Octagonal phase rotator includes an I-mixer having an I-DAC for steering current between positive and negative phases of an in-phase signal depending on k I-DAC control bits of a control code, a Q-mixer having a Q-DAC for steering current between the positive/negative phases of a quadrature signal depending on k Q-DAC control bits of the code, and an IQ-mixer having n IQ-mixer units each comprising an IQ-DAC for switching a second current unit between the in-phase and quadrature signals, in dependence on a respective bit of n IQ-DAC control bits, and between the positive/negative phases of the in-phase and quadrature signals via I and Q polarity switches respectively of that component. I and Q polarity switches of some different IQ-DAC components switch depending on different I-DAC control bits and Q-DAC control bits respectively. A summation circuit sums weighted output signals from the mixers to produce an output signal of phase.

Embodiments of the present disclosure disclose a radio remote unit, a receiver, and a base station. The radio remote unit includes at least one receive channel pair, a first local oscillator module, a second local oscillator module, a local oscillator switching switch, and a controller. Each receive channel pair includes a first receive channel and a second receive channel. Each receive channel in each receive channel pair includes a filtering module, a frequency mixing module connected to the filtering module, and a digital processing module connected to the frequency mixing module. A frequency mixing module on the second receive channel is connected to the first local oscillator module and the second local oscillator module by the local oscillator switching switch. The controller is configured to receive an operating mode that is sent by a base station, and control the local oscillator switching switch to perform switching.

Octagonal phase rotator includes an I-mixer having an I-DAC for steering current between positive and negative phases of an in-phase signal depending on k I-DAC control bits of a control code, a Q-mixer having a Q-DAC for steering current between the positive/negative phases of a quadrature signal depending on k Q-DAC control bits of the code, and an IQ-mixer having n IQ-mixer units each comprising an IQ-DAC for switching a second current unit between the in-phase and quadrature signals, in dependence on a respective bit of n IQ-DAC control bits, and between the positive/negative phases of the in-phase and quadrature signals via I and Q polarity switches respectively of that component. I and Q polarity switches of some different IQ-DAC components switch depending on different I-DAC control bits and Q-DAC control bits respectively. A summation circuit sums weighted output signals from the mixers to produce an output signal of phase.

A compensation circuit of a power amplifier includes a varactor, a voltage sensor and a control circuit. The varactor is coupled to an input terminal of the power amplifier. The voltage sensor is arranged for detecting an amplitude of an input signal of the power amplifier to generate a detecting result. The control circuit is coupled to the varactor and the voltage sensor, and is arranged for controlling a bias voltage of the varactor to adjust a capacitance of the varactor according to the detecting result.

A compensation circuit of a power amplifier includes a varactor, a voltage sensor and a control circuit. The varactor is coupled to an input terminal of the power amplifier. The voltage sensor is arranged for detecting an amplitude of an input signal of the power amplifier to generate a detecting result. The control circuit is coupled to the varactor and the voltage sensor, and is arranged for controlling a bias voltage of the varactor to adjust a capacitance of the varactor according to the detecting result.

An improved quadrature modulator/demodulator (IQMD) may use two-phase quadrature local oscillator (LO) signal generation for generating 0 and 90 LO signals, and an anti-phase combiner/divider (at 0 and 180) on the RF (radio frequency) port. The IQMD may include mixers (which may be double-balanced passive mixers) that function as downconverters when a signal is incident at their radio frequency (RF) ports, and function as upconverters when signals are incident on their intermediate frequency (IF) ports. Accordingly, the IQMD may function as an I/Q modulator by connecting digital-to-analog converters (DAC) to the differential I and Q ports, and/or it may also function as an I/Q demodulator by connecting analog-to-digital converters (ADC) to the differential I and Q ports.

Apparatus comprises a memory configured to store a matrix of transmit data; a multi-element antenna; and a transmitter configured to transmit a signal from a multi-element antenna as part of a packet within a transmit period in a switching interval by: switching between different elements of the multi-element antenna in a sequence of transmit intervals within the transmit period; and deriving the signal for transmission in different transmit intervals from different ones of the transmit data in the matrix. Also, apparatus comprises a receiver configured to receive plural packets; and an accumulator configured, for each packet, to accumulate signals received in a switching interval of the packet. The apparatus is configured to: derive a correlation metric for each of the packets from the accumulated signals for the packets; identify a packet with the best correlation metric; identify a direction associated with the packet identified as having the best correlation metric; and provide the direction as an output.

An improved quadrature modulator/demodulator (IQMD) may use two-phase quadrature local oscillator (LO) signal generation for generating 0 and 90 LO signals, and an anti-phase combiner/divider (at 0 and 180) on the RF (radio frequency) port. The IQMD may include mixers (which may be double-balanced passive mixers) that function as downconverters when a signal is incident at their radio frequency (RF) ports, and function as upconverters when signals are incident on their intermediate frequency (IF) ports. Accordingly, the IQMD may function as an I/Q modulator by connecting digital-to-analog converters (DAC) to the differential I and Q ports, and/or it may also function as an I/Q demodulator by connecting analog-to-digital converters (ADC) to the differential I and Q ports.

An improved quadrature modulator/demodulator (IQMD) may use two-phase quadrature local oscillator (LO) signal generation for generating 0 and 90 LO signals, and an anti-phase combiner/divider (at 0 and 180) on the RF (radio frequency) port. The IQMD may include mixers (which may be double-balanced passive mixers) that function as downconverters when a signal is incident at their radio frequency (RF) ports, and function as upconverters when signals are incident on their intermediate frequency (IF) ports. Accordingly, the IQMD may function as an I/Q modulator by connecting digital-to-analog converters (DAC) to the differential I and Q ports, and/or it may also function as an I/Q demodulator by connecting analog-to-digital converters (ADC) to the differential I and Q ports.

An I/Q signal generating apparatus and phase shift apparatus using the same are provided, the I/Q signal generating apparatus including: a first resonance circuit whose one end is connected to a first input terminal and whose other end is connected to a first output terminal; and a second resonance circuit whose one end is connected to the other end of the first resonance circuit or a second input terminal, and whose other end is connected to a second output terminal, wherein the first resonance circuit and the second resonance circuit each include a resistor, a capacitor connected in parallel with the resistor, and an inductor connected in a form of a cross between the resistor and the capacitor.