An apparatus is disclosed for phase-shifting signals with a compensation circuit. In example implementations, an apparatus for phase-shifting signals includes a phase shifter having a first port and a second port. The phase shifter also includes a signal phase generator, a compensation circuit, and a vector modulator. The compensation circuit includes a first capacitor with a first capacitance and a second capacitor with a second capacitance. The first capacitance is different from the second capacitance. The signal phase generator is coupled between the first port and the compensation circuit. The vector modulator is coupled between the compensation circuit and the second port.

A radio frequency (RF) transmitter including a switched-capacitor digital-to-analog converter (SC-DAC) configured to selectively generate a first RF output signal having a first output power control range or a second RF output signal having a second output power control range from input signals received through a plurality of lines may be provided.

Technology for a combined duplexer is disclosed. The combined duplexer can include a first common port and a second common port, a first first direction filter is configured to pass a first direction signal in a first frequency band and, a first second direction filter to pass a second direction signal in a second frequency band, and a second first direction filter to pass the first signal in the first frequency band. The first first direction filter and the first second direction filter share the first common port. The first second direction filter and the second first direction filter share the second common port.

According to an aspect, there is provided a method for power-amplification of a transmission signal, comprising: obtaining the transmission signal with phase and amplitude modulation; generating a power-amplified polar signal for approximating a power-amplified transmission signal by power-amplifying a first constant-envelope signal with one of two or more first amplification factors based on the transmission signal; generating an outphasing pair of a first power-amplified outphasing signal and a second power-amplified outphasing signal based on the transmission signal; and combining the power-amplified polar signal, the first power-amplified outphasing signal and the second power-amplified outphasing signal to provide the power-amplified transmission signal.

A technology is described for a repeater architecture having a combined direct digital channelizer (DDC). The DDC can be coupled to a signal combiner and a breakout signal divider to enable bidirectional signals to be communicated to the DDC. A first direction receive amplification and filtering path can be coupled between a first antenna port and the signal combiner. A second direction receive amplification and filtering path can be coupled between a second antenna port and the signal combiner. A first direction transmit amplification and filtering path can be coupled between the breakout signal divider and the first antenna port. A second direction transmit amplification and filtering path can be coupled between the breakout signal divider and the second antenna port.

The present application provides a method for calibrating a transmitter. The transmitter includes an oscillator, a first signal path, and a second signal path. The first signal path and the second signal path include a first calibration unit preceding a first low pass filter and a second low pass filter, and a second calibration unit succeeding the first low pass filter and the second low pass filter. The calibration method inlcudes: by configuring the first calibration unit and the second calibration unit and sending a transmission signal, and performing frequency analysis upon the transmission signal to obtain a frequency analysis result, to generate an optimized first compensation value for the first calibration unit and an optimized second compensation value for the second calibration unit.

Described are concepts, systems and techniques for dividing a communication channel such that no single radio frequency (RF) power amplifier (PA) in a remote radio head (RRH) operates over an excessively wide frequency bandwidth. This allows efficient operation of the RF PA wherein each PA transmit path is tuned for operation at a respective one of a plurality of different center frequencies (f.sub.0, f.sub.0+Δf, . . . f.sub.0+(n−1)Δf where n is an integer corresponding to the number of RF PA transmit paths.

A radio frequency module includes a module substrate having a principal surface, one or more circuit components disposed on a principal surface side, a resin member disposed on the principal surface side and covering a side surface of the one or more circuit components, a metal shield layer in contact with a top surface of the resin member and a top surface of the one or more circuit components, and an engraved portion provided on the top surface of the one or more circuit components.

A communications apparatus includes a phase correction unit, a first radio frequency channel, a first analog bridge, a second radio frequency channel, and a second analog bridge. A first signal is sent to a first input end using the first radio frequency channel, and is divided into at least two channels of first sub-signals by using the first analog bridge. The at least two channels of first sub-signals are respective output from at least two first output ends to at least two first antenna arrays. Similarly, a second signal is divided into at least two channels of second sub-signals by using the second analog bridge, and the at least two channels of second sub-signals are output to at least two second antenna arrays. A first channel of first sub-signal and a first channel of second sub-signal are coupled to the phase correction unit by using a coupler.

Examples disclosed herein relate to a vector modulator architecture, having an input splitter network configured to receive a radio frequency (RF) input signal and generate a plurality of quadrature signals at different phases, a variable gain amplifier (VGA) stage coupled to the input splitter network and configured to apply a first gain to one or more of the plurality of quadrature signals, a power combiner coupled to the VGA stage and configured to combine the plurality of quadrature signals into a combined RF signal, and a power amplifier (PA) stage coupled to the power combiner and configured to apply a second gain to the combined RF signal and generate an output RF signal. Other examples disclosed herein relate to an antenna system for autonomous vehicles and a radar system for use in an autonomous driving vehicle.