A major drawback of Orthogonal Frequency Division Multiplexing (OFDM) signals is extremely high Peak-to-Average Power Ratio (PAPR). Signals with high PAPR lead to a lowering of the energy efficiency of the Power Amplifiers (PAs) and the shortened operation time causes a serious problem in battery-powered wireless terminals. In this paper, we propose a new power saving technique for wireless terminals. It is the combination of a polar modulation technique and Constant Amplitude Zero Auto-Correlation (CAZAC) equalizing technique. Proposed the polar modulation technique for the PA employs a current control by changing the common-gate stage bias in a cascade amplifier circuit. The CAZAC equalization scheme makes the PAPR of M-array Quadrature Amplitude Modulation (M-QAM) OFDM signals into the PAPR of M-QAM single-carrier signals. By using CAZAC-OFDM signal, proposed polar modulation PA exhibits overall efficiency of 40% at Error Vector Magnitude (EVM) of -32dB. Furthermore, a breakthrough technique which transcends barrier of 50% efficiency has been proposed. A prototype of Single Ended Push-Pull amplifier (SEPP AMP) exhibits power gain of 15dB over 1OOMHz to 1GHz, the maximum efficiency of 65% without polar modulation scheme.
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