Texas Instruments Corporation

Quartics, Inc.

Other

Samsung Electronics Co., Ltd.

Texas Instrumentals Incorporated

Imtinan Elahi

Khurram Muhammad

Sherjil Ahmed

Chih-Ming Hung

Michael Brobston

Lup Meng Loh

Naveen Krishna Yanduru

Mohammad Usman

Hunsoo Choo

Yongtao Wang

Jon Laurent Pang

Amjad Luna

An RF transmitter comprises a digital-to-IF circuit block configured to receive a digital in-phase baseband signal and a digital quadrature baseband signal and to up-convert the digital in-phase and quadrature baseband signals to a digital in-phase IF signal and to a digital quadrature IF signal. The wireless RF transmitter further comprises an IF-to-RF circuit block configured to convert the digital in-phase and quadrature IF signals to analog signals and to up-convert the analog in-phase and quadrature IF signals to an RF output signal. The digital-to-IF circuit block comprises pre-compensation circuitry configured to reduce analog impairments associated with the IF-to-RF circuit block.

Quadrature digital-IF transmitter without inter-stage SAW filter and devices using same

A full duplex transceiver has cancellation circuitry that includes an auxiliary receiver and an auxiliary transmitter. More specifically, an analog received signal that includes transmission signal leakage is provided to a low noise amplifier (LNA), which then provides its output to a main receiver and the auxiliary receiver. The auxiliary receiver includes a portion operable to convert the received signal from the analog domain to the digital domain. The auxiliary receiver additionally includes a cancellation processor that determines the transmission signal leakage and generates a signal based on the determined leakage. This signal generated by the auxiliary receiver is provided to the auxiliary transmitter, which converts the digital signal back to the analog domain and generates a cancellation signal. The analog cancellation signal is fed back and added to the received signal at the input of the LNA. As a result of the feedback system including an auxiliary receiver and an auxiliary transmitter, transmission signal leakage of many types may be canceled from a received signal.

System and method for transmission interference cancellation in full duplex transceiver

Methods and apparatus for canceling distortion in full-duplex transceivers are disclosed. Some example methods to reduce distortion in a full-duplex transceiver include generating a first digital signal, generating a first analog signal based on the first digital signal for transmission over a full-duplex channel, receiving a second analog signal via the full-duplex channel, and generating a second digital signal based on the second analog signal, wherein the second digital signal includes coupling distortion based on the first analog signal. The example methods further include generating an adaptive filter signal based on the first digital signal, and reducing the coupling distortion from the second digital signal by subtracting the adaptive filter signal from the second digital signal.

Methods and apparatus for canceling distortion in full-duplex transceivers

Methods, apparatus, and articles of manufacture are described for improving distortion performance and for direct current offset cancellation in receivers. In one example, a method of improving distortion in a receiver includes determining a direct current (DC) amplitude of an offset signal, generating the offset signal, and providing the offset signal to an output of a mixer to improve the distortion performance of the mixer.

Methods and apparatus to improve distortion performance and direct current (DC) offset cancellation in receivers

A method of increasing linearity of an RF signal receive path includes measuring a signal amplified by the receive path. The receive path has a local oscillator operating at an LO frequency and a ground. An error signal is determined from the amplified signal, the error signal being representative of the nonlinearity. An anti-spur tone is injected into the ground. The anti-spur tone has a frequency about equal to the LO frequency and an amplitude and phase that are determined to increase the linearity of the receive path.

