| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus and a method for calibrating the frequency of a local oscillator in wireless communications. SOLUTION: According to a disclosed embodiment, a receiver comprising a digital rotator in combination with a frequency error discriminator in a digital automatic frequency control loop is used to obtain accurate digital values used to calibrate a local oscillation frequency. A frequency error in the oscillation frequency of a local frequency generation loop causes a change in the frequency of a baseband input signal. The change in the baseband input signal frequency related to the frequency error in the local frequency generation loop can be detected as a phase rotation by the frequency error discriminator. By using the digital automatic frequency control loop, the frequency error introduced by local frequency generation is determined with accuracy. The frequency error and corresponding control bits are entered into a calibration table. The calibration table may be used to adjust the local oscillation frequency for temperature changes, pilot searching, and quick paging. COPYRIGHT: (C)2010,JPO&INPIT |
