Patent ID: 7551904
Filing Date: 2009-06-23
Classification: H03F

Abstract:
1. An apparatus for power amplification in a mobile communication system, the apparatus comprising: a Low Pass Delta-Sigma Modulator (LPDSM) for receiving baseband signals from a baseband-side and modulating the received baseband signals into oversampled baseband digital signals; an IQ modulator for receiving the oversampled baseband digital signals output from the LPDSM and generating signals having a constant envelope by IQ-modulating the oversampled baseband digital signals; an up-converter for up-converting the constant envelope signals to Radio Frequency (RF) signals; and a power amplifier for amplifying the RF signals according to system setup levels and outputting the amplified RF signals having a constant envelope of a predetermined level, wherein the baseband signals are oversampled below a carrier frequency and the oversampled baseband digital signals are I and Q complex data signals having a constant amplitude and the IQ modulator generates the constant envelope signals using a modulation scheme based on Quadrature Phase Shift Keying (QPSK) modulation.