포락선 추적 기술을 응용한 고효율 전력 증폭기에 관한 연구
- 포락선 추적 기술을 응용한 고효율 전력 증폭기에 관한 연구
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- As the wireless communication systems evolve, requirements of base-station RF power amplifiers (PAs) are increasingly demanding. In addition, RF PAs in the transmitter should transfer the signals which handle huge data and wide bandwidth, thus, high efficiency and wideband characteristics are required for base-station. This study proposes various design methods of the inverted Doherty power amplifiers (IDPAs) with unsymmetrical delay path
high-efficiency inverse class-E PA with envelope tracking (ET) technique and digital predistortion (DPD) linearization
and the wideband distributed amplifier employing ET technique.For high efficiency, DPA and IDPA structures have been widely applied to the PAs due to its efficiency characteristics. Because they show the peak efficiency at a large back-off power (BOP) from the saturation power and have several advantages of simple circuitry and easy implementation. But the phase difference between the carrier and peaking PAs cause degradation of efficiency and linearity. In this study, the IDPA with unsymmetrical delay path inserting an input offset line at the input path of the carrier PA is presented to compensate for the phase difference. Switching-mode PAs (SMPAs) have been also widely investigated as the powerful method of improving efficiency as DPA and IDPA structures. Among various SMPAs, the inverse class-E PA is recently reported because it shows high efficiency performance and has the merit of operating with lower peak voltage than the class-E PA. However, the internal parasitic components of the packaged transistor in the inverse class-E topology disturb the maximum efficient operation. So, the ways to compensate there drawbacks should be required. Here, the inverse class-E PA which uses the shunt inductor compensating the parasitic large output capacitance of the packaged transistor is presented, where double composite right/left handed-transmission lines are used for high efficiency. Also, the ET technique and DPD linearization are used for achieving higher efficiency and good linearity.As the bandwidth of signals expands, wideband characteristics of PAs are necessary. For wideband characteristics, many methods such as modified DPAs, modified SMPAs, and distributed PAs have been developed and suggested. Among them, the distributed PA with ultra-wide bandwidth has been widely reported for wideband performance because it provides an ultra-wide bandwidth. However, the distributed PA has a fatal defect such as low efficiency and low power. This work has been proposed a wideband distributed PA employing an ET technique, which shows high efficiency as well as wideband characteristics. The highly efficient inverted DPA with unsymmetrical delay path, the high efficiency inverse class-E PA with ET technique, and a wideband distributed PA employing an ET technique have been presented, it is evident that the proposed methods can be a valuable guideline to design the PAs with high efficiency and wideband characteristics.
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