FREQUENCY DIRECT CONVERSION DEVICE OF A WIRELESS COMMUNICATION SYSTEM AND A METHOD THEREOF, SPECIFICALLY RELATED TO REDUCING A CARRIER FEEDTHROUGH TO IMPROVE PERFORMANCE OF THE FREQUENCY DIRECT CONVERSION DEVICE

摘要

PURPOSE: A frequency direct conversion device of a wireless communication system and a method thereof are provided to feed back a converted signal to detect DC levels of each signal, and to equalize DCs of an in-phase signal and a quadrature phase signal, thereby lowering a carrier feedthrough. CONSTITUTION: DACs(101,102) convert an in-phase signal and a quadrature phase signal into analog signals. LPFs(105,106) filter the analog signals, and extract DC components. A controller(107) detects DC sizes of the two signals outputted from the LPFs(105,106) to connect one of the signals having a higher DC to a switch(115), and connects switches(113,114) with a frequency direct converter(120) for direct conversion if DC level differences of the two signals are less than a threshold value. A comparator(108) sends the detected DC level differences, and informs the controller(107) that the DC level differences are less than the threshold value. DC supply units(103,104) apply reverse biases to an input signal as many as the DC level differences. The frequency direct converter(120) frequency direct-converts the converted two signals.