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.

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.

Methods and apparatus are provided. In an example aspect, a method of operating an amplifier circuit is provided. The amplifier circuit comprises a first amplifier configured to receive a first signal, a balanced amplifier comprising second and third amplifiers and configured to receive a second signal, and a first directional coupler. An output of the first amplifier is connected to a transmitted port of the first directional coupler, an output of the second amplifier is connected to an input port of the first directional coupler, an output of the third amplifier is connected to an isolated port of the first directional coupler, and a coupled port of the first directional coupler is connected to an output of the amplifier circuit. The method comprises operating the amplifier circuit in a first output peak amplitude range of the amplifier circuit wherein, in the first output peak amplitude range, the first signal is based on a signal to be amplified and has an amplitude that increases across the first output peak amplitude range from substantially zero to a first amplitude, and the second signal is substantially zero, and operating the amplifier circuit in a second output peak amplitude range of the amplifier circuit, wherein the second output peak amplitude range is higher than the first output peak amplitude range and wherein, in the second output peak amplitude range, the first signal is based on the signal to be amplified and has an amplitude that decreases across the second output peak amplitude range from the first amplitude to a second amplitude, and the second signal is based on the signal to be amplified and has an amplitude that increases across the second output peak amplitude range from a third amplitude to a fourth amplitude.

A load modulation amplifier is disclosed having a first amplifier and a second amplifier. An input quadrature coupler and an output quadrature coupler are coupled between the first amplifier and the second amplifier. A splitter has a first splitter output, a splitter input coupled to a signal input, and a second splitter output coupled to a second port of the input quadrature coupler, and a variable attenuator is coupled between the first splitter output and a first port of the input quadrature coupler. An attenuation controller has a controller output that is coupled to an attenuation control input of the variable attenuator, wherein the attenuation controller autonomously generates a control signal in response to a power sample signal in proportion to a radio frequency signal received at the radio frequency signal input.

There is provided a quasi-circulator. The quasi-circulator includes: a first coupler having an input end connected to a transmission end; a first amplifier having an input end connected to an output end of the first coupler; a second amplifier having an input end connected to the output end of the first coupler; a second coupler having one end connected to an output end of the first amplifier and an output end of the second amplifier, and the other end connected to an antenna; and a third coupler having one end connected to the output end of the first amplifier and the output end of the second amplifier, and the other end connected to a reception end. Accordingly, a loss occurring at the quasi-circulator is minimized, and eventually, efficiency of an RF FEM employed in an ultrahigh frequency radar system is enhanced.

Circuits and methods for achieving good amplifier AM-AM and AM-PM metrics while achieving good power, PAE, linearity, and EVM performance. Embodiments compensate for a non-linear distortion profile (e.g., an AM-PM and/or AM-AM profile) in an amplifier by pre-processing an input signal, such as a radio-frequency signal, to alter the non-linear distortion profile of the input signal so as to compensate for the non-linear distortion profile imposed by a coupled device, such as an amplifier. An inventive aspect includes linearizing an output from an amplifier having a first non-linear distortion profile, including passing an input signal having a second non-linear distortion profile through a reflective hybrid coupler to a non-linear termination circuit, and reflecting a modified input signal from the non-linear termination circuit back through the reflective hybrid coupler as an output signal, the output signal having a third non-linear distortion profile shaped to compensate for the first non-linear distortion profile.