Patent ID: 7949922
Filing Date: 2011-05-24
Classification: G01R

Abstract:
1. A test apparatus for testing a device under test, comprising: a signal input section that shifts a phase of a test signal in accordance with a designated value of a shift amount supplied thereto, and inputs the phase-shifted test signal to the device under test; a device judging section that evaluates the device under test based on an output signal output from the device under test in response to the input test signal; and a shift amount measuring section that measures a phase shift amount of the test signal output from the signal input section, the shift amount measuring section including: a first loop circuit that generates a synchronization signal which is synchronized with a reference signal; a phase control circuit that inputs, into the first loop circuit, a first control signal which has a value determined in accordance with a difference in phase between the synchronization signal and the test signal, so as to achieve a predetermined difference in phase between the synchronization signal and the test signal; and a measuring circuit that, before and after the test signal is phase-shifted, measures the value of the first control signal when the predetermined difference in phase is achieved between the synchronization signal and the test signal, and detects the phase shift amount of the test signal based on a result of the measurement.