Abstract: A method and base station transmitter for providing offline tuning of a base station transmitter. The base station transmitter includes a feed-forward power amplifier comprising a Radio Frequency (RF) input and an RF output. The base station transmitter also includes a simulated carrier generator operatively coupled to the feed-forward power amplifier prior to the carrier cancellation loop. The simulated carrier generator provides a simulated carrier signal including one or more individual carrier frequencies to the RF input. The base station transmitter also includes a processor that is operatively coupled to the feed-forward power amplifier and the simulated carrier generator. The processor performs tuning of a carrier cancellation loop using the simulated carrier signal when the processor determines that a carrier signal is not present.

Abstract: A linear transmitter includes a closed loop feedback path to maintain linearity of a power amplifier subsystem. The closed loop feedback path provides RF injection of one or more reference RF carrier signals (172, 174) combined with a radio frequency (RF) feedback signal (149) to generate a feedback RF error signal (173). A narrowband receiver (170) continuously monitors stability of the feedback RF error signal (173). A loop phase adjusting circuit (188) generates phase adjustments (189) to compensate for instabilities in the closed loop feedback path thereby maintaining stability of the PA RF output signal (146).

Abstract: A ceiling value can be established (505) for a sum of peak power for a first baseband signal (330) and a second baseband signal (332). No correlation needs to exist between the power peaks of the baseband signals (330, 332). A detection can occur (510) indicating that a sum of the baseband signals (330, 332) has a peak power exceeding the ceiling value. This detection can result in modifications of both the first baseband signal and the second baseband signals. Each is modified by: first modifying each signal so that the sum of the signals is less than the ceiling value (515), to filter the results with a root raised cosine function (520), to window clip the filtered results (525), and to filter the clipped results using a root raised cosine filter (525).

Abstract: A ceiling value can be established (505) for a sum of peak power for a first baseband signal (330) and a second baseband signal (332). No correlation needs to exist between the power peaks of the baseband signals (330, 332). A detection can occur (510) indicating that a sum of the baseband signals (330, 332) has a peak power exceeding the ceiling value. This detection can result in modifications of both the first baseband signal and the second baseband signals. Each is modified by: first modifying each signal so that the sum of the signals is less than the ceiling value (515), to filter the results with a root raised cosine function (520), to window clip the filtered results (525), and to filter the clipped results using a root raised cosine filter (525).

Abstract: A linear transmitter includes a closed loop feedback path to maintain linearity of a power amplifier subsystem. The closed loop feedback path provides RF injection of one or more reference RF carrier signals (172, 174) combined with a radio frequency (RF) feedback signal (149) to generate a feedback RF error signal (173). A narrowband receiver (170) continuously monitors stability of the feedback RF error signal (173). A loop phase adjusting circuit (188) generates phase adjustments (189) to compensate for instabilities in the closed loop feedback path thereby maintaining stability of the PA RF output signal (146).

Abstract: A communication device having an RF power amplifier stage with a Cartesian feedback loop is provided. The loop has forward paths whose outputs are combined to form an output signal that is fed back to a single feedback path. Each forward path has a common path with a filter that filters the overall loop response and a unique split path. The main and auxiliary split paths have a power amplifier and carry signals respectively of lower and higher frequencies. The auxiliary amplifier is faster than the main amplifier. Different phases of the carrier signal are used during upconversion such that the overall phase response through the split paths is equal. Instability recovery problems introduced by higher-order loop filters are mitigated by baseband loop filters with switchable order. Upon detecting instability, the loop filter order is reduced and is subsequently increased after eliminating the unstable operation.

Abstract: A power amplifier module and corresponding system for linearizing the output from a power amplifier includes both a feedback system, containing a compensator and the power amplifier in a feedback loop, and a pre-distortion compensation system injecting pre-distortion signals into or before the feedback system are used to compensate for non-linearities in the overall system. The pre-distortion signals may be mixed with signals from the compensator or may be filtered to take into account the loop compensator transfer function of the feedback loop, mixed with baseband signals and then converted into analog signals that are provided to the feedback loop. In modules containing a tracking power supply, an envelope calculator calculates an RF envelope of the baseband signals, which the pre-distortion system uses in conjunction with the baseband signals to generate the pre-distortion signals mixed with the signals from the compensator.

Abstract: A communication device having an RF power amplifier stage with a Cartesian feedback loop is provided. The loop has forward paths whose outputs are combined to form an output signal that is fed back to a single feedback path. Each forward path has a common path with a filter that filters the overall loop response and a unique split path. The main and auxiliary split paths have a power amplifier and carry signals respectively of lower and higher frequencies. The auxiliary amplifier is faster than the main amplifier. Different phases of the carrier signal are used during upconversion such that the overall phase response through the split paths is equal. Instability recovery problems introduced by higher-order loop filters are mitigated by baseband loop filters with switchable order. Upon detecting instability, the loop filter order is reduced and is subsequently increased after eliminating the unstable operation.

Abstract: A power amplifier module and corresponding system are disclosed for linearizing the output from a power amplifier. Both a feedback system, containing a compensator and the power amplifier in a feedback loop, and a pre-distortion compensation system injecting pre-distortion signals into or before the feedback system are used to compensate for non-linearities in the overall system. The pre-distortion signals may be mixed with signals from the compensator or may be filtered to take into account the loop compensator transfer function of the feedback loop, mixed with baseband signals and then converted into analog signals that are provided to the feedback loop. In modules containing a tracking power supply, an envelope calculator calculates an RF envelope of the baseband signals, which the pre-distortion system uses in conjunction with the baseband signals to generate the pre-distortion signals mixed with the signals from the compensator.