An adaptive feedforward amplifier under "Maximum Output" control method for UMTS downlink transmitters

Energy saving power amplifier design methodologies for mobile wireless communications

“…A possible solution for the above mentioned constraint is to use an adaptive control system to control the amplitude and phase response of the correction signal. This adaptive control system is realized with the aid of a digital controller [11][12][13]. The controller is responsible to generate the amplitude and phase algorithm at various operating frequencies, to ensure broadband distortion cancellation is achieved.…”

Digitally supported feed-forward harmonic cancellation for filter-less ultra-wideband transmitters

“…Therefore, traditional feed-forward scheme relies on several RF components (such as couplers, combiners, RF gain and phase shifter, RF delay line etc.). Due to rigidity, bulkiness of RF components based structure and error introduced by non-ideality of RF components, few partially DSP based implementations of feed-forward linearizer have been reported to address the flexibility and size issues ( [4] and references therein. However, they only target cancellation of intermodulation distortion (IMD) components at PA nonlinearity, which lie very near to fundamental frequency and can easily be characterized along with main signal using traditional behavioral modeling technique.…”

Improvement of Memory Effects and ACPR of Power Amplifiers in CDMA Cellular Mobile and OFDM WLAN Transmitters

“…In the Feedforward structure, the adjustment technique consists in variations of the attenuator and phase shifter and delay line located in the second loop until the third order intermodulation products of the output signal will be minimum [11][12][13][14][15][16]. First, we consider to the One-Tone test of the linearized power amplifier with commercial software Advance Design System (ADS) [17].…”