The present invention provides high power linear amplification of an amplitude and/or phase modulated signal using multiple saturated (or if desired, unsaturated) amplifiers (4) driven by an appropriate set of switched (5), and/or phase modulated (6) constant amplitude signals derived from the input signal. The present invention combines three amplitude reconstruction techniques and implements the amplitude reconstruction modulator (11) digitally.

Amplification using amplitude reconstruction of amplitude and/or angle modulated carrier

A signal of varying amplitude in a first saturated power amplifier that operates from a fixed voltage power supply to produce a first output signal of constant amplitude. The signal of varying amplitude also is amplified in a second saturated power amplifier that operates from a modulated voltage power supply, to produce a second output signal of amplitude that depends on the signal of varying amplitude, a modulated power supply voltage, and on an invert/noninvert control signal. The first and second output signals are combined into a load. The modulated voltage power supply is modulated while generating the invert/noninvert control signal, such that the combined first and second output signals into the load amplify the signal of varying amplitude. The signal of varying amplitude also may be of varying amplitude and varying phase.

Amplification systems and methods using fixed and modulated power supply voltages and buck-boost control

An antenna switch diversity algorithm, and systems and methods to provide antenna diversity by implementing the algorithm in, for example, an IEEE 802.11a compliant environment, are presented. In accordance with the algorithm, one antenna of at least two antennas is designated as a default antenna at a communications device that sends and receives transmit and receive packets. The default antenna designation is changed depending on long-term and short-term learning processes implemented in, for example, software and hardware. The long-term and short-term learning processes analyze packet transmission and reception results of the antennas. The antenna switch diversity algorithm is applicable to multiple antennas.

Method and system for providing antenna diversity

Two amplifiers that are driven using outphasing modulation are coupled to one another so that the amplifiers affect each other's effective load line. The two amplifiers can maintain efficiency over a wider dynamic range than in a conventional amplifier. Amplifiers according to the invention amplify an AC input signal of varying amplitude and varying phase using a DC power supply. A converter converts the AC input signal into a first signal having constant amplitude and a first phase angle and into a second signal having constant amplitude and a second phase angle. The first amplifier amplifies the first signal, and the second amplifier amplifies the second signal. A coupler couples the first and second amplifiers to one another and to a load impedance, such that voltages or currents in the first amplifier become linearly related to voltages or currents in the second amplifier. The coupler may include at least one transformer that serially couples the first and second amplifiers to one another and to the load impedance. The coupler may also include first and second quarter wave transmission lines that couple the first and second amplifiers to one another and to the load impedance. The amplifiers preferably use bilateral devices, such that current flows from the first and second amplifiers to the DC power supply during part of a signal cycle, and thereby returns energy to the DC power supply.

Hybrid Chireix/Doherty amplifiers and methods

A LINC amplifier of a radio frequency transmitter provides substantially linear amplification from two nonlinear amplifiers by decomposing the original signal into two constant amplitude envelope, phase varying signals, which, when combined, constructively and destructively interfere to re-form the original signal. The output of the LINC amplifier, which is to be transmitted via an antenna, is an amplified form of the original signal. The LINC amplifier uses a digital control mechanism to control and adapt a digital compensation network that directly compensates for the imperfections of the analog RF environment, including the amplifiers. The mechanism monitors the combined amplifier output and adjusts the signal components in order to precisely compensate for any differences in the characteristics of the separate signal paths which would cause the combination not to accurately represent the original signal. The mechanism also corrects the component signals using information which can be applied to the amplifiers independent of the signal to be transmitted.

Use of antiphase signals for predistortion training within an amplifier system

A linear amplification providing a replica of an input signal having amplitude variations is accomplished at frequencies and power levels for which linear gain elements are not available. Linear amplification is provided by separating an original bandpass input signal into two components, one of which is a constant amplitude sinusoidal component and the other of which is a low-pass envelope signal. The envelope signal is processed to produce both an inverse sine, phase modulated signal and the complex conjugate of the modulated signal. The phase variations of the modulated signal and of its complex conjugate are proportional to the inverse sine of the envelope. The modulated signal and its complex conjugate are each separately mixed with the constant amplitude sinusoidal signal to produce two constant amplitude signals which are filtered and amplified by either linear or nonlinear devices. The amplified filtered resultants are combined to produce a linearly amplified replica of the original bandpass input signal.

Linear amplification using nonlinear devices and inverse sine phase modulation

A mobile radio system having a plurality of base station transmitting antennas for each channel. When the mobile receiver encounters a fading signal level from the antenna then in use, it transmits an out of message band signal back to the base station which commands the base to switch to a different antenna thus providing diversity on the base to mobile link. Particular circuits are provided to discriminate between rapid Rayleigh fades and slow shadowing fades and to transmit a command for an antenna switch based on the Rayleigh fades.

Rustako Jr Anthony Joseph

Papers

Linear amplification using nonlinear devices and inverse sine phase modulation

Diversity system for mobile radio using fade rate switching