A baseband system includes: an estimation and compensation circuit estimating frequency-independent non-ideal effects based on an original IQ signal pair, and compensating the original IQ signal pair based on a result of the estimation to obtain a compensated IQ signal pair; a channel estimation and equalization circuit performing channel estimation and equalization based on the compensated IQ signal pair to obtain an equalized IQ signal pair; and a tracking and compensation circuit obtaining a result of tracking of residual quantities of the aforesaid non-ideal effects based on the equalized IQ signal pair, and compensating the equalized IQ signal pair based on the result of the tracking to obtain an output IQ signal pair.

An apparatus and method are provided for a communication scheme for converging a 5G communication system for supporting a higher data transfer rate than a post-4G system with the IoT technology. A method includes configuring a loopback path between a transmitter and a receiver; transmitting a preconfigured signal from the transmitter to the receiver through the loopback path; identifying an image signal, wherein the image signal includes a distorted signal of the preconfigured signal; determining a gain error value and a phase error value based on the preconfigured signal and the image signal; and performing I/Q calibration based on the gain error value and the phase error value. A subcarrier in which the preconfigured signal is transmitted and a subcarrier in which the image signal is generated do not overlap.

An apparatus includes a radio-frequency (RF) receiver. The RF receiver includes an analog-to-digital converter (ADC) to convert an analog input signal to a digital output signal in response to an ADC clock signal. The RF receiver further includes a frequency generator to selectively provide either a clock signal to be provided as the ADC clock signal or a signal to be used for in-phase-quadrature (IQ) calibration of the RF receiver.

Techniques are presented to improve the accuracy of and reduce the time required for calibration of an in-phase/quadrature (I/Q) transmission circuit. A measurement receiver measures the I/Q mismatch, where an RF phase shift is introduced to distinguish between the transmitter and measurement receiver I/Q mismatches. Rather than assuming an amount of introduced phase shift, a measurement is used to estimate the phase shift. This phase estimate is then used to determine and correct the I/Q mismatch in the transmitter and measurement receiver. An iterative process can be used to improve the I/Q correction factors. Using simple signal processing to measure the phase shift during calibration and to perform the image calibration calculations, the phase shifter requirements can be significantly relaxed, resulting in faster design time and reduced design area/cost. This approach results in reduced calibration time, thus contributing to reduced factory production time and enabling faster live mode image calibration.

Methods, circuits, and apparatus for calibrating an in-phase and quadrature (IQ) imbalance of a communication signal including an in-phase component and a quadrature component in a communication apparatus, the method including determining whether to calibrate the IQ imbalance of the communication signal in the communication apparatus; selecting, in response to a determination to calibrate the IQ imbalance of the communication signal, at least one of an amplitude calibration or a phase calibration; controlling, in accordance with the selected amplitude calibration or phase calibration, at least one of an in-phase delay circuit or a quadrature delay circuit to adjust a pulse of at least one of a first LO signal or a second LO signal to thereby generate at least one pulse-adjusted LO signal; and multiplying the at least one pulse-adjusted LO signal with the communication signal to thereby calibrate the IQ imbalance.

A system having a set of common hardware and common signal processing together with a common waveform family that can be used to achieve both efficient radar and efficient communications functions. The system includes a common radar/communications transmitter having a transmission antenna and a combined radar and communications receiver having a common reception antenna. The common radar/communications transmitter is configured to transmit combined radar/communications waveform-modulated signals comprising symbols, each symbol consisting of an up chirp and a down chirp. The combined radar and communications receiver includes a baseband radar signal processing module configured to estimate range and range rate of a radar object from the received symbols and a baseband communications signal processing module configured to detect slopes and initial phases of the up and down chirps of each received symbol.

A test instrument may include a transmitter configured to transmit signals to a unit under test, a receiver configured to receive signals from the unit under test, and a controller configured to generate a transmitter compensation filter by (i) transmitting, with the transmitter, complex multi-sine signals over a first plurality of observed frequencies within a predetermined baseband frequency range, (ii) estimating a first plurality of frequency responses that compensate for in-phase and quadrature (IQ) imbalance at the first plurality of observed frequencies within the predetermined baseband frequency range, and (iii) determining, using the first plurality of frequency responses, a transmitter polynomial surface, and to compensate, using the transmitter compensation filter, at least one of the signals to be transmitted by the transmitter to reduce IQ imbalance in the transmitted signals, including using the transmitter polynomial surface to calculate a frequency response that reduces the IQ imbalance in the transmitted signals.

A receiver circuit includes a quadrature signal generator to generate an in-phase (I) signal and a quadrature (Q) signal from a local oscillator signal and an IQ phase sense and control circuit to generate a phase adjustment code responsive to a phase error between quadrature signals generated by a plurality of mixers. The receiver circuit also includes a phase corrector to adjust a phase difference between the I and Q signals from the quadrature signal generator to generate corrected I and Q signals to be provided to the plurality of mixers.

An IQ estimation module comprising a powerup state IQ estimator configured to generate powerup state IQ estimates based on a powerup calibration of the IQ estimation module, a steady state IQ estimator configured to generate steady state IQ estimates during a steady state operation of the IQ estimation module, and an IQ estimate extender configured to determine differences between the powerup state IQ estimates and steady state IQ estimates at their respective frequency bins and adjust the powerup state IQ estimates to improve the accuracy of IQ estimates.

An input signal has a desired signal component and an interfering signal component superimposed thereon. Interfering component estimation processing is applied to the input signal, obtaining as a result a filtered signal comprising a sequence of filtered data samples. The filtered signal is subtracted from the input signal obtaining as a result an output signal comprising a sequence of output data samples. The interfering component estimation processing applies conjugating processing to the input signal, providing a conjugated version of the input signal. An adaptive signal processing coefficient is computed and adaptive signal processing is applied to the conjugated version of the input signal using the adaptive processing coefficient.