A tracker circuit configured to provide a variable supply voltage to a power amplifier (PA) circuit is disclosed. The tracker circuit includes a state machine circuit comprising a plurality of states mapped in accordance with transitions associated with a mapping scheme. In some embodiments, the plurality of states of the state machine circuit identify one or more operational modes associated with the tracker circuit, wherein at least one operational mode comprises one or more voltage levels respectively associated therewith. In some embodiments, the one or more operational modes includes at least two active operational modes. In some embodiments, a transition between the one or more operational modes of the tracker circuit is controlled by a digital selection signal received from a digital communication interface associated therewith.

A DC-DC converter and a corresponding method for maintaining an output voltage of the DC-DC converter, wherein the DC-DC converter is configured to operate in a discontinuous conduction mode, within a predetermined voltage range. The method comprises adjusting a duty cycle of the DC-DC converter based on the output voltage to maintain the output voltage within a predetermined voltage range; wherein the duty cycle of the DC-DC converter is adjusted by switching between a first switching frequency to a second switching frequency, and the first switching frequency and the second switching frequency are selected such that the first switching frequency and the second switching frequency fall outside of at least one predefined disallowed frequency band.

Disclosed are systems, devices, modules, methods, and other implementations, including a method for digital predistortion that includes receiving, by a digital predistorter, a first signal that depends on amplitude variations based on an input signal, u, with the variations of the first signal corresponding to time variations in non-linear characteristics of a transmit chain that includes a power amplifier. The method further includes receiving, by the digital predistorter, the input signal u, generating, by the digital predistorter, based at least in part on signals comprising the input signal u and the first signal, a digitally predistorted signal v to mitigate the non-linear behavior of the transmit chain, and providing the predistorted signal v to the transmit chain.

A multi-mode envelope tracking (ET) target voltage circuit is provided. In an ET amplifier apparatus, an amplifier circuit is configured to amplify a radio frequency (RF) signal based on a time-variant ET voltage, which is generated based on a time-variant ET target voltage configured to track a time-variant power envelope of the RF signal. Notably, when the ET amplifier apparatus operates in a fifth-generation (5G) standalone (SA) or non-standalone (NSA) mode, the amplifier circuit may experience interference creating a reverse intermodulation product (rIMD) that can degrade efficiency and performance of the amplifier circuit. In examples discussed herein, the multi-mode ET target voltage circuit is configured to generate the ET target voltage based on a reduced slew rate to help suppress the rIMD at the amplifier circuit, thus making it possible to improve efficiency and performance of the ET amplifier apparatus in the SA and the NSA modes.

An envelope tracking (ET) radio frequency (RF) front-end circuit receives a single tracking signal (e.g., Vramp) from a baseband transceiver and generates a plurality of control signals (Vcc). The control signals are created by a multiple control signal generator circuit based on a calculated load estimate for each relevant power amplifier. The load estimate may be calculated from a sensed current and voltage. By providing control signals optimized for loads presented to the power amplifiers, the overall efficiency of the transmitter is improved.

The present invention discloses a loudspeaker system and an electronics device. The loudspeaker system comprises: a power amplifier, which amplifies an input audio signal; a transducer, connected to the power amplifier, which receives the amplified input audio signal and converts it into a sound wave; a power supply, which provides current to the power amplifier; and a secondary battery, wherein the secondary battery provides extra current to the power amplifier when the power amplifier needs a higher current to actuate the transducer.

A switching regulator configured to generate an output voltage based on an input voltage is provided. The switching regulator includes: an inductor; and a capacitor circuit configured to generate the output voltage by charging an inductor current passing through the inductor from the input voltage, provide a first capacitance as a load capacitance based on the output voltage being a first level or a second level, and provide a second capacitance, which is less than the first capacitance, as the load capacitance based on the output voltage being between the first level to the second level.

A system may include a charge pump configured to boost an input voltage of the charge pump to an output voltage greater than the input voltage, a current mode control loop for current mode control of a power amplifier powered by the output voltage of the charge pump, and a controller configured to, in a current-limiting mode of the controller, control an output power of the charge pump to ensure that an input current of the charge pump is maintained below a current limit, control the power amplifier by placing the power amplifier into a high-impedance mode during the current-limiting mode, and control state variables of a loop filter of the current mode control loop during the current-limiting mode.

Apparatus and methods for envelope tracking systems with automatic mode selection are provided herein. In certain configurations, a power amplifier system includes a power amplifier configured to provide amplification to a radio frequency signal and to receive power from a power amplifier supply voltage, and an envelope tracker including a signal bandwidth detection circuit configured to generate a detected bandwidth signal based on processing an envelope signal corresponding to an envelope of the radio frequency signal. The envelope tracker further includes a switch bank configured to receive a plurality of regulated voltages, a filter configured to filter an output of the switch bank to generate the power amplifier supply voltage, and a mode control circuit configured to control a filtering characteristic of the filter based on the detected bandwidth signal.

A driver circuit is provided. The driver circuit includes a first operational amplifier circuit, a second operational amplifier circuit, and at least one power switching circuit is provided. The first operational amplifier circuit receives a first input signal and generates a first output signal according to the first input signal. The second operational amplifier circuit receives a second input signal and generates a second output signal according to the second input signal. The at least one power switching circuit is configured to be coupled to switch a first input stage circuit to one of a first output stage circuit and a second output stage circuit, and the at least one power switching circuit is further coupled to switch a second input stage circuit to the other one of the first output stage circuit and the second output stage circuit.