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We report a multiband Envelope-Tracking (ET) Power Amplifier (PA), comprising a very broadband RF-PA stage and a Voltage-Mode class-D (VMCD) buck-converter with 200MHz switching frequency. Both buck-converter and RF-PA were fabricated using a GaN HEMT process. High frequency switching operation of the buck-converter makes it possible to handle broadband signals (20MHz bandwidth). The design of the...
A linearization algorithm for the envelope supply voltage waveform is proposed for an open-loop multi-switcher envelope tracking power amplifier (ETPA). To maintain the fidelity of the supply voltage, we develop a two-step method comprising “non-linear pre-emphasis” and “envelope memory polynomial digital predistortion”, where the captured supply voltage of an RFPA is used. An ETPA is demonstrated...
Efficiency and linearity are important design criteria for power amplifier (PA) designers. These two constraints usually contradict each other in the realm of PAs. However, with many recent efforts, various architectures such as envelope tracking, when used in conjunction with digital pre-distortion, allow the system to achieve both efficiency and linearity simultaneously. Many of the available evaluation...
As next generation wireless communication systems move to higher data rates, the bandwidth (BW) and peak to average power ratio (PAPR) of the signal increase. Envelope tracking power amplifier systems provide a means to efficiently amplify these complex waveforms. Envelope power modulators paired with various amplifiers are presented with high efficiency and linearity‥
Envelope tracking provides the potential for achieving high efficiency in power amplifiers for next generation wireless transmitters with high peak-to-average ratio signals such as OFDMA. Envelope modulators with high fidelity, high efficiency and wide bandwidth are critical enablers for the widespread application of envelope tracking. This presentation reviews the development of various envelope...
This paper presents a high-efficiency broadband envelope-tracking power amplifier with operation at carrier frequencies from 500 to 1750 MHz. The RF power amplifier (RFPA) is provided by a single-chip gallium–nitride (GaN) integrated circuit (IC) whose design included a broadband output match achieved by operating directly into a load resistance of 50 and broadband input match achieved using...
A high efficiency wideband envelope tracking power amplifier for LTE applications is presented. The CMOS envelope amplifier with direct current sensing has a measured average efficiency of 78% with a 5 MHz LTE signal. The envelope tracking power amplifier including a GaAs HBT RF stage has overall power added efficiency (PAE) above 46% with an average LTE output power of 27.6 dBm and a gain of 26.5...
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