Apparatus and methods for quadrature combined Doherty amplifiers are provided herein. In certain embodiments, a separator is used to separate a radio frequency (RF) input signal into a plurality of input signal components that are amplified by a pair of Doherty amplifiers operating in quadrature. Additionally, a combiner is used to combine a plurality of output signal components generated by the pair of Doherty amplifiers, thereby generating an RF output signal exhibiting quadrature balancing.

An aspect relates to a signal power splitter/combiner including a first signal port; a first resistor; a first impedance transformer coupled in series with the first resistor between the first signal port and a first intermediate node; a second impedance transformer coupled between the first intermediate node and a second signal port; a third impedance transformer coupled between the first intermediate node and a third signal port; and a second resistor coupled between the second and third signal ports. The signal power splitter/combiner may further include a fourth impedance transformer coupled between the second impedance transformer and the second signal port, a fifth impedance transformer coupled between the third impedance transformer and the third signal port; and a third resistor coupled between a third intermediate nod.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

Embodiments of resonator circuits and modulating resonators and are described generally herein. One or more acoustic wave resonators may be coupled in series or parallel to generate tunable filters. One or more acoustic wave resonances may be modulated by one or more capacitors or tunable capacitors. One or more acoustic wave modules may also be switchable in a filter. Other embodiments may be described and claimed.

The present invention is a signal isolation device comprising: a first circulator; a second circulator connected to the first circulator; a first radio frequency switch connected to the second circulator; an adjustable radio frequency limiter connected to the first radio frequency switch; a low noise amplifier connected to the adjustable radio frequency limiter; a bandpass filter connected the low noise amplifier; a power splitter connected the bandpass filter; an attenuator connected to the power splitter; a second radio frequency switch connected to the power splitter; an active filter chain connected to the second radio frequency switch; a third circulator connected to the attenuator and the first circulator; a power detector connected to the third circulator; and a trigger generator connected to the power detector.

A radio-frequency (RF) splitter is provided. The RF splitter includes a common branch node configured to transfer an RF signal, input from an input port, to at least one of first and second output ports, first and second branch nodes electrically connected between the common branch node and the first and second output ports, first and second series switches configured to control switching operations to electrically connect the common branch node and the first and second branch nodes to each other, first and second inductors electrically connected between the common branch node and the first and second branch nodes, a resistor electrically connected between the first and second branch nodes, and first and second shunt switches configured to control switching operations to electrically connect the first and second branch nodes and the resistor to each other.

A radio-frequency (RF) splitter is provided. The RF splitter includes a common branch node configured to transfer an RF signal, input from an input port, to at least one of first and second output ports, first and second branch nodes electrically connected between the common branch node and the first and second output ports, first and second series switches configured to control switching operations to electrically connect the common branch node and the first and second branch nodes to each other, first and second inductors electrically connected between the common branch node and the first and second branch nodes, a resistor electrically connected between the first and second branch nodes, and first and second shunt switches configured to control switching operations to electrically connect the first and second branch nodes and the resistor to each other.

A phase shifter circuit and a power divider are disclosed. The phase shifter circuit provides a (90/N)-degree phase shift for a signal with two or more frequencies, where N is an integer. The phase shifter circuit includes a first inductor, a first capacitor, a second inductor and a second capacitor. The first inductor is grounded, and is coupled to the first capacitor in series. The second inductor is grounded, and is coupled to the second capacitor in series. A first node between the first capacitor and the first inductor is coupled to a node between a second node between the second capacitor and the second inductor. The power divider includes plural circuit blocks cascaded in series. Each circuit block provides a (90/N)-degree phase shift for a signal with two or more operating frequencies.

Embodiments of a method and an apparatus for a quadrature hybrid are disclosed. In an embodiment, a quadrature hybrid includes a first port, a second port, a third port, a fourth port, first, second, and third inductors, first, second, third, and fourth capacitors, and a first variable capacitor tuning network connected between the first port and the fourth port, and a second variable capacitor tuning network connected between the second port and the third port.

Radio-frequency splitter circuits, devices and methods. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.