Differential comparator with skew compensation function and test apparatus using the same

A differential comparator that receives differential signals outputted from a device to be tested, and compares a differential amplitude of the differential signals with a threshold voltage, the differential comparator comprising:

• a first input terminal to which one of the differential signals is inputted;
• a second input terminal to which the other of the differential signals is inputted;
• a first sample hold circuit that samples the signal inputted to the first input terminal at a designated timing, and holds it thereafter;
• a second sample hold circuit that samples the signal inputted to the second input terminal at a designated timing, and holds it thereafter;
• a comparison unit that compares a signal corresponding to a difference between respective output signals from the first and the second sample hold circuits, with a predetermined threshold value;
• and
• a latch circuit that latches an output from the comparison unit, wherein sampling timings of the first and the second sample hold circuits, and a latch timing of the latch circuit, can be adjustable independently.