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rate of up to 14 Mbits/s. The universal mobile telecommunications system This paper overviews the universal mobile telecommu-(UMTS) long term evolution (LTE) system, also known as nications system long term evolution (LTE) and discusses the 3.9G, is currently under standardization aiming at the smooth requirements for device technologies pertaining to mobile migration towards the next generation. A peak data rate over terminals. The LTE represents the next generation cellular 100 Mbits/s for the DL and 50 Mbits/s for the uplink (UL) phone technology that is intended to achieve a high peak with low latency are the key requirements for this system. data rate, low latency, and high radio efficiency in addition to This system is summarized in the following sections. low cost and sufficiently high mobility characteristics. Vigorous discussion regarding the specifications for LTE is curTable

Design and performance of a novel power amplifier, Linearized S a t u r a t i o n Amplifier w i t h Bidirectional Control(LSA-BC), are presented. A linear amplifier with the high efficiency of a switching-mode saturation amplifier can be realized. A high efficiency GaAs F E T is roughly linearized by dynamically varying its drain DC voltage with a high efficiency variable output DC-DC converter. I n addition, a negative envelope feed-back i s utilized to compensate for the residual. The circuit construction is simple enough for use in the portable subscriber units of a digital mobile radio system. A 1.5 GHz band 1 W LSA-BC is constructed to determine its performance with 32kbps roll-off QPSK. As a result, a 40% total efficiency is achieved as well as a stable 3rd-order intermodulation distortion of -50 dB to the signal level.

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