1419results about "Amplifier protection circuit arrangements" patented technology

A modular broadband transmission system and method include an input signal connector that receives an input signal which is then divided into N parts and amplified with an amplifier have N power amplifier modules. Outputs of the N power amplifier modules are passed through transmission lines and to a radial combiner that combines the outputs. The radial combiner, transmission lines and power amplifier modules are configured such that if one of the power amplifier modules fails, the other power amplifier modules may still operate acceptable well, with minimal impact on total output power. An output of the amplifier is provided to a coupler that measures a power level of the output signal and feeds the measured power level back to a controller where the controller adjust an overall output power based on the number of the power amplifier modules that are functioning properly. Each of the power amplifier modules have a processor such that respective of the power amplifier modules may be taken off-line, and replaced while the other power amplifier modules continue to operate in a transmit mode of operation. The modular broadband transmission system and method may conveniently be used as either a broadband booster for amplifying a plurality of input signals, or a head and transmitter configured to amplify one or more different input signals.

A method and an arrangement for detecting impedance mismatch between an output of a radio frequency amplifier (200, 901, 911, 921, 1101) which has an amplifying component (201, 301, Q46, 701, 801) and an input of a load (203, 302) coupled to the output of the radio frequency amplifier having: first monitoring means (401) to monitor a measurable electric effect (311) at a side of the amplifying component (201, 301, Q46, 701, 801) other than the load (203, 302) and to produce a first measurement signal (411). Second monitoring means (402) monitor a measurable electric effect (312) between the amplifying component (201, 301, Q46, 701, 801) and the load (203, 302) and produce a second measurement signal (412). Decision-making means (204, 902, 912, 923, 1102) receive said first (411) and second (412) measurement signals and decide, whether said first and second measurement signals together indicate impedance mismatch.

The present invention provides for dynamic insertion loss control for a 10/100/1000 megahertz Ethernet power on differential cable pairs. A power feed circuit supplies power to a network attached device (PD). An insertion loss control circuit limits power loss in a coupled power feed circuit. The insertion loss control circuit determines an insertion loss limit and senses an average power of the power signals to produce a common mode feedback signal to the power feed circuit. The insertion loss limit is determined for the received signals based on a differential RMS of the received Ethernet power signals as seen by a differential transistor pair. Alternatively, the insertion loss limit may be determined logically by the higher layers of the network protocol based on the AC differential portion of the network power signal. When the insertion loss limit is determined based on the differential RMS, the insertion loss control circuit is operable to automatically reduce the insertion loss based upon transmission losses experienced over the network connection between the power sending equipment and network-attached device.

A trailing edge of a control signal of a transistor controller for controlling an output transistor is detected by an edge detector of a clamp controlling circuit. A surge voltage from a back electromotive voltage induced in an inductance L1 is absorbed from the output transistor, only for a given period immediately after the solenoid is turned off, by turning a switching transistor into an on-state by a timer to force a clamping circuit into conduction. At a normal operation, since the clamping circuit is cut off from an output terminal, the clamping voltage can be set in a manner to reduce to a normal voltage in an IGN-line. Therefore, a peak power value of a power loss caused by the surge voltage at the output transistor can be reduced, whereby generation of heat at the output transistor can be reduced. Therefore, the chip size of the power IC can be reduced.

One or more aspects of the present invention relate to a transmission device having a digital predistortion unit which has a control input to which a control signal (CONT1) is applied. The control signal is output by a power control unit which evaluates a power control signal (LS). The predistortion unit distorts a baseband signal which is to be transmitted whenever the linearity of a power amplifier can no longer be observed at the currently required power without predistortion. To this end, the baseband signal is multiplied in complex fashion by a predistortion coefficient which is dependent on the level of the baseband signal.

