Patent ID: 7777546

Claim:
A DC offset calibration apparatus comprising: a first adjustment unit, for receiving a first input signal and a first offset calibration signal and for adjusting the first input signal to generate a first output signal according to the first offset calibration signal; a first offset calibration circuit, coupled to the first output signal and the first adjustment unit, for determining the first offset calibration signal according to the first output signal and at least one predetermined threshold value, the first offset calibration circuit comprising: a first calibration circuit, coupled to the first output signal, the first calibration circuit comprising: a first comparator, for comparing the first output signal with the predetermined threshold voltage level to generate a first control signal; and a first transistor, having a first end coupled to a reference voltage, a second end coupled to the first adjustment unit, and a control end coupled to the first comparator, wherein the first control signal controls to turn on the first transistor so as to adjust the voltage level of the first offset calibration signal; a second adjustment unit, for receiving a second input signal and a second offset calibration signal and for adjusting the second input signal to generate a second output signal according to the second offset calibration signal; and a second offset calibration circuit, coupled to the second output signal and the second adjustment unit, for determining the second offset calibration signal according to the second output signal and the predetermined threshold value, the second offset calibration circuit comprising: a second calibration circuit, coupled to the second output signal, the second calibration circuit comprising: a second comparator, for comparing the second output signal with the predetermined threshold voltage level to generate a second control signal; and a second transistor, having a first end coupled to the reference voltage level, a second end coupled to the second adjustment unit, and a control end coupled to the second comparator, wherein the second control signal controls to turn on the second transistor so as to adjust the voltage level of the second offset calibration signal; wherein the first input signal and the second input signal are a differential signal pair.