Circuit and method for DC offset calibration and signal processing apparatus using the same

Signal processing apparatus comprising:

• a LNA 331;
• a mixer 333 for mixing the output from said LNA 331 with local oscillation signal LO;
• a first variable gain amplifier 337 for amplifying output from said LNA 331 while controlling the gain thereof;
• means connected to output of said first variable gain amplifier 337 for eliminating DC components in the output from said first variable gain amplifier 337;
• an offset correction amplifier 339 for amplifying output from said means for eliminating DC offset in the output in accordance with a first control signal;
• a second variable gain amplifier 341 for amplifying output from said offset correction amplifier 339 while controlling the gain thereof;
• offset calibration mean 343 for calibrating DC offset in output from said second variable gain amplifier 341;
• and
• offset correction mean 345 for outputting the control signal in accordance with output from said offset calibration mean 343, to eliminate DC offset in the output from said variable gain amplifier 341.

Signal processing apparatus comprising:

• an offset correction amplifier for amplifying signals received to first and second input terminal differentially to output through first and second output terminals, respectively, and for eliminating DC offset in the received signals in accordance with a offset control signal;
• a variable gain amplifier for amplifying output of said offset correction amplifier while controlling gain thereof;
• offset calibration means for calibrating DC offset in output from said variable gain amplifier;
• and
• offset correction means for outputting the offset control signal for correcting DC offset calibrated by said offset calibration means.

Method for correcting DC offset in a signal processing apparatus comprising steps of:

• activating the signal processing apparatus;
• setting initial data for correcting DC offset;
• sensing whether either frequency of PLL or cutoff frequency of LPF is changed;
• correcting DC offset, when a change is sensed in the sensing step, and determining the correction data from MSBs to LSBs n a successive approximation method;
• and
• correcting DC offset, when a change is not sensed in the sensing step or the correcting step is completed, by calibrating DC offset in a real time base and increasing or decreasing the correction data pursuant to the calibrated DC offset.

Method for correcting DC offset in a signal processing apparatus comprising steps of:

• activating the signal processing apparatus;
• setting initial data for correcting DC offset;
• correcting DC offset and determining the correction data from MSBs to LSBs n a successive approximation method;
• and
• correcting DC offset by calibrating DC offset in a real time base and increasing or decreasing the correction data pursuant to the calibrated DC offset.