Systems and methods for amplifying an RF input signal include employing a moderately power efficient wide bandwidth device, such as an AB-type amplifier, to amplify the power residing in the high frequency components of the input signal, and a highly power efficient narrow bandwidth device, such as a synchronous buck DC/DC converter, to amplify the power residing in the low frequency components of the input signal. The amplified low frequency components and high frequency components are then combined to produce an amplified replica of the RF input signal. A positive feedback loop is provided between the output of the AB-type amplifier and the input of the DC/DC converter to provide stability to the amplified RF signal. A negative feedback loop is provided between the output of the DC/DC converter and the input of the AB-type amplifier to minimize interference introduced by the DC/DC converter.

Apparatus and method for efficiently amplifying wideband envelope signals

A method and apparatus for efficient power amplification over a wide dynamic range and for a number of modulation formats includes a carrier amplifier (30) and a peaking amplifier (40). The carrier amplifier (30) operates with a bias generated by an envelope amplifier (80) which amplifies the envelope of an input signal as generated by an envelope detector (70). The peaking amplifier (40) operates with a fixed bias. The outputs of the carrier amplifier (30) and the peaking amplifier (40) are combined using an impedance transforming network (50). Envelope amplifier (80) can be turned on for high efficiency low power level operation, or it can be turned off for standard Doherty-type operation.

Method and apparatus for high efficiency power amplification

A power supply system comprises a low-speed power supply and a high-speed power supply configured to operate in first and second frequency ranges, respectively, and generate first and second outputs, respectively. The lower end of the second frequency range is at least higher than a lower end of the first frequency range. A frequency blocking power combiner circuit combines the power from the first output with the power from the second output to generate a combined, third output for driving a load, while providing frequency-selective isolation between the first and second outputs. A feedback circuit is coupled to receive the combined, third output through a global feedback loop. The feedback circuit generates first and second power supply control signals for controlling the low-speed power supply and the high-speed power supply, respectively, based on a difference between the third output and the predetermined control signal.

Power combining power supply system

An envelope tracking radio frequency (RF) power amplifier having an adaptive envelope signal processing circuit is disclosed. An RF input voltage is sampled by the adaptive envelope signal processing circuit which provides control signals to the power supply which supplies voltages to RF power devices in order to simultaneously satisfy two operating conditions: a) provide best possible efficiency of the power amplifier stages depending on the input signal characteristics and b) provide compensation for RF transistor AM-AM and AM-PM distortion compensation across the power range. In particular, the voltage control provides for constant power amplifier gain across the input signal dynamic range, thus minimizing power amplifier amplitude distortions and extending the useful power amplifier linear dynamic range up to saturation point. The power amplifier thus exhibits better linearity and efficiency than offered by conventional techniques and topologies.

Constant gain nonlinear envelope tracking high efficiency linear amplifier

A class D amplifier utilizing first and second switches (22, 24) connected in series to conduct current from a common source in a sequential manner. The switches have a common output note between them. A pulse width modulator (16) is utilized to produce first and second signals (70, 76) identified as the high and low side. The first switch connects to a drive which receives the first signal from the pulse width modulator to close the first switch. A second switch drive receives a second signal from the pulse width modulator to operate the second switch in a sequential manner. A toggle or commutator device utilizes third and fourth switches (44, 46) in series with an inductor. The toggle device is connected to the common node between the first and second swithces in order to closely control the switching of the first and second switches to eliminate loss of energy associated with the rapid switching normally found in a class D amplifier.

Class D amplifier with switching control

A multi-channel audio power amplifier is arranged to amplify, by an analog amplifying circuit, high frequency range components of an audio signal and to amplify low frequency range components of said signal by a class D amplifying circuit, to thereby enhance the power efficiency of the amplifier. The carrier frequency of the class D amplifying circuit is set lower than that employed conventionally, to eliminate spurious radiation of the carrier signal.

Kenji Yokoyama

Papers

Multi-channel audio power amplifier