Method and apparatus for removing direct current off set in a receiver

A method and an apparatus for removing a DC offset in a receiver are provided to improve a synchronization performance and an initial block operation in the receiver by detecting the DC offset without a time delay through an FFT(Fast Fourier Transform) unit installed on a conventional OFDM receiver. An ADC(Analog-Digital Converter)(302) converts a signal which is down-converted in an RF front unit into a digital signal. A serial-parallel converter(306) receives the converted digital signal having a DC offset component, and performs a serial-parallel conversion(306). An FFT unit(308) performs FFT for the signal outputted from the serial-parallel converter(306). A DC tone detection unit(310) detects an index of a sub-carrier having a DC offset in the signal outputted from the FFT unit(308). An MUX(312) receives the index of the sub-carrier having the DC offset of the DC tone detection unit(310), and outputs a sub-carrier corresponding to the index to first and second multipliers. A calculation unit(318) calculates first and second compensation constants to estimate an original DC offset quantity extracted from the received frequency offset from a synchronization unit, and outputs the calculated result to the first and second multipliers. A first adder(314) adds outputs of the first and second multipliers, and outputs the added outputs to a second adder(320) of a rear end of the ADC(302). The second adder(320) adds and outputs the output of the first adder(314) and the output of the ADC(302).