Patent ID: 7132872

Claim:
An apparatus for adjusting a phase difference between two input signals, the apparatus comprising: a first buffer for buffering a first input signal and outputting a first output signal; a first DAC for outputting a first control voltage corresponding to a first digital value representative of a phase delay; a first variable capacitor coupled to the first DAC and the first buffer, the capacitance value of the first variable capacitor corresponding to the first control voltage; a second buffer for buffering a second input signal and outputting a second output signal; a second DAC for outputting a second control voltage corresponding to a second digital value representative of a phase delay; and a second variable capacitor coupled to the second DAC and the second buffer, the capacitance value of the second variable capacitor corresponding to the second control voltage; wherein by controlling at least one of the first and the second digital values, the phase difference between the first input signal and the second input signal is adjusted, and the first input signal and the second input signal are differential signals.