Patent ID: 8269569

Claim:
A test apparatus configured to supply data subjected to digital multi-value modulation to a device under test configured to transmit and receive multiple channels of data subjected to digital multi-value modulation, wherein the test apparatus comprises digital modulators in increments of channels, and wherein the digital modulator comprises: a first baseband signal generator configured to perform retiming of first data input as a modulation signal for an in-phase component using a first timing signal the timing of which can be adjusted, so as to generate a first baseband signal; a second baseband signal generator configured to perform retiming of second data input as a modulation signal for a quadrature component using a second timing signal the timing of which can be adjusted, so as to generate a second baseband signal; a first multi-level driver configured to generate a first multi-value digital signal having a level that corresponds to the value of the baseband signal output from the first baseband signal generator; a second multi-level driver configured to generate a second multi-value digital signal having a level that corresponds to the value of the baseband signal output from the second baseband signal generator; a first multiplier configured to amplitude-modulate an in-phase carrier signal with the first multi-value digital signal; a second multiplier configured to amplitude-modulate a quadrature carrier signal with the second