Abstract:
A predistortion circuit is for providing distortion correction in a presence of harmonics. The predistortion circuit includes an input for receiving a digital input signal; an output for providing a digital output signal to an up-conversion element that produces harmonic terms operably coupled to a non-linear device; and a processor operably coupled to an output of the non-linear device for receiving an output radio frequency signal therefrom and arranged to determine a digital correction to be applied to the digital input signal. The processor is further arranged to determine the digital correction that includes a plurality of in-phase and quadrature cross-terms of the digital input signal where terms of a same order have different co-efficients.
Abstract:
A transmitter that uses a digital pre-distortion (DPD) circuit to mitigate the effects of nonlinearity of a multistage or multi-branch power amplifier. The DPD circuit relies on two or more feedback signals received from an RF-output circuit of the transmitter to generate individually pre-distorted signals for the individual stages/branches of the power amplifier. The use of these individually pre-distorted signals advantageously enables the transmitter to achieve a more efficient suppression of inter-modulation-distortion products than that typically achieved with a comparable prior-art transmitter.
Abstract:
The presented invention discloses a system for nonlinear transfer function compensation of high power amplifiers especially in the case of wideband signal transmission. According to the presented invention the input signal comprising an inphase and quadrature component of an arbitrary modulated digital baseband signal is predistorted in predistortion circuitry and converted form baseband to the radiofrequency band. After digital to analog conversion the analog signal is further processed with shaping filter and amplified by high power amplifier. Predistortion of complex baseband signal is based on a process of splitting the input signal into upper and lower sideband. The individual bands are independently predistorted with complex multiplication with coefficients stored in two independent memories. Selection of the coefficient is based on the instantaneous power of the total input signal. Inphase and quadrature components of the upper and lower sidebands are pairwise summed into inphase and quadrature component of output predistorted signal.
Abstract:
Disclosed is a transceiver for an envelope following system that includes a power amplifier (PA) having a signal input, a signal output, and a power input that receives power from a power management system that modulates a supply voltage provided to the PA in response to an envelope signal. The transceiver includes a calibration subsystem that is adapted to provide a first test signal to the signal input of the PA and to provide a second test signal to the power management system in place of the envelope signal. The calibration subsystem is programmed with calibration methods that sweep the first test signal through a first range and to sweep the second test signal through a second range in order to derive values that make up a pseudo-envelope look-up table (LUT) that is usable by the transceiver.
Abstract:
A system and method for remotely monitoring, communicating with, and reconfiguring power amplifier systems. A communications link is provided in field- deployed PA systems, for enabling remote communication with appropriate digital components such as microprocessors or other communications-capable portions of the power amplifier systems. The communications link permits operating parameters of the PA to be monitored and sent back to a remote terminal such as a web server or other computer mainframes via any suitable wired or wireless connection including internet, Ethernet, wireless, WiFi, WiMAX, cellular, local area networks (LAN), wide area networks (WAN), Bluetooth, and so forth. The communication is bi-directional, so that the remote host can download to the PA updates, cMobile operators and/or other service providers can reduce significant operating and capital expenses related to their radio networks maintenance and PA replacement by practicing this invention.
Abstract:
A Volterra series-based digital pre-distorter for RF power amplifiers combines look-up-tables and multiplication, along with time division multiplexing to reduce the hardware resources required for implementation.
Abstract:
A baseband-derived RF predistortion system using a lookup table having coefficients extracted at baseband and then applied at RF by means of a vector modulator. The architecture combines the narrowband advantage of envelope predistortion with the accuracy of baseband predistortion, and including compensation for memory effects. A polynomial-based alternative is also described.
Abstract:
Predistorting an input signal prior to amplification in an RF power amplifier (206) includes isolating a plurality sub-band signals, each representing a portion of the input signal s(t). The method includes independently modifying an amplitude and a phase of each of the plurality of sub-band signals. The modification of the amplitude and/or phase is performed using a set of signal weighting parameters (weights) w and W, controlling linear and nonlinear modifications respectively, which are determined in an adaptive process by an adaptive controller (224). After modification, each of the sub-bands are summed together to obtain a predistorted input signal for an RF power amplifier (206).