Patent ID: 7636405

Claim:
A method for calibrating in-phase and quadrature-phase (IQ) mismatch in a direct down-conversion circuit of a communication system, the method comprising: generating an in-phase analog signal and a quadrature-phase analog signal according to an RF signal, utilizing a first mixer and a second mixer, respectively; generating, with a first sampling circuit, a first reference signal according to the in-phase analog signal; generating, with a second sampling circuit, a second reference signal according to the quadrature-phase signal; delaying the first reference signal by a predetermined period utilizing a delay circuit, and thus generating a first delay signal; generating, with a synthesizing device, a synthesized signal according to the first delay signal and the second reference signal; executing, with an algorithm operation device, a predetermined algorithm on the synthesized signal, the first reference signal, and the first delay signal to thereby output a compensation signal; wherein executing the predetermined algorithm further comprises executing a least mean squares (LMS) algorithm on the synthesized signal, the first reference signal, and the first delay signal according to an error threshold limit value, so as to thereby output the compensation signal; and utilizing a calibrating device for calibrating IQ mismatch between the in-phase analog signal and the quadrature-phase analog signal according to the compensation signal.