A circuit includes a polar transmitter to generate a radio frequency output from amplitude and phase signal components. The polar transmitter includes an amplifier to combine amplitude and phase signal components. A processor is coupled to the polar transmitter to provide the amplitude and phase signal components. The processor includes: a digital modulation circuit to generate a modulated digital signal including in-phase and quadrature signal components and a correction circuit to calculate and apply a complex digital offset for local oscillator feedthrough of the amplifier. The complex digital offset includes an in-phase offset correction factor and a quadrature offset correction factor.

An apparatus comprising a local oscillator (LO) for driving a mixer, the LO being configured to oscillate at an oscillation frequency, and generate a first set of LO signals, wherein each of the first set of LO signals has a LO signal frequency equal to a first multiplication factor m multiplied by the oscillation frequency, the first multiplication factor m, being an integer greater than or equal to two, and each of the first set of LO signals is separated by adjacent LO signals by a phase difference equal to 360° divided by a first variable n, the first variable n being an integer that is greater than or equal to two.

A travelling wave mixer (TWM) is provided that includes an input artificial transmission line configured to transmit an input signal, an output artificial transmission line configured to transmit an output signal, a local oscillator (LO) artificial transmission line configured to transmit an LO signal, and a plurality of mixer stages connected in parallel between the output artificial transmission and the input artificial transmission line. Each of the mixer stages includes an input amplifier, a mixer and an output amplifier connected in series between the input artificial transmission line and the output artificial transmission line, where an input of the mixer receives an output of the input amplifier, and an output of the mixer is applied to an input of the output amplifier. Further, each of the mixer stages includes a phase-adjustable LO amplifier circuit connected between the LO artificial transmission line and an LO input of the mixer, where the phase-adjustable LO amplifier is configured to adjust an LO signal phase applied to the LO input of each mixer to null out a phase error in each mixer stage independently.

A mixer for generating an analog output signal X.sub.OUT from an analog input signal X.sub.IN using a mixing signal having a mixing frequency f.sub.MIX, the mixer comprising: a scaler being configured to sample the analog input signal X.sub.IN at a plurality of discrete points in time k with a sampling frequency f.sub.S to obtain a sampled analog input signal X.sub.IN[k] having a continuous signal value, and to generate the analog output signal X.sub.OUT having a continuous signal value by scaling the sampled analog input signal X.sub.IN[k] on the basis of a plurality of scaling coefficients A[k], wherein the scaling coefficients A[k] are a time-discrete representation of the mixing signal.

A semiconductor device comprising at least one transmit path is provided. The transmit path comprises an input node for receiving a digital baseband signal. Further, the transmit path comprises digital mixer circuitry coupled to the input node and configured to generate an upconverted digital baseband signal by upconverting a frequency of the digital baseband signal. Additionally, the transmit path comprises Digital-to-Analog Converter (DAC) circuitry coupled to the digital mixer circuitry and configured to generate an analog radio frequency signal based on the upconverted digital baseband signal. The transmit path comprises first analog mixer circuitry coupleable to an output of the DAC circuitry, and second analog mixer circuitry coupleable to the output of the DAC circuitry. Further, the transmit path comprises a first output node coupleable to an output of the first analog mixer circuitry, and a second output node coupleable to an output of the second analog mixer circuitry.

The present disclosure generally relates to the field of receiver structures in radio communication systems and more specifically to passive mixers in the receiver structure and to a technique for converting a first signal having a first frequency into a second signal having a second frequency by using a third signal having a third frequency. A passive mixer for converting a first signal having a first frequency into a second signal having a second frequency by using a third signal having a third frequency comprises a cancellation component 220 for generating a first cancellation signal for cancelling second order intermodulation components by superimposing the first signal weighted by a cancellation value on the third signal; and a mixing component 231 having a first terminal 232 for receiving the first signal, a second terminal 234 for outputting the second signal, and a third terminal 236 for receiving the first cancellation signal, wherein the mixing component 231 is adapted to provide the second signal as output at the second terminal 234 by mixing the first signal provided as input at the first terminal 232 and the first cancellation signal provided as input at the third terminal 236.

A system and method for determining an Angle of Arrival (AOA) for frequency modulated communications. The system may include first and second antennas spaced apart from each other by a distance, and configured to receive wireless communications in the form of a modulated signal. The system may determine a phase difference between the received signals based on one or more samples of a dedicated portion of the received signals, where one or more aspects of the dedicated portion is variable.

An apparatus is disclosed for flexible beamforming using frequency-division multiplexing. In an example aspect, an apparatus includes an antenna array and a wireless transceiver with two or more dedicated receive paths respectively coupled to two or more antenna elements of the antenna array, two or more mixers, a first combiner, a second combiner, and a switching circuit. The first combiner has a first input coupled to a first dedicated receive path and an output coupled to an input of a first mixer. The second combiner has a first input coupled to an output of the first mixer and a second input coupled to an output of a second mixer. The switching circuit is configured to selectively connect a second dedicated receive path to a second input of the first combiner or connect the second dedicated receive path to an input of the second mixer.

A harmonic-rejection mixer apparatus includes a mixing circuit and a combining circuit. The mixing circuit receives mixes an input signal and a first local oscillator (LO) signal to generate a first output signal, and mixes the same input signal and a second LO signal to generate a second output signal, wherein the first LO signal and the second LO signal have a same frequency but different phases. The combining circuit combines the first output signal and the second output signal, wherein harmonic rejection is at least achieved by combination of the first output signal and the second output signal.

An apparatus, a system, and a chip are provided for improving RF system performance in MRI systems. The apparatus includes a radio-frequency (RF) coil array disposed at least partially in a coil housing, where the RF coil array may include at least one coil configured to receive magnetic resonance (MR) RF signals. The apparatus also includes a mixer disposed in the coil housing and electronically connected to the RF coil array, where the mixer converts MR RF signals from the RF coil array to intermediate-frequency (IF) signals. An electronic amplifier is disposed in the coil housing. The electronic amplifier is electronically connected to the mixer and is configured to amplify IF signals from the mixer to amplified IF signals.