A multimode envelope tracking (ET) circuit and related apparatus is provided. The multimode ET circuit is configured to provide an ET voltage(s) to an amplifier circuit(s) for amplifying a radio frequency (RF) signal(s) that may correspond to a wider range of modulation bandwidth. In this regard, the multimode ET circuit is configured to switch dynamically and opportunistically between different operation modes based on the modulation bandwidth of the RF signal(s). In examples discussed herein, the multimode ET circuit is configured to support a single amplifier circuit in a high-modulation-bandwidth mode and an additional amplifier circuit(s) in a mid-modulation-bandwidth mode and a low-modulation-bandwidth mode. By switching dynamically and opportunistically between different operation modes, it may be possible to reduce undesired series resonance that may cause distortion in the ET voltage(s), thus helping to improve efficiency and performance of the amplifier circuit(s) supported by the multimode ET circuit.

A circuit includes an input impedance, an operational amplifier, a voltage-adjusting circuit, a pulse-generating circuit, and a drive circuit. The input impedance is coupled to an input terminal of the operational amplifier, receives an input voltage, and outputs an input current. The operational amplifier is coupled to a first power voltage and outputs an amplified signal according to an input operating voltage and a feedback signal. The voltage-adjusting circuit adjusts the input operating voltage of the operational amplifier. The pulse-generating circuit generates a pulse width modulation signal according to the amplified signal. The drive circuit is coupled to a second power voltage and generates a driving signal according to the pulse width modulation signal. The feedback signal is correlated with the driving signal.

An inductor is provided, comprising: a first ferrite core piece and a second ferrite core piece, each of which are made of substantially similar materials, exhibit desired electromagnetic properties, and which are fashioned in a substantially similar manner and shape, and wherein each of the first and second ferrite core pieces comprises a substantially planar mating surface, a center post, and a wire core assembly channel, and wherein a first substantially planar mating surface of the first ferrite core piece is adapted to planarly mate with a second substantially planar mating surface of the second ferrite core piece; and a wire core assembly adapted to be substantially self-locating and self-centering about a first or second center post when located in a respective first or second wire core assembly channel.

An inductor is provided, comprising: a first ferrite core piece and a second ferrite core piece, each of which are made of substantially similar materials, exhibit desired electromagnetic properties, and which are fashioned in a substantially similar manner and shape, and wherein each of the first and second ferrite core pieces comprises a substantially planar mating surface, a center post, and a wire core assembly channel, and wherein a first substantially planar mating surface of the first ferrite core piece is adapted to planarly mate with a second substantially planar mating surface of the second ferrite core piece; and a wire core assembly adapted to be substantially self-locating and self-centering about a first or second center post when located in a respective first or second wire core assembly channel.

A one-to-many wireless speaker sound box device is disclosed, which is an integrally formed device and comprises an outer case, one or more diaphragm components, at lease two speaker bodies and at least one electric circuit board, wherein the electric circuit board includes a wireless transmission unit, a digital audio signal processing unit and at least two D-typed amplifier units, and the one-to-many wireless speaker sound box device is able to generate at least two or more sound channels, and each of the D-typed amplifier units is able to combine the left and right sound channel outputs in parallel into a single sound channel output and amplify the output audio signal in multiplication thereby driving the speaker bodies corresponding to different sound channels to operate, so that the issue “the higher the power is, the larger the magnification becomes, but the increased signal distortion ratio will also occur” typically found in the D-typed amplifier units can be resolved, and the effect of acoustic perception efficiency multiplication can be also achieved. Moreover, in addition to being applied to play music as a single one-to-many wireless speaker sound box device, two or more one-to-many wireless speaker sound box devices according to the present invention can be further connected in groups to play/receive audio signals thus generating the effects of music playing and karaoke singing entertainment.

A one-to-many wireless speaker sound box device is disclosed, which is an integrally formed device and comprises an outer case, one or more diaphragm components, at lease two speaker bodies and at least one electric circuit board, wherein the electric circuit board includes a wireless transmission unit, a digital audio signal processing unit and at least two D-typed amplifier units, and the one-to-many wireless speaker sound box device is able to generate at least two or more sound channels, and each of the D-typed amplifier units is able to combine the left and right sound channel outputs in parallel into a single sound channel output and amplify the output audio signal in multiplication thereby driving the speaker bodies corresponding to different sound channels to operate, so that the issue “the higher the power is, the larger the magnification becomes, but the increased signal distortion ratio will also occur” typically found in the D-typed amplifier units can be resolved, and the effect of acoustic perception efficiency multiplication can be also achieved. Moreover, in addition to being applied to play music as a single one-to-many wireless speaker sound box device, two or more one-to-many wireless speaker sound box devices according to the present invention can be further connected in groups to play/receive audio signals thus generating the effects of music playing and karaoke singing entertainment.

The present invention relates to a multi-level class D audio power amplifier for supplying an N-level drive signal to a loudspeaker. The multi-level class D audio power amplifier further comprises a switching matrix comprising a plurality of controllable semiconductor switches where the switching matrix comprising at least (N−2) switch inputs, coupled to respective ones of (N−2) DC input voltage nodes, and at least 2*(N−2) switch outputs coupled to respective ones of 2*(N−2) intermediate nodes of a first output driver. A control circuit is configured to sequentially connect each of the (N−2) DC input voltages to a predetermined set of nodes of the 2*(N−2) intermediate nodes of the first output driver via the switching matrix in accordance with one or more of the 2*(N−1) modulated control signals of the first output driver. N is a positive integer larger than or equal to 3.

A class-D amplifier includes an analog-to-digital converter (ADC) configured to generate a first digital signal based on an analog input signal and a feedback signal received at an input node. A loop filter is configured to modify the first digital signal by moving an error of the ADC out of a predetermined frequency band, and a compensation filter is configured to further modify the first digital signal by introducing one or more poles or zeros, thereby generating a second digital signal. An output circuit is configured to generate an output signal at an output node based on the second digital signal, and the feedback signal is generated from the output signal.

An embodiment apparatus comprises a switching-type output power stage, a modulator circuit configured for carrying out a pulse-width modulation and converting an electrical input signal into an input signal pulsed between two electrical levels, having a mean value proportional to the amplitude of the input signal, and a circuit arrangement for controlling saturation of an output signal supplied by the switching-type output power stage. The circuit arrangement comprises a pulse-remodulator circuit, between the output of the modulator circuit and the input of the switching-type output power stage, that is configured for supplying, as a driving signal to the switching-type output power stage, a respective modulated signal pulsed between two electrical levels, measuring a pulse width as pulse time interval elapsing between two consecutive pulsed-signal edges of the pulsed input signal, and, if the measurement indicates that the latter is below a given minimum value, remodulating the pulsed input signal.

An embodiment apparatus comprises a switching-type output power stage, a modulator circuit configured for carrying out a pulse-width modulation and converting an electrical input signal into an input signal pulsed between two electrical levels, having a mean value proportional to the amplitude of the input signal, and a circuit arrangement for controlling saturation of an output signal supplied by the switching-type output power stage. The circuit arrangement comprises a pulse-remodulator circuit, between the output of the modulator circuit and the input of the switching-type output power stage, that is configured for supplying, as a driving signal to the switching-type output power stage, a respective modulated signal pulsed between two electrical levels, measuring a pulse width as pulse time interval elapsing between two consecutive pulsed-signal edges of the pulsed input signal, and, if the measurement indicates that the latter is below a given minimum value, remodulating the pulsed input signal.