CDMA TRANSMITTER HAVING DIGITAL TRANSMIT GAIN CONTROLLER

摘要

PURPOSE: A CDMA transmitter having a digital transmit gain controller is provided to exclude a gain controller's characteristic variation problem based on variation of temperature and to precisely carry out transmit gain adjustment. CONSTITUTION: A CDMA transmitter having a digital transmit gain controller(201) is comprised of the digital transmit gain controller(201), a D/A converter(202), a distortion amplifier(203), a direct conversion QPSK(Quadrature Phase Shift Keying) modulator(204), and an RF amplifier(205). The digital transmit gain controller(201) receives a digital baseband I/Q signal and executes transmit gain adjustment. The D/A converter(202) receives the output signal of the digital transmit gain controller(201) and converts it into an analog signal. The distortion amplifier(203) receives the converted analog signal and executes distortion amplification by a nonlinear characteristic. The direct conversion QPSK modulator(204) modulates the distortion-amplified signal into an RF signal. The RF amplifier(205) propagates the modulated RF signal to an antenna.