Linearity of an RF receive path by spurious tone suppression

A cost-efficient digital CATV network to improve signal quality, provide reliability, and offer the ability to meet demands for interactive services is described. Analog or digital video downstream channels are converted to a digital format by a digital headend transmitter. Relatively costly error-encoding for digital video channels is also part of the digital headend transmitter. Downstream analog and digital video channels in the digital format are transmitted using time-division multiplex technology from a headend to nodes using standard network protocols, such as SONET. Standard network protocols provide error-monitoring and status indication of transmit data, thus ensuring high signal quality and reliability. Time-division multiplexing facilitates easy adding or dropping of information to a transmit path. Flexibility to add or drop information is critical in providing interactive services. Data from interactive services can be added or dropped at points of presence throughout the digital CATV network. Subscribers to the digital CATV network can communicate with each other. A digital node transmitter receives the analog or digital video channels in digital format and converts the analog or digital video channels into an analog format. The digital node transmitter also frequency-division multiplexes multiple analog or digital video channels into one analog broadband signal for broadcast to subscribers' homes.

Method and apparatus for a digitized CATV network for bundled services

The present invention provides a local oscillator (LO) leakage controller for use with a receiver. In one embodiment, the LO leakage controller includes a comparison unit configured to process an LO leakage error signal from the receiver to provide a leakage cancellation signal. Additionally, the LO leakage controller also includes a leakage counterbalance unit coupled to the comparison unit and configured to adapt the leakage cancellation signal to the receiver to counterbalance LO leakage in the receiver.

Local oscillator leakage counterbalancing in a receiver

The present invention pertains to a method of calibrating reception properties of a radio frequency (RF) processor. The application describes two embodiments of the invention representing calibration of the properties using an auxiliary transmitter to generate a calibration signal internal to the RF processor.

RF processor having internal calibration mode

Methods and apparatus to compensate for I/Q mismatch in quadrature receivers are disclosed. An example apparatus disclosed herein comprises a correction engine using first filter coefficients to compensate for I/Q mismatch present in a received quadrature signal; an adaptation engine to adapt second filter coefficients based on I/Q mismatch present in the received quadrature signal; and coefficient controller to occasionally adjust the first filter coefficients based on the second filter coefficients.

Quadrature receiver with correction engine, coefficient controller and adaptation engine

One embodiment of the invention includes a mixed-signal filter. The mixed-signal filter comprises an analog signal path configured to process a first analog signal and an analog-to-digital converter (ADC) configured to convert the processed first analog signal to a digital signal. The mixed-signal filter also comprises a programmable digital feedback filter configured to filter the digital signal and a digital-to-analog converter (DAC) configured to convert the filtered digital signal to a second analog signal. The mixed-signal filter further comprises a signal combiner configured to combine an analog input signal of the mixed-signal filter and the second analog signal to generate the first analog signal.

Mixed-signal filter

Methods, apparatus, and articles of manufacture are disclosed for removing an undesired component from a low intermediate frequency signal having an intermediate center frequency and an undesired component at a first frequency. One example method may include determining an amplitude of the undesired component; frequency shifting the low intermediate frequency signal from the intermediate center frequency to produce a zero intermediate frequency signal; filtering the zero intermediate frequency signal; generating a tone based on the amplitude of the undesired component; and subtracting the tone from the filtered zero intermediate frequency signal to remove the undesired component.

Methods and apparatus to perform signal removal in a low intermediate frequency receiver

The present invention provides for adaptive filters that have improved computational and memory bandwidth proprieties. When applied to telecommunication applications, the present invention additionally provides for improved methods and systems of canceling echoes. In one embodiment of the adaptive filter of the present invention, a filter, preferably an adaptive finite impulse response (FIR) filter, of an appropriate length, N, is chosen. Once the filter is chosen, convergence is achieved and the filter is converted to an infinite impulse response (IIR) filter. In the course of operation, data is received from an input source and used to adapt the zeroes of the IIR filter using the least means square (LMS) approach, keeping the poles fixed. The adaptation process generates a set of converged filter coefficients that are then applied to the input signal to create a modified signal used to filter the data. The novel adaptive filter method and system presented herein can be used to improve the calculation of the echo impulse response by, among other things, reducing the computational complexity and memory requirements of the coefficient calculation conducted within the adaptive filter.

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Richardson, TX, United States of America

Imtinan Elahi