Analog Devices,inc.

Analog Devices Global

Analog Devices Technology

Analog Devices International Unlimited Company

David J Mclaurin

Antonio J Montalvo

Steven R Bal

Raju Hormis

Christopher Mayer

Kevin Glenn Gard

Martin McCormick

Jianxun Fan

Patrick Joseph Pratt

Trevor Clifford Caldwell

David Nelson Alldred

Zhao Li

Victor Kozlov

Reza Alavi

Shipra Bhal

Christopher W Angell

Peadar Antony Forbes

Chris Angell

Tolga Pamir

Lu Wu

Sudhir Desai

Brian Reggiannini

Ahmed Ali

Hatice Ozis Unsal

Richard Schubert

Gordon Allen

Martin Mccormick

Embodiments of the present disclosure relate to cellular technology applications of beamforming performed in the digital domain. In one aspect, an RF system for performing digital beamforming on a per-carrier basis is disclosed, where different phase and/or amplitude adjustments are applied to signals of different frequency ranges (i.e., to different carrier signals). In another aspect, an RF system for performing digital beamforming on a per-antenna basis is disclosed, where different phase and/or amplitude adjustments are applied to signals transmitted from or received by different antennas. In some embodiments, an RF system may be configured to implement both digital beamforming on a per-carrier basis and digital beamforming on a per-antenna basis. The RF systems disclosed herein allow implementing programmable beamforming in the digital domain in a manner that is significantly less complex than conventional implementations.

Digital beamforming for cellular technology applications

A transmission module is provided that includes a transmitter, a loopback receiver, and a QEC controller. The QEC controller identifies quadrature imbalance in the transmitter based at least one a comparison of the data signals at the output of the loopback receiver with data signals at the input of the transmitter. Based on the comparison, the QEC controller can adjust one or more characteristics of the transmitter to correct quadrature errors in the transmitter.

Wideband quadrature error detection and correction

Transmitter noise cancellation may be applied on a channel by channel basis to active channels of an incoming radio frequency signal received at a receiver. A noise cancellation filter may be provided for each active channel in a predetermined signal band. Applying noise cancellation on a per active channel basis instead of to the entire receive band may substantially reduce the filtering requirement and number of filter coefficients or taps to save power and reduce manufacturing costs. Channelized transmitter noise cancellers, multi transmitter-receiver cross coupling cancellers, and hybrid full signal band and channelized transmitter noise cancellers are also provided.

Radio frequency transmitter noise cancellation

A method and apparatus for estimating and compensating TX LO leakage using circuitry on a loopback path connecting the transmitter and receiver are provided. The TX LO leakage may be estimated by measuring the DC signal on the receiver, measuring the phase difference between the received LO signal and the receiver LO signal, and filtering LO harmonics that may arise from the use of non-linear mixers. The DC signal on the receiver may be measured by opening and closing the loopback path, or changing the gain of the loopback path, or flipping the phase of looped back TX signal. The method may be used in an initialization or tracking calibration scheme.

Transmitter LO leakage calibration scheme using loopback circuitry

A transmission module is provided that includes a transmitter, a loopback receiver, and a QEC controller. In a first state, the QEC controller calibrates the loopback receiver to remove quadrature imbalance in the loopback receiver. In a second state, a communication pathway is provided between the transmitter and the loopback receiver, and the QEC controller identifies quadrature imbalance in the transmitter based at least one a comparison of the data signals at the output of the loopback receiver with data signals at the input of the transmitter. Based on the comparison, the QEC controller can adjust one or more characteristics of the transmitter to correct quadrature errors in the transmitter.

Wideband quadrature error correction

A system and method provide for calibrating the frequency response of an electronic filter. The system and method include a radio transmitter with both in-phase and quadrature baseband paths. Each baseband path includes a numerically controlled oscillator ('NCO'), a digital signal path, a digital-to-analog converter ('DAC'), and an analog filter. A low frequency tone is applied from the NCO from one of the baseband path, while a high frequency tone is applied from the NCO in the other baseband path. An analog peak detector at output determines which analog filter has the largest amplitude at the output. The peak detector offset between the two analog filters is offset by stimulating the in-phase and quadrature baseband paths with the respective NCOs to find an amplitude difference between the output signals from the NCOs that makes the output of the analog filters the same. Calibration is then performed on the corner frequency and filter peaking through respective stimulation of the in-phase and quadrature baseband paths. The system and method is advantageous as it allows for very accurate calibration of both the filter corner frequency and peaking during a standard transmission operating mode with little additional hardware required.

System and method to calibrate the frequency response of an electronic filter

A calibration system for an analog-to-digital converter (ADC) an internal ADC that receives an analog input and converts the analog input to digital multi-bit data. The calibration system also includes a reference shuffling circuit that shuffles reference values of comparators of the internal ADC. Further, the calibration system includes a calibration circuit that calibrates the comparators of the internal ADC. The calibration system includes a digital block that measures an amplitude based on the digital multi-bit data. Additionally, the calibration system includes calibration logic that controls the calibration circuit based on an output of the digital block.

System, method and recording medium for analog to digital converter calibration

A system and method provide for a radio transmitter with digital predistortion. The radio transmitter includes a high output power narrowband upconverter and a low output power wideband upconverter. In a stage of the radio transmitter, digital predistortion is applied to transmit data by setting digital coefficients by a digital predistortion algorithm, resulting in a predistortion signal. A predistortion signal is separated into a narrowband component and a wideband component, where the narrowband component corresponds to a desired traffic signal and the wideband component corresponds to a digital predistortion signal reflecting separated digital predistortion correction products. The narrowband upconverter provides a transmission path for a desired traffic signal or transmit data (the narrowband component of the digital predistortion signal), while the wideband upconverter provides a transmission path for the wideband component representing digital predistortion correction products.

System and method to implement a radio transmitter with digital predistortion having reduced noise

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Durham, NC, United States of America

David J Mclaurin