Abstract: A transceiver for a wireless communication system is provided. The transceiver includes a transmit path and a receive path. Further, the transceiver includes a loopback path operatively coupled between the transmit path and the receive path. The loopback path includes only passive elements for processing radio frequency signals, and no external energy source may contribute to a magnitude of the element's output. Accordingly, the loopback path may prevent the transmit path to the receive path leakage via a common supply or ground plane.

Abstract: A communication device is provided that includes a modulation circuit configured to modulate a signal comprising a first signal portion of a first data type and a second signal portion of a second data type. The modulation circuit is configured to modulate the first signal portion in accordance with a first modulation scheme and the second signal portion in accordance with a second modulation scheme. At least one of the first data type is different from the second data type or the second modulation scheme is different from the first modulation scheme. The communication device further includes a modification circuit configured to modify the modulated first signal portion based on a first modification scheme and the second signal portion based on a second modification scheme. The communication device further includes a transmitter configured to transmit the modified first signal portion and the modified second signal portion.

Abstract: A method for predistorting an input signal of an amplifier device comprises evaluating a selection criterion for a computational model of the amplifier device. The computational model provides an output signal of the amplifier device for the input signal of the amplifier device. Further, the method comprises selecting between a first computational model of the amplifier device and a second computational model of the amplifier device based on the evaluated selection criterion. Additionally, the method comprises predistorting the input signal of the amplifier device using the selected computational model.

Abstract: A communication device is provided that includes a modulation circuit configured to modulate a signal comprising a first signal portion of a first data type and a second signal portion of a second data type. The modulation circuit is configured to modulate the first signal portion in accordance with a first modulation scheme and the second signal portion in accordance with a second modulation scheme. At least one of the first data type is different from the second data type or the second modulation scheme is different from the first modulation scheme. The communication device further includes a modification circuit configured to modify the modulated first signal portion based on a first modification scheme and the second signal portion based on a second modification scheme. The communication device further includes a transmitter configured to transmit the modified first signal portion and the modified second signal portion.

Abstract: An apparatus to apply frequency selective digital predistortion (DPD) to a power amplifier (PA) circuit is disclosed. The apparatus comprises a first transformation circuit configured to receive a PA input comprising a quantity indicative of an input signal of the PA circuit and process the PA input by applying a first predetermined weighted function, to form a processed PA input, and a second transformation circuit configured to receive a PA output comprising a quantity indicative of an output signal of the PA circuit and process the PA output by applying a second predetermined weighted function, to form a processed PA output. The apparatus further comprises a coefficient computation circuit configured to receive the processed PA input and the processed PA output; and estimate distortion coefficients, to be utilized for predistorting the input signal of the PA circuit, based on the processed PA input and the processed PA output.

Abstract: An adaptive controller for a nonlinear system includes a Volterra filter having a transfer function defined by P coefficients. The controller includes an alignment/compensation circuit, which aligns the input samples to the output samples of the nonlinear system. The controller generates a P×P matrix using at least one of input samples to, or output samples from the nonlinear system and normalizes each element of the P×P matrix using a respective normalization factor. The controller generates and solves a system of P linear equations from the P×P matrix and a P×1 matrix derived from input and output samples of the nonlinear system using Cholesky decomposition that may include Fast Inverse Square Root operations and forward backward elimination to generate P values. The controller multiplies each of the P values by an inverse of a respective one of the normalization factors to generate the P coefficients for the Volterra filter.

Abstract: Techniques for compensating for signal impairments introduced by a mixer are discussed. One example system employing such techniques can include mixer predistortion circuitry configured to receive signal in-phase (I) and signal quadrature (Q) components of a signal and to generate a mixer predistortion signal based at least in part on the signal I and Q components, wherein the mixer predistortion signal compensates for nonlinearities caused by a mixer that upconverts the signal. Optionally, imbalance correction circuitry to compensate for gain and phase imbalance and/or skew correction circuitry to compensate for gain and phase skew can also be included.

Abstract: Techniques for compensating for signal impairments introduced by a mixer are discussed. One example system employing such techniques can include mixer predistortion circuitry configured to receive signal in-phase (I) and signal quadrature (Q) components of a signal and to generate a mixer predistortion signal based at least in part on the signal I and Q components, wherein the mixer predistortion signal compensates for nonlinearities caused by a mixer that upconverts the signal. Optionally, imbalance correction circuitry to compensate for gain and phase imbalance and/or skew correction circuitry to compensate for gain and phase skew can also be included.

Abstract: Techniques for compensating for signal impairments introduced by a mixer are discussed. One example system employing such techniques can include mixer predistortion circuitry configured to receive signal in-phase (I) and signal quadrature (Q) components of a signal and to generate a mixer predistortion signal based at least in part on the signal I and Q components, wherein the mixer predistortion signal compensates for nonlinearities caused by a mixer that upconverts the signal. Optionally, imbalance correction circuitry to compensate for gain and phase imbalance and/or skew correction circuitry to compensate for gain and phase skew can also be included.