Aspects of the disclosure relate to a radio frequency phase shifter. An example includes an amplification stage to produce an amplified voltage, the amplification stage having a first amplifier with a first input coupled to a first output of a hybrid coupler and a second amplifier with a complementary second input coupled to a complementary second output of the hybrid coupler. A vector modulation stage coupled to the amplification stage receives the amplified voltage and produces a modulated vector, the vector modulation stage has an in-phase section and a quadrature section to control the phase of the modulated vector in response to a phase control signal. A varactor coupled across the first input and the second input of the amplification stage adjusts the capacitance between the first input and the second input in response to a capacitance control signal.

This application is generally related to methods for improving performance in a system. One of the methods may include a step of determining whether absorbed power in a system meets a predetermined threshold. The absorbed power may be based upon first and second Walsh codes transmitted to each of first and second gain and phase modulators in the system. The first Walsh code may be orthogonal to the second Walsh code. A first set of the first and second Walsh codes may be inverted with respect to a second set of the first and second Walsh codes. The method may also include a step of modulating the absorbed power in view of the determination. The method may further include a step of transmitting feedback based upon the modulated power to the first and second gain and phase modulators.

Systems and methods for a tunable impedance are provided. A tunable impedance includes a transistor assembly having two terminals and a control input. The transistor assembly includes one or more transistors electrically connected between the two terminals to provide a first impedance between the two terminals, based upon a control signal. One or more replica transistors react to the control signal in a similar fashion as the transistor assembly, to provide a replica impedance based upon the control signal. A control circuit is configured to generate the control signal based upon a voltage across the replica transistor(s) and/or a current through the replica transistor(s).

Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes an error amplifier that controls a voltage level of a power amplifier supply voltage of the power amplifier based on amplifying a difference between a reference signal and an envelope signal indicating an envelope of the RF signal. The envelope tracker further includes a multi-level switching circuit that generates an error amplifier supply voltage based on sensing a current of the error amplifier, and uses the error amplifier supply voltage to power the error amplifier.

A radio frequency (RF) transmitter includes a radiating element, a chip and a phase shifting circuit. The radiating element is arranged to receive a plurality of electrical signals to produce an RF output signal. The chip includes an amplifier circuit. The amplifier circuit is configured to amplify an RF input signal to generate a plurality of amplified signals at a plurality of output terminals, respectively. The phase shifting circuit is located outside the chip, and coupled to the output terminals and the radiating element. The phase shifting circuit is arranged to phase shift the amplified signals, and accordingly generate the electrical signals fed to the radiating element. The phase shifting circuit and the radiating element are formed on a same substrate.

Disclosed is a reconfigurable power amplifier having a 2.sup.N−1 number of input-side reconfigurable quadrature couplers connected in a tree structure, wherein a 2.sup.(N−1) number of the input-side reconfigurable quadrature couplers have coupler output terminals, and a root of the tree structure is one of the input-side reconfigurable quadrature couplers having a main input terminal. Also included is a 2.sup.N−1 number of output-side reconfigurable quadrature couplers connected in a tree structure, wherein a 2.sup.(N−1) number of the output-side reconfigurable quadrature couplers have coupler input terminals, and a root of the tree structure is one of the output-side reconfigurable quadrature couplers having a main output terminal. Further included is a 2.sup.N number of constituent amplifiers divided into amplifier pairs having amplifier input terminals connected to corresponding ones of the coupler output terminals and having amplifier output terminals coupled to corresponding ones of the coupler input terminals.

A signal coupling system may include a directional coupler that includes a first conductor and a second conductor. The first conductor may include a first end and a second end and may be generally arranged along a first plane. The second conductor may include a third end and a fourth end and may generally be arranged as a plurality of windings along a second plane. The signal coupling system may also include a transceiver, electrically conductively conducted to the first end; and an antenna, electrically conductively conducted to the second end. The second conductor may be configured to generate a coupling with the first conductor when the first conductor conducts an electric signal, such that the coupler conducts a first electrical signal from the first end to the second end at a second power, and conducts the electrical signal via the coupling to the third end at a third power.

A radio frequency front-end is disclosed having a first power amplifier (PA) having a first PA input and a first PA output, a second PA having a second PA input and a second PA output, and a low-noise amplifier (LNA) having an LNA output connected to a receive output terminal and an LNA input. An input 90° hybrid coupler has a first port input connected to a transmit terminal, a second port input connected to a fixed voltage node through an isolation impedance, a third port output connected to the first amplifier input and a fourth port output connected to the second amplifier input. An output 90° hybrid coupler has a first port output connected to a common terminal, a second port output connected to the LNA input, a third port input connected to the second PA output, and a fourth port input connected to the first PA output.

An RF amplifier utilizes first and second main amplifiers in a balanced amplifier configuration with first and second auxiliary amplifiers connected in parallel across the first and second main amplifiers, respectively. The main and the auxiliary amplifiers are biased such that the third-order nonlinearity components in the combined output current are reduced. A common or independent bias control circuit(s) control(s) the DC operating bias of the auxiliary amplifiers and establishes DC operating points on curves representing third-order nonlinear components within the drain current having a positive slope (opposite to the corresponding slope of the main amplifiers). This results in reduction of overall third-order nonlinear components in combined currents at the output. In another embodiment, a phase shift of an input to one auxiliary amplifier is used to provide a peak in minimization at a frequency associated with the phase shift.

Systems and apparatuses are disclosed that include an RF generator configured to generate RF signals having a wavelength. Amplifiers are configured to receive and amplify the RF signals from the RF generator and are separated from each other by a separation distance in a range between about 0.2 times the wavelength and about 10.0 times the wavelength. A power management system is configured to control one or more of the amplifiers based on information received that is associated with the RF signals.