A class AD audio amplifier system (10) with DC output detection logic (26) is disclosed. The amplifier system (10) includes multiple audio channels (20), each of which includes a pulse-width-modulator (PWM) (24). The DC detection logic (26) includes a sigma-delta modulator (60) and a digital low-pass filter (62) that monitors the PWM output signals from the PWM modulators (24). The sigma-delta modulator (60) operates at a first clock frequency, while the low-pass filter (62) operates at a much lower clock frequency, so that AC audio components, PWM harmonics, and sigma-delta quantization error is suppressed from the DC detection. The modulated filtered signal is compared against a threshold level (THRSH) to determine whether the amplitude of a DC component at the PWM output is sufficiently high to constitute a fault. If so, a fault detection signal (DC_DET) is issued, and the PWM modulators (24) are disabled to prevent unsafe conditions in the system (10).

An electronic part for a high frequency power amplifier is provided which is designed to constitute at least a part of a wireless communication system for performing feedback control by detecting an output power, and which can miniaturize a directional coupler. Also, the electronic part permits control of the output power with high accuracy without having any influence on a monitor voltage by a reflected wave propagating through a line of the directional coupler. The directional coupler includes a subline disposed in parallel to and in the vicinity of a part of a main line of an impedance matching circuit on the last output stage side of a power amplifier circuit, a capacitance element connected to between the main line and the subline, and a resistor element connected to between a constant potential point and a termination side of the subline. An output power detection circuit includes a first detection circuit for detecting an alternating current signal taken from a beginning side of the subline, a second detecting circuit for detecting an alternating current signal taken from a termination side of the subline, and a subtracting circuit for performing subtraction between an output of the first detection circuit and an output of the second detection circuit.

A monolithic 1.75 is mounted in a speaker cabinet 1.71 to drive the voice coil 1.74 of the speaker 1.70. The monolithic integrated circuit may be a class D amplifier 1.10, and is at least a half-bridge or full bridge power MOSFET device. Structures and process for forming the mos switching devices 2.20 of the bridge driver circuits are disclosed. Also disclosed is the N+ buried layer 4.14 of the QVDMOS transistors 4.43 of the bridge circuits.

Disclosed is an audio amplification circuit comprising: an input terminal for receipt of an audio input signal; a first preamplifier having an input operatively coupled to the input terminal and operable to provide a first amplified audio signal with a first signal amplification; a second preamplifier having an input operatively coupled to the input terminal and operable to provide a second amplified audio signal with a second signal amplification, smaller than the first signal amplification; a switch having a first input operatively coupled to the first preamplifier, a second input operatively coupled to the second preamplifier, and an output; an analogue-to-digital converter operatively coupled to the output of the switch and operable to provide a digital audio signal; a signal selection circuit operable to control the switch to selectively provide one of the first and second amplified audio signals on the output of the switch.

A method and apparatus provides techniques for electrically isolating switching devices in a stacked RF power amplifier, which prevents the switching devices from being subjected to high breakdown voltages. The isolation provided allows the power amplifier to be implemented on an integrated circuit.

Techniques for controlling one or more audio amplifiers in or associated with a device coupled on a local area network are disclosed. The device receives at least one selected source from other devices also coupled on the network According to one aspect of the techniques, an automatic shutdown control module is provided in the device to power down the audio amplifiers when there is no audio data flow coming to the device or power up the audio amplifiers when there is audio data flow coming to the device. In one embodiment, the procedure to power down or power up the amplifiers is in accordance with a hysteresis, wherein the hysteresis, being lagging of an effect behind its cause, protects the amplifiers and makes the powering-down or powering-up procedure unnoticeable to a user.

A method of estimating diaphragm excursion of an electrodynamic loudspeaker may be performed using audio signals. An audio output signal may be applied to a voice coil of the electrodynamic loudspeaker through an output amplifier to produce sound. A detected voice coil current and a determined voice coil voltage may be applied to a linear adaptive digital loudspeaker model that has a plurality of adaptive loudspeaker parameters. The parameter values of the adaptive loudspeaker parameters may be computed based on the linear adaptive digital loudspeaker model and applied to a non-linear state-space model of the electrodynamic loudspeaker. For the non-linear state-space model, a predetermined non-linear function may be applied to at least one of the plurality of received parameter values to compute at least one non-linearity compensated parameter value of the adaptive loudspeaker parameters, to determine an instantaneous excursion of the diaphragm.

