A power feed circuit for a circularly polarized antenna includes a synthesizing-distributing unit and a phase shift unit. The synthesizing-distributing unit distributes input signals to two paths with the same phase and same amplitude. The phase shift unit has two phase shift circuits connected respectively between the two paths distributed by the synthesizing-distributing unit and two feed points of a circularly polarized antenna. The phase shift unit outputs signals whose phase difference is 90° to the two feed points and of the circularly polarized antenna.

In accordance with an embodiment, a differential directional coupler includes a first coupler having a first transformer comprising a first input coil and a first output coil, and a second coupler having a second transformer comprising a second input coil and a second output coil. The first input coil and the second input coil each include an input port, the first transformer at least partially covers the second transformer in a top view from a vertical direction onto the differential directional coupler, and the first input coil and the second input coil are configured to be mirror symmetric with respect to one another in the top view with respect to their input ports.

Apparatus and methods for vector modulator phase shifters are provided. In certain embodiments, a phase shifter includes a quadrature filter that filters a differential input signal to generate a differential in-phase (I) voltage and a differential quadrature-phase (Q) voltage, an in-phase variable gain amplifier (I-VGA) that amplifies the differential I voltage to generate a differential I current, a quadrature-phase variable gain amplifier (Q-VGA) that amplifies the differential Q voltage to generate a differential Q current, and a current mode combiner that combines the differential I voltage and the differential Q voltage to generate a differential output signal. A phase difference between the differential output signal and the differential input signal is controlled by gain settings of the I-VGA and the Q-VGA.

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.

A radio-frequency chip is provided, and relates to the field of chip technologies, to reduce a component loss caused by redundant components in the radio-frequency chip. The radio-frequency chip includes a phased array, the phased array includes a plurality of branches, and each of the plurality of branches includes a transmitting path, a receiving path, a common path, and a phase shifter. The phase shifter includes a first phase shift unit, a second phase shift unit, and a third phase shift unit. The first phase shift unit is located on the transmitting path, the second phase shift unit is located on the receiving path, and the third phase shift unit is located on the common path.

A wideband tunable frequency single-subband converter is proposed. The wideband frequency tunable converter operates within a wideband and tunable frequency range, and has process, voltage, and temperature (PVT) tracking capability. In one embodiment, the wideband converter comprises a frequency tunable polyphase filter having a plurality of switchable polyphase resistors. The polyphase resistors are controlled by a frequency tuning control signal to achieve wideband frequency tunability. In a preferred embodiment, a triode mode transistor is used as a polyphase resistor, and a different resistance value of the polyphase filter is realized by turning on one or multiple of the different transistors in triode mode. In addition, a constant Gm(R) bias generator is used to provide the gate biases to the triode mode transistors to maintain a constant and stable resistance value across PVT and other variation.

A wideband tunable frequency single-subband converter is proposed. The wideband frequency tunable converter operates within a wideband and tunable frequency range, and has process, voltage, and temperature (PVT) tracking capability. In one embodiment, the wideband converter comprises a frequency tunable polyphase filter having a plurality of switchable polyphase resistors. The polyphase resistors are controlled by a frequency tuning control signal to achieve wideband frequency tunability. In a preferred embodiment, a triode mode transistor is used as a polyphase resistor, and a different resistance value of the polyphase filter is realized by turning on one or multiple of the different transistors in triode mode. In addition, a constant Gm(R) bias generator is used to provide the gate biases to the triode mode transistors to maintain a constant and stable resistance value across PVT and other variation.

In an embodiment, an off-grid phase splitter includes: a first input port and a second input port that are separately connected to a power supply; a first output port and a second output port that provide a second voltage, and the second output port and a third output port provide a third voltage; a first capacitor connected between the first output port and the second output port; a second capacitor connected between the second output port and the third output port; a first switch circuit and a second switch circuit connected in series to form a first node between the first input port and the second input port, where the first switch circuit and the second switch circuit are unidirectionally switched on in opposite directions,; and an inductor connected between the first node and the second output port.

In an embodiment, an off-grid phase splitter includes: a first input port and a second input port that are separately connected to a power supply; a first output port and a second output port that provide a second voltage, and the second output port and a third output port provide a third voltage; a first capacitor connected between the first output port and the second output port; a second capacitor connected between the second output port and the third output port; a first switch circuit and a second switch circuit connected in series to form a first node between the first input port and the second input port, where the first switch circuit and the second switch circuit are unidirectionally switched on in opposite directions,; and an inductor connected between the first node and the second output port.

The present invention provides a filtering circuit comprising a poly phase filter and a quadrature phase detector. The poly phase filter comprises a first path, a second path, a third path and a fourth path. The first path is configured to receive a first input signal to generate a first clock signal. The second path comprising a first adjustable delay circuit is configured to receive the first input signal to generate a second clock signal. The third path comprising a second adjustable delay circuit is configured to receive a second input signal to generate a third clock signal. The fourth path is configured to receive the second input signal to generate a fourth clock signal. The quadrature phase detector is configured to detect phases of these clock signals to generate control signals to control the first adjustable delay circuit and the second adjustable delay circuit.