A delay-compensating power management circuit is provided. The power management circuit includes a power management integrated circuit (PMIC) configured to generate a time-variant voltage(s) based on a time-variant target voltage(s) for amplifying an analog signal(s) associated with a time-variant power envelope(s). A voltage processing circuit is provided in the power management circuit to determine a temporal offset, which can be positive or negative, between the time-variant power envelope(s) and the time-variant target voltage(s). Accordingly, the voltage processing circuit modifies the time-variant target voltage(s) to substantially reduce the determined temporal offset and thereby realign the time-variant target voltage(s) with the time-variant power envelope(s). By realigning the time variant target voltage(s) with the time-variant power envelope(s), it is possible to align the time-variant voltage(s) with the time-variant power envelope(s) to reduce distortions (e.g., amplitude clipping) during amplification of the analog signal.

An audio signal amplification device includes: a clock generation circuit that generates a clock for use in amplifying an audio signal; and a power supply circuit that generates direct current power, which is supplied to the clock generation circuit, from input power. The power supply circuit includes: a constant voltage generation circuit that generates direct current power of a constant voltage from the input power; a first capacitor; a first charging circuit that charges the first capacitor by using the input power; and a selection circuit. The selection circuit selects one direct current power of the direct current power generated in the constant voltage generation circuit and of direct current power charged to the first capacitor, and supplies the selected direct current power to the clock generation circuit.

A power amplifying circuit includes a switching circuit, an amplifier and a load. The switching circuit receives a first supply voltage and a second supply voltage. When the switching circuit is in a first operation mode, the first supply voltage is provided to a node. When the switching circuit is in a second operation mode, the second supply voltage is provided to the node. The amplifier receives a first input signal and a second input signal, and outputs a first output signal and a second output signal from a first output terminal and a second output signal, respectively. The load includes a first inductor and a second inductor. The first inductor is connected between the node and the first output terminal. The second inductor is connected between the node and the second output terminal.

A multi-voltage generation circuit and related envelope tracking (ET) amplifier apparatus is provided. In one aspect, a multi-voltage generation circuit is configured to generate a number of ET target voltages based on an analog voltage signal. In another aspect, a multi-amplifier ET circuit can be configured to include a number of amplifier circuits for amplifying concurrently a radio frequency (RF) signal based on a number of ET voltages. The multi-amplifier ET circuit also includes a number of driver circuits configured to generate the ET voltages base on a number of ET target voltages. In this regard, the multi-voltage generation circuit can be provided in the multi-amplifier ET circuit to generate the ET target voltages based on the analog voltage signal that corresponds to the RF signal. In examples discussed herein, the driver circuits are co-located with the amplifier circuits to help improve efficiency and maintain linearity in the amplifier circuits.

According to an embodiment, a method of operating an acoustic device includes buffering, by a buffer circuit, a first electrical signal from an acoustic transducer to produce a second electrical signal, receiving a feedback signal at a supply circuit, and comparing the feedback signal to a first threshold. The feedback signal is based on the first electrical signal. The method further includes, based on comparing the feedback signal to the first threshold, switching between a first mode and a second mode, supplying a first supply voltage to the buffer circuit during the first mode, and supplying a second supply voltage to the buffer circuit during the second mode. The first supply voltage is different from the second supply voltage.

Described embodiments provide a radio frequency (RF) amplifier system having at least one amplifier. The at least one amplifier includes an RF input port, an RF output port and a drain bias port. At least one voltage modulator is coupled to the bias port of the least one amplifier to provide a bias voltage. The bias voltage is selected by switching among a plurality of discrete voltages. At least one filter circuit is coupled between the at least one voltage modulator and the at least one amplifier. The at least one filter circuit controls spectral components resultant from transitions in the bias voltage when switching among the plurality of discrete voltages. A controller dynamically adapts at least one setting of the at least one voltage modulator by using multi-pulse transitions when switching among the plurality of discrete voltages for a first operating condition of the RF amplifier.

A power amplifier includes a power switching circuit, a driver circuit, and an amplifier circuit. The power switching circuit is configured to receive a first voltage and a second voltage, and provide the first voltage or the second voltage according to an operation mode of the power amplifier. The driver circuit is coupled to the power switching circuit. The driver circuit is configured to operate according to the first voltage or the second voltage and generate a driving signal according to an input signal. The amplifier circuit is coupled to the power switching circuit and the driver circuit. The amplifier circuit is configured to operate according to the first voltage or the second voltage and generate an output signal according to the driving signal.

Methods and systems for power amplification with digital quantized power supply with multiple amplifiers are disclosed herein. In one embodiment, In one embodiment, a time-varying envelope signal is sampled, quantized and decomposed into several constituent signals that are individually amplified, and then combined to form a desired amplified version of the quantized time-varying envelope. Amplitude, phase and/or frequency characteristics of one or more of the signals and supply voltages V.sub.dd and source current of one or more amplifiers are digital controlled based on the information provided by quantization process and slow and fast power control information. Amplitude, phase and/or frequency characteristics of one or more of the constituent signals to be amplified are controlled to provide the desired amplitude, phase, frequency, and/or spectral characteristics of the desired quantized version of the time-varying envelope signal.

A multi-channel RF transmit system (1) especially for use in a magnetic resonance examination system comprising, a plurality of RF channels (18, 19) wherein each of the RF channels (18, 19) has an RF amplifier. The multi-channel RF transmit system (1) further comprises a power supply device (2) configured to supply power to the amplifiers (4, 5), a first capacitor bank (6), wherein the first capacitor bank (6) is connected to the power supply device (2) and connected to a first RF amplifier (4), a second capacitor bank (7), wherein the second capacitor bank (7) is connected to the power supply device (2) and connected to a second RF amplifier (5) and a third capacitor bank (8) also connected to the power supply device (2). The third capacitor bank (8) is connected to a DC switch (9), wherein the DC switch (9) is configured to switch the power supplied by the third capacitor bank (8) to the first amplifier (4) or the second amplifier (5). Therefore, a multi-channel RF transmit system (1) is disclosed where parts of the total available capabilities of discrete stored energy can be directed to one or the other RF amplifier channel (18, 19) leading to a more effective and cost saving design of the DC power supply chain.

A first branch group circuit includes a first branch circuit receiving a first RF input signal and first control information; and a second branch circuit receiving the first input signal and second control information. Each of the first and second branch circuits includes a power amplifier. The second control information enables the second branch circuit to be switched on or off while the first branch circuit remains on. A second branch group circuit includes: a third branch circuit receiving a second RF input signal and third control information; and a fourth branch circuit receiving the second input signal and fourth control information. Each of the third and fourth branch circuits includes a power amplifier. The fourth control information enables the fourth branch circuit to be switched on or off while the third branch circuit remains on. A combiner combines output signals of the power amplifiers to produce an output signal.