A system for sensing the operating state of a tower top amplifier for mobile communication system, includes a plurality of tower top amplifiers each connected to communication antennas; and an operating state management part monitoring the operating state of each tower top amplifier. The operating state management part monitors the operating state of each tower top amplifier by the use of a single power supply line connected between itself and each tower top amplifier. In a method of sensing the operating state of a tower top amplifier for mobile communication system, the operating state of each tower top amplifier is monitored by using an amount of consumed DC power applied to the respective tower top amplifiers. This method includes the steps of measuring a potential difference of a given section of the DC power applied to each tower top amplifier; and comparing a result obtained by the measuring step and determining the normal or abnormal states of the tower top amplifiers.

A baseband signal predistortion processing device and method. Said device includes: a predistorter, for preserving and updating nonlinear filter parameter, carrying out power statistic of input signals, selecting corresponding nonlinear filter parameter according to the power statistical result and predistortion-processing baseband digital signals by use of said corresponding nonlinear filter parameter, and outputting the predistortion processed baseband digital signals; an adaptive parameter calculating unit, for calculating nonlinear filter parameter according to received feedback signals of radio-frequency channel and sampled signals of baseband digital signals, and transmitting the calculating result to the predistorter. Said method can not only solve the nonlinear problem of power amplifier, but also can select different non-linearity inverse model according to different input signal and power amplifier characteristic, and increase whole efficiency of base station transmitter.

A power supply including an inverter receiving a DC input signal from a DC input source (11). The inverter is implemented as a single-ended inverter. Each inverter is driven by a signal source (13A, 13B), which outputs an AC signal. The output from each inverter is input to a first stage harmonic filter. The power supply includes an output circuit that includes a rectifier (D1) arranged about a point so that if the inverter attempts to drive the point beyond a predetermined voltage, the rectifier conducts in order to return at least one of power and current to the DC input source. The output from the first harmonic filter (L1A, C1; L1B, C1) is output to a second harmonic filter (L2, C2) and is then output from the power supply.

Systems and methods for reducing the noise level in a multi-channel digital audio system by staggering the timing of the pulse-width modulation in the different channels and thereby reducing the magnitude and increasing the frequency characteristics of the generated switching noise. One embodiment comprises a multi-channel digital PWM amplifier in which the timing signals used by each channel's modulator are staggered to evenly space the switching edges of the generated PWM signals. An additional, complementary delay is implemented in each of the channels to equalize the total delay for each channel so that the outputs of the channels are synchronized. The different channels may be implemented on different chips, in which case the chips may be synchronized prior to staggering the signals processed in each of the channels.

A protection and attenuation circuit for sensitive AC loads is described. The circuit provides AC power protection and attenuation utilizing high-efficiency switch-mode techniques to attenuate an AC power signal by incorporating a bidirectional, transistorized switch driven from a pulse width modulation signal, PWM. The circuit monitors characteristics of the AC power signal driving a known load and characteristics of the load or other elements and determines the duty cycle of the pulse width modulated signal, PWM, based upon the duration and amplitude of the over-voltage, over-current, over-limit or other event.

While minimizing any increase in chip size and without incurring a loss in performance or operating characteristic under normal operating voltage conditions, a power amplifier protection circuit effectively prevents breakdown of power amplifying transistors resulting from output load fluctuations during operation with an overvoltage supply. The protection circuit includes a gate circuit electrically connected between the collector and base of at least the last-stage transistor in a power amplifier including transistors connected in stages. The gate circuit passes a feedback current to the base electrode of the protected transistor when a voltage exceeding a specific level is applied to the collector of the protected transistor.