Patent ID: 8093907

Claim:
A test apparatus operative to transmit a differential signal bidirectionally to and from a device under test via a differential transmission line pair and to test the device under test, comprising: a main driver amplifier operative to generate a first differential signal based on pattern data to be transmitted to the device under test; a first replica driver amplifier operative to generate a second differential signal based on the pattern data; a second replica driver amplifier operative to generate a third differential signal based on the pattern data; a first comparator; a second comparator; a first resistor provided between one output terminal of the main driver amplifier and a first terminal to which one of the differential transmission line pair is connected; a second resistor provided between the other output terminal of the main driver amplifier and a second terminal to which the other of the differential transmission line pair is connected; a third resistor provided between the first terminal and one input terminal of the first comparator; a fourth resistor provided between the second terminal and the other input terminal of the first comparator; a fifth resistor provided between the second terminal and one input terminal of the second comparator; a sixth resistor provided between the first terminal and the other input terminal of the second comparator; a seventh resistor provided between one output terminal of the first replica driver amplifier and the other input terminal of the first comparator; an eighth resistor provided between the other output terminal of the first replica driver amplifier and the other input terminal of the second comparator; a ninth resistor provided between one output terminal of the second replica driver amplifier and one input terminal of the second comparator; and a tenth resistor provided between the other output terminal of the second replica driver amplifier and one input terminal of the first comparator.