A compact demodulation reference is disclosed for compatibility with reduced-capability user devices, and for enhanced throughput for high-performance user devices of 5G and 6G in high-density environments. The demodulation reference, in some embodiments, occupies only one resource element, yet provides sufficient information to enable a receiver to calculate all of the amplitude or phase modulation levels of the modulation scheme. For example, if the modulation scheme is 16QAM, the demodulation reference can include an I branch with the highest amplitude level of the modulation scheme and an orthogonal Q branch with the lowest amplitude level. Further examples apply to a multiplexed amplitude-phase modulation scheme. In each case, the receiver can calculate the remaining amplitude (or phase) modulation levels, and thereby demodulate a proximate message. Further examples show how to reveal faulted message elements by comparing demodulation with QAM and amplitude-phase demodulation, and how to optimize noise margins.

A microelectromechanical system (MEMS) gyroscope sensor has a sensing mass and a quadrature error compensation control loop for applying a force to the sensing mass to cancel quadrature error. To detect fault, the quadrature error compensation control loop is opened and an additional force is applied to produce a physical displacement of the sensing mass. A quadrature error resulting from the physical displacement of the sensing mass in response to the applied additional force is sensed. The sensed quadrature error is compared to an expected value corresponding to the applied additional force and a fault alert is generated if the comparison is not satisfied.

An in-phase and quadrature mismatch compensator for a quadrature transmitter includes a delay element, a complex-valued filter and an adder. The delay element receives an input transmit signal and outputs a delayed transmit signal. The complex-valued filter receives the input transmit signal and outputs a selected part of a filtered output transmit signal. The adder adds the delayed transmit signal and the selected part of the filtered output transmit signal and outputs a pre-compensated transmit signal. In one embodiment, the selected part of the filtered output transmit signal includes the real part of the complex-valued output transmit signal. In another embodiment, the selected part of the filtered output transmit signal includes the imaginary part of the complex-valued output transmit signal. Two transmit real-valued compensators are also disclosed that combine the in-phase and quadrature signals before being filtered.

A microelectromechanical system (MEMS) gyroscope sensor has a sensing mass and a quadrature error compensation control loop for applying a force to the sensing mass to cancel quadrature error. To detect fault, the quadrature error compensation control loop is opened and an additional force is applied to produce a physical displacement of the sensing mass. A quadrature error resulting from the physical displacement of the sensing mass in response to the applied additional force is sensed. The sensed quadrature error is compared to an expected value corresponding to the applied additional force and a fault alert is generated if the comparison is not satisfied.

A Radio Frequency Impairments (RFI) compensator and a process to remove RFI is disclosed. The RFI compensator including: a conjugator to conjugate a signal {tilde over (x)}[n] to provide a signal {tilde over (x)}*[n]; and a filter to apply coefficients that equalize a linear distortion of the signal {tilde over (x)}[n] and reject an interfering image of the signal {tilde over (x)}*[n]. The signal {tilde over (x)}[n] maybe a single wideband carrier or may include multiple carriers at different carrier frequencies.

Receiver circuitries having multiple branches, such as unrolled feedback equalizers and fractional-rate receivers, may present differences between filtering elements of different branches with common filter inputs. Embodiments include devices capable of calibration that compensates such differences. The devices may be capable of introducing front-end offsets to emphasize the mismatches, and sweep filter input values to calculate the mismatches, and introducing offsets in the branches to compensate for the mismatches. Methods for use of the calibration devices are also described.

Quadrature clock generation circuits and techniques are disclosed. An example quadrature clock generator includes an in-phase (I) clock generation circuit to generate an I clock signal based on a reference clock signal, the I clock signal and the reference clock signal each having a first frequency, a quadrature phase (Q) clock generation circuit to generate a Q clock signal based on the reference clock signal, a rise time control signal, and a fall time control signal, the Q clock signal having the first frequency, and a control circuit to generate the rise time control signal and the fall time control signal based on the I clock signal and the Q clock signal.

To reduce signal distortion, a remote terminal receives a quadrature-modulated transmitter-check signal from a user terminal. The remote terminal measures an in-phase/quadrature (I/Q) imbalance error and/or a direct current (DC) offset error in the transmitter-check signal. The remote terminal then transmits to the user terminal transmitter-correction information derived from an I/Q imbalance error or a DC offset error. The transmitter-correction information is for counteracting the I/Q imbalance error or the DC offset error at the user terminal.

A signal compensation device comprises a first filter circuit, for processing a broadband signal, to generate a first analog time-domain signal; a second filter circuit, for processing the broadband signal, to generate a second analog time-domain signal; a first transform circuit, for transforming the first analog time-domain signal to a first digital time-domain signal; a second transform circuit, for transforming the second analog time-domain signal to a second digital time-domain signal; a third transform circuit, for transforming the first digital time-domain signal to a first frequency-domain signal; a fourth transform circuit, for transforming the second digital time-domain signal to a second frequency-domain signal; and a processing circuit, for generating a time-domain compensation response according to the first frequency-domain signal and the second frequency-domain signal.

A method of pre-compensating for transmitter in-phase (I) and quadrature (Q) mismatch (IQMM) may include sending a signal through an up-converter of a transmit path to provide an up-converted signal, determining the up-converted signal, determining one or more IQMM parameters for the transmit path based on the determined up-converted signal, and determining one or more pre-compensation parameters for the transmit path based on the one or more IQMM parameters for the transmit path. In some embodiments, the up-converted signal may be determined through a receive feedback path. In some embodiments, the up-converted signal may be determined through an envelope detector.