A speaker, a television provided with the speaker and a multimedia device are provided. The speaker includes a box body and a plurality of transducer units installed within the box body by means of parallel connection: front sound cavities of the plurality of transducer units are independent of each other, respectively; and the plurality of transducer units share one back sound cavity. The speaker possesses such advantages that it has a high sound pressure level output and a smaller power consumption, it is usable to reduce the back-cavity acoustic resistance, and it is usable to raise the lower frequency limit in the low frequency range.

A supply modulator, a modulated power supply circuit, and associated control method are provided. The modulated power supply circuit includes the supply modulator and a DC-DC voltage converter, and the supply modulator includes a linear amplifier and a switching converter. The linear amplifier generates an AC component of a modulated voltage according to a regulated voltage and an envelope tracking signal. The supply voltage is converted to the regulated voltage by the DC-DC voltage converter, and the regulated voltage is greater than or less than the supply voltage. The switching converter includes a step-down circuit and a path selection circuit. The path selection circuit selects one of the supply voltage and the regulated voltage as a DC input voltage. The step-down circuit converts the DC input voltage to a DC component of the modulated voltage which is less than the DC input voltage.

A Doherty amplifier module includes first and second amplifier die. The first amplifier die includes one or more first power transistors configured to amplify, along a first signal path, a first input RF signal to produce an amplified first RF signal. The second amplifier die includes one or more second power transistors configured to amplify, along a second signal path, a second input RF signal to produce an amplified second RF signal. A phase shift and impedance inversion element is coupled between the outputs of the first and second amplifier die. A shunt inductance circuit is coupled to the output of either or both of the first and/or second amplifier die. Each shunt inductance circuit at least partially resonates out the output capacitance of the amplifier die to which it is connected to enable the electrical length of the phase shift and impedance inversion element to be increased.

An embodiment of a Doherty amplifier module includes a substrate, a first amplifier die, and a second amplifier die. The first amplifier die includes one or more first power transistors configured to amplify, along a first signal path, a first input RF signal to produce an amplified first RF signal. The second amplifier die includes one or more second power transistors configured to amplify, along a second signal path, a second input RF signal to produce an amplified second RF signal. The first and second amplifier die each also include an elongated output pad that is configured to enable a pluralities of wirebonds to be connected in parallel along the length of the elongated output pad so that the pluralities of wirebonds extend in perpendicular directions to the first and second signal paths.

A preamplifier system to adjust the level of an audio signal, said system comprising a transient adjustment line and a steady adjustment line, each receiving the input of the preamplifier system, each adjustment line having an input and an output, said system further comprising a setting device to produce a setting adjustment value, a controller to receive the setting adjustment value and to control the transient adjustment line and the steady adjustment line, a switching module connected an output of the preamplifier system and to the output of the transient adjustment line and output of the steady adjustment line, the transient adjustment line being made of semiconductors and the steady adjustment line being made of a coil with multiple selectable windings.

A transmission apparatus including: a branch circuit that branches a signal including first data and second data superimposed on the first data into two signals; a limiting amplifier that amplifies one signal in the two signals; a linear amplifier that amplifies another signal in the two signals; a first detector that detects the first data from the amplified one signal; and a second detector that detects the second data from the amplified another signal and the amplified one signal.

An efficient power supply with fast, wideband response has been disclosed. In one implementation, two switching regulators with different frequency responses are combined to provide wideband, efficient power.

The disclosed technology includes device, systems, techniques, and methods for amplifying a complex modulated signal with a mixed-signal power amplifier. A mixed-signal power amplifier may include an input network for splitting an input signal to multiple signals with corresponding phase and amplitude offsets, a main power amplification path including at least an analog power amplifier for amplifying a first signal, one or more auxiliary power amplification paths including at least one digitally controlled analog power amplifier in each path for amplifying a second signal, and an output network for combining the two amplified signals. The main power amplification path and the auxiliary power amplification paths can operate together to achieve load modulation to enhance the overall power amplifier efficiency at power back-off mode and the overall power amplifier linearity. The disclosed technology further includes transmission systems incorporating the mixed-signal power amplifier.

A preamplifier system to adjust the level of an audio signal, said system comprising a transient adjustment line and a steady adjustment line, each receiving the input of the preamplifier system, each adjustment line having an input and an output, said system further comprising a setting device to produce a setting adjustment value, a controller to receive the setting adjustment value and to control the transient adjustment line and the steady adjustment line, a switching module connected an output of the preamplifier system and to the output of the transient adjustment line and output of the steady adjustment line, the transient adjustment line being made of semiconductors and the steady adjustment line being made of a coil with multiple selectable windings.

Envelope trackers providing compensation for power amplifier output load variation are provided herein. In certain configurations, a radio frequency (RF) system includes a power amplifier that amplifies an RF signal, an output detector coupled to an output of the power amplifier and that generates an output detection signal, an input detector coupled to an input of the power amplifier and that generates an input detection signal, and an envelope tracker that generates a power amplifier supply voltage for the power amplifier based on an envelope of the RF signal. The envelope tracker compensates the power amplifier for output load variation based on the output detection signal and the input detection signal.