Abstract:
A digital-to-analog converter is provided. The digital-to-analog converter includes a first plurality of digital-to-analog converter cells configured to generate a first analog signal. Further, digital-to-analog converter includes a second plurality of digital-to-analog converter cells configured to generate a second analog signal. The first analog signal and the second analog signal form a differential signal pair. Further, the digital-to-analog converter includes a transmission line transformer comprising a first input node coupled to the first plurality of digital-to-analog converter cells, a second input node coupled to the second plurality of digital-to-analog converter cells, and a first output node. The transmission line transformer is configured to present a first impedance at the first and second input nodes and to present a second impedance at the first output node.
Abstract:
Software Digital Front End (SoftDFE) signal processing techniques are provided. One or more digital front end (DFE) functions are performed on a signal in software by executing one or more specialized instructions on a processor to perform the one or more digital front end (DFE) functions on the signal, wherein the processor has an instruction set comprised of one or more of linear and non-linear instructions. A block of samples comprised of a plurality of data samples is optionally formed and the digital front end (DFE) functions are performed on the block of samples. The specialized instructions can include a vector convolution function, a complex exponential function, an xk function, a vector compare instruction, a vector max( ) instruction, a vector multiplication instruction, a vector addition instruction, a vector sqrt( ) instruction, a vector 1/x instruction, and a user-defined non-linear instruction.
Abstract:
Maximum likelihood bit-stream generation and detection techniques are provided using the M-algorithm and Infinite Impulse Response (IIR) filtering. The M-Algorithm is applied to a target input signal X to perform Maximum Likelihood Sequence Estimation on the target input signal X to produce a digital bit stream B, such that after filtering by an IIR filter, the produced digital stream Y produces an error signal satisfying one or more predefined requirements. The predefined requirements comprise, for example, a substantially minimum error. In an exemplary bit detection implementation, the target input signal X comprises an observed analog signal and the produced digital stream Y comprises a digitized output of a receive channel corresponding to a transmitted bit stream. In an exemplary bit stream generation implementation, the target input signal X comprises a desired transmit signal and the produced digital stream Y comprises an estimate of the desired transmit signal.
Abstract:
Methods and apparatus are provided for direct synthesis of RF signals using maximum likelihood sequence estimation. An RF digital RF input signal is synthesized by performing maximum likelihood sequence estimation on the digital RF input signal to produce a digital stream, such that after filtering by a prototype filter the produced digital stream produces a substantially minimum error. The substantially minimum error comprises a difference between a digital output of the prototype filter and the digital RF input signal. The digital stream is substantially equal to the input digital RF signal. The digital stream can be applied to an analog restitution filter, and the output of the analog restitution filter comprises an analog RF signal that approximates the digital RF input signal.
Abstract:
A processor is provided having an instruction set with a sliding window non-linear convolution function. A processor obtains a software instruction that performs a non-linear convolution function for a plurality of input delayed signal samples. In response to the software instruction for the non-linear convolution function, the processor generates a weighted sum of two or more of the input delayed signal samples, wherein the weighted sum comprises a plurality of variable coefficients defined as a sum of one or more non-linear functions of a magnitude of the input delayed signal samples; and repeats the generating step for at least one time-shifted version of the input delayed signal samples to compute a plurality of consecutive outputs. The software instruction for the non-linear convolution function is optionally part of an instruction set of the processor. The non-linear convolution function can model a non-linear system with memory, such as a power amplifier model and/or a digital pre-distortion function.
Abstract:
Methods and apparatus are provided for non-linear modeling of a physical system using look-up tables with polynomial interpolation. A non-linear function is evaluated for a complex input value by obtaining at least one look-up table with polynomial interpolation that represents the non-linear function, wherein entries in the look-up table comprise polynomial coefficients of at least degree two for different segments of the non-linear function; obtaining a point from the look-up table that is near a magnitude of the complex input value; and generating a complex output value by evaluating the polynomial coefficients at the point to perform a Taylor Series expansion from said point. The non-linear function characterizes, for example, a power amplifier or an inverse of a power amplifier and the look-up tables can be used, for example, to implement digital pre-distortion.
Abstract:
A processing device is provided. The processing device comprises one or more interfaces configured to transmit information to a nonlinear device and processing circuitry configured to control the one or more interfaces and to. Further, the processing circuitry is configured to transmit an excitation signal to the nonlinear device and to receive response information from the nonlinear device. Further, the processing circuitry is configured to determine a linear response of the nonlinear device based on the response information and to determine a nonlinear response of the nonlinear device based on the determined linear response.
Abstract:
A semiconductor device comprising at least one transmit path is provided. The transmit path comprises an input node for receiving a digital baseband signal. Further, the transmit path comprises digital mixer circuitry coupled to the input node and configured to generate an upconverted digital baseband signal by upconverting a frequency of the digital baseband signal. Additionally, the transmit path comprises Digital-to-Analog Converter (DAC) circuitry coupled to the digital mixer circuitry and configured to generate an analog radio frequency signal based on the upconverted digital baseband signal. The transmit path comprises first analog mixer circuitry coupleable to an output of the DAC circuitry, and second analog mixer circuitry coupleable to the output of the DAC circuitry. Further, the transmit path comprises a first output node coupleable to an output of the first analog mixer circuitry, and a second output node coupleable to an output of the second analog mixer circuitry.
Abstract:
A wireless communication system including a phased array comprising a plurality of antennas configured to emit a respective radio wave based on a respective antenna signal. Further, the system includes a plurality of power amplifiers each coupled to one of the plurality of antennas via a feed line and configured to output the antenna signal to the feed line. Also, the system includes a plurality of directional couplers each coupled into one of the feed lines and comprising a third port configured to output a fraction of a power received at a first port coupled to the power amplifier via the feed line, likewise a fourth port configured to output a fraction of a power received at a second port. Additionally, the system includes switching circuitry configured to alternately couple the third port to a first feedback receiver, and to alternately couple the fourth port to a second feedback receiver.
Abstract:
Techniques are disclosed for the use of a hybrid architecture that combines a programmable processing array and a hardware accelerator. The hybrid architecture functions to maintain synchronization between data samples to be transmitted, feedback data samples measured from an observed previous transmission of data samples, and output data samples that comprise the data samples from previous data transmissions, which may include data samples prior to or after the application of DPD terms. The architecture enables synchronization amongst several transmission channels, and provides for high flexibility with respect to timing flows and the movement and processing of data blocks.