Texas Instruments Corporation

Zigang Yang

Hardik Prakash Gandhi

Lars Jorgensen

Lei Ding

Fernando Alberto Mujica

Xiaohan Chen

Hongzhi Zhao

Raul Blazquez

Jie Yang

Roland Sperlich

Anand Ganesh Dabak

Srinath Hosur

Xiaolin Lu

Badri N Varadarajan

Murtaza Ali

Rahmi Hezar

William Louis Abbott

Charles Kasimer Sestok, Iv

Udayan Dasgupta

Michael Eugene Locke

Susan Yim

Gregory Copeland

Milind Anil Borkar

Channamallesh G Hiremath

Channamallesh Hiremath

Prasad Chivakula

Rao P Venkatasadasiva

Umashanker S Iyer

For crest factor reduction in a first signal having first and second components, the first component is delayed. A second signal is generated in response to detecting that a peak in the first component exceeds a predetermined threshold. Amplitude of the peak in the first component is reduced in response to detecting that the peak in the first component exceeds the predetermined threshold. Reducing amplitude of the peak in the first component includes adding the second signal to the delayed first component.

Circuits and methods for reducing the amplitude of complex signals

A system and method for reducing peak to average power ratio in a wireless communication system. A wireless communication system includes a radio frequency wireless transmitter that includes signal peak reduction circuitry configured to reduce peak to average power ratio of a signal to be transmitted by reducing amplitude of the signal to be transmitted that is greater than a predetermined amplitude. The signal peak reduction circuitry includes a bit inverter configured to invert a bit of a symbol identified as causing the amplitude of the signal to exceed the predetermined amplitude. The bit inverter is also configured to select the bit to invert such that inversion of the bit reduces the amplitude of the signal, and such that forward error correction in a receiver wirelessly coupled to the transmitter restores the bit to a pre-inversion value.

System and method for controlling peak to average power ratio

A digital pre-distortion component includes: a first capturing component that captures a first sample set of data; a first generating component that generates a first change matrix associated with a portion of the first sample set of data; a first memory component that stores the first change matrix; a second capturing component that captures a second sample set of data; a second generating component that generates a second change matrix associated with a portion of the second sample set of data; a second memory component that stores the second change matrix; a third capturing component that captures a third sample set of data; a third generating component that generates a third change matrix associated with a portion of the third sample set of data; a comparing component that compares the third change matrix with the first change matrix to obtain a first comparison, and compares the third change matrix with the second change matrix to obtain a second comparison; and an adapting component that adapts the digital pre-distortion component with the third sample set of data based on one of the first comparison and the second comparison.

Capture selection for digital pre-distortion adaptation and capture concatenation for frequency hopping pre-distortion adaptation

Example embodiment of the systems and methods of linear impairment modeling to improve digital pre-distortion adaptation performance includes a DPD module that is modified during each sample by a DPD adaptation engine. A linear impairment modeling module separates the linear and non-linear errors introduced in the power amplifier. The linear impairment model is adjusted during each sample using inputs from the input signal and from a FB post processing module. The linear impairment modeling module removes the linear errors such that the DPD adaptation engine only adapts the DPD module based on the non-linear errors. This increases system stability and allows for the correction of IQ imbalance inside the linear impairment modeling, simplifying the feedback post-processing.

Subtracting linear impairments for non-linear impairment digital pre-distortion error signal

A method of predistorting an input signal () for an amplifier is disclosed (FIG.). The method includes predistorting the input signal with a first set of parameters (FDPD) and a second set of parameters (CDPD) at a first time (). The first set of parameters is updated at a second time (). The second set of parameters is updated separately from the first set of parameters at a third time ().

Dual loop digital predistortion for power amplifiers

Transmitter first/second digital predistortion and first/second adaption circuitry with feedback

A method to form a CFR cancellation filter for signals with dynamic power and frequency distribution by estimating the filter at the rate required by the input signal's dynamics. For mixed mode systems (for example CDMA and LTE) the CFR is computed for each stream, and combined to form the final filter.

Crest factor reduction for signals with dynamic power and frequency distribution

This invention is a method of power amplifier digital pre-distortion which measures a current power level of the power amplifier, stores in a look up table entries consisting of a power level and a corresponding set of digital pre-distortion coefficients, selects a set of digital pre-distortion coefficients corresponding to the measured power level. If the measured current power level is near a power level index, the digital pre-distortion coefficients correspond to the power level index. If the measured current power level is greater than the maximum power level entry, the digital pre-distortion coefficients is of the maximum power level entry. If the measured current power level is less than the minimum power level entry, the digital pre-distortion is of the minimum power level entry. If the measured current power level is not near a power level index, the digital pre-distortion coefficients are an interpolation.

Power-indexed look-up table design of digital pre-distortion for power amplifiers with dynamic nonlinearities

Traditionally, for multi-band communication systems, independent signal chains for each of the different bands are employed. By using such an architecture, there are a large number of components, and there is substantial power consumption. Here, transmit processor is provided that enables transmission across multiple bands using few components (namely, fewer signal chains), while also provided for digital predistortion.

Multi-band power amplifier digital predistortion system and method

In conventional radio frequency (RF) systems, transmitters will usually convert baseband signals to RF so as to be transmitted. As part of the conversion process, the transmitters will perform digital predistortion (DPD), which uses feedback from a power amplifier. However, there are usually mismatches between the in-phase (I) and quadrature (Q) paths within with feedback loop. Traditional IQ correction filters were ineffective at providing adequate compensation for these mismatches, but here a filter is provided that provides adequate out-of-band compensation by use of frequency selectivity.

Frequency selective IQ correction

Crest factor reduction algorithms described herein may be used to improve power amplifier efficiency during low signal power conditions compared to traditional static threshold techniques. Techniques described herein insure that the signal power level at the output of the crest fact reduction block is held constant relative to the input power level under all signal power level conditions. Two different solutions may be implemented together or separately to achieve the desired conditions. The first technique provides constant ratio between input power and output power. Constant ratio of peak and average output levels keeps the amount of crest factor reduction applied to the signal constant, irrespective of the signal power level. A second technique is to hold signal power level constant in respect to the amount of crest factor reduction applied.

Systems and methods of improved power amplifier efficiency through adjustments in crest factor reduction

An apparatus and system are provided for crest factor reduction (CFR). Preferably, a peak from the wideband signal is detected. A gain from the magnitude of the peak and a threshold can then be calculated. Based on this information, each carrier's contribution to the peak can be approximated, and a cancellation pulse coefficient for each carrier from its contribution to the peak can be calculated. A base cancellation pulse can be calculated from the cancellation pulse coefficients for each carrier, and a cancellation pulse can be calculated from the base cancellation pulse and the gain, which can then be applied to the wideband signal.

Method and system for crest factor reduction

Conventional transceivers do provide some compensation for in-phase/quadrature (I/Q) imbalance. However, these techniques do not separately compensate for I/Q imbalance for the transmitter and receiver sides of the transceiver. Here, a transceiver is provided that allows for compensation of I/Q imbalance in the transmitter and receiver irrespective of the other to allow for a more accurate transceiver.

Joint transmit and receive I/Q imbalance compensation

An apparatus is provided. In the apparatus, an input to index (I2I) module maps a complex input into a real signal. A real data tap delay line is coupled to the I2I module and includes N delay-elements. A complex data tap delay line is configured to receive the complex input and includes M delay elements. A set of K of non-linear function modules is also provided. Each non-linear function module from the set has at least one real input, at least one complex input, and at least one complex output. A configurable connectivity crossbar multiplexer couples K of the N real tap delay line elements to real inputs of the set non-linear functions and couples K of the M complex tap delay line elements to complex inputs of the set non-linear function modules.

Systems and methods of power amplifier digital pre-distortion

A method of wireless handover in a broadcast network (FIGS.and) is disclosed. A wireless receiver (FIG.) receives a first signal (N) from a first transmitter (f). The receiver measures a signal strength (RSSI) of the first signal. The strength of the first signal is compared to a first threshold (T). The receiver receives a second signal (N+3) from a second transmitter (f) in response to the step of comparing. The first and the second signals are sent to an application processor (). The wireless receiver continues to receive the first and second signals until the application processor terminates receiving one of the first and second signals.

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Plano, TX, United States of America

Zigang Yang