Oscillator circuit and test apparatus

A test apparatus that tests an electronic device, the test apparatus comprising:

• a pattern generator that generates a test pattern to test the electronic device;
• an oscillator circuit that generates an oscillation signal having a frequency determined in accordance with a frequency of a test signal to be input into the electronic device;
• a waveform shaper that generates the test signal to be input into the electronic device based on the test pattern generated by the pattern generator and the oscillation signal generated by the oscillator circuit;
• and
• a judging section that judges whether the electronic device is good or bad by comparing an output signal output from the electronic device with an expected value pattern generated by the pattern generator, wherein
• the oscillator circuit includes:
• an oscillator that generates the oscillation signal based on positive feedback of a signal;
• a synchronization signal generating section that generates a compulsory synchronization signal having an edge that (i) crosses a zero cross point at an ideal timing of an edge of the oscillation signal every predetermined number of cycles of the oscillation signal and (ii) has a gradient in the same direction as the edge of the oscillation signal;
• and
• a combining section that injects the compulsory synchronization signal into a positive feedback path of the oscillator.