission signal in the form of an unbalanced signal received at a second input port, and outputs one of the first and second transmission signals from an output port. The balun converts the transmission signal in the form of an unbalanced signal outputted form the output port of the switch to a transmission signal in the form of a balanced signal, and outputs this signal to a balanced input power amplifier.

A memory apparatus may include a bit line sense-amplifier coupled to first and second bit lines; a first precharge unit suitable for coupling the first and second bit lines in response to a bit line equalization signal; a sense-amplifier power control unit suitable for providing a plurality of powers to the bit line sense-amplifier in response to a power control signal; and a second precharge unit suitable for individually changing each voltage level of the first and second bit lines based on a precharge control signal.

An amplifier circuit includes an amplification unit and a back-bias voltage providing unit. The amplification unit amplifies input data. The back-bias voltage providing unit provides selectively back-bias voltages of different levels to the amplification unit in an initial operation period of the amplification unit and a period after the initial operation period.

The invention particularly relates to a memristor-based automatic gain control circuit. The technical scheme is as follows: the circuit consists of a variable gain amplification module (1), a comparator (4) and a peak value detection module (5); the variable gain amplification module (1) consists of an operational amplifier circuit (2) and a memristor (3); a terminal M2 of the memristor (3) is connected with an input end Rc of the operational amplifier circuit (2); an input end Vi of the operational amplifier circuit (2) is externally connected with an input signal Vin; an output end VVGA of the operational amplifier circuit (2) is respectively connected with an input end VVGAP of the peak value detection module (5) and the input end Vw of a peripheral circuit; a terminal M1 of the memristor (3) is connected with an output end Vc of the comparator (4); an input end ViVGAP of the comparator (4) is connected with an output end ViVGA of the peak value detection module (5); and an input end VREF1 of the comparator (4) is externally connected with a reference electric level VREF. The memristor based automatic gain control circuit provided by the invention has the advantages of simple structure, low cost and high accuracy.