Patent ID: 7791390
Filing Date: 2010-09-07
Classification: H03K,H03L

Abstract:
1. A phase shifter, comprising: an AC component amplifying unit having positive gain slope characteristics and deforming a waveform of an input differential clock signal to output a deformed differential clock signal and amplifying AC components of the input differential clock signal in a frequency range where signal intensity is changed due to a deterioration of duty ratios of the input differential clock signal; a dividing circuit including a T-flipflop having two D latches connected in series and receiving the deformed differential clock signal deformed by the AC component amplifying unit to generate at least two output signals having a phase difference of 90 degrees with a frequency of ½ of the deformed differential clock signal; a detecting unit detecting a phase difference between the two output signals and outputting a control signal corresponding to the detected phase difference; and a variable capacitor connected to an output line of at least one of the two output signals and capable of changing a capacitance in accordance with the control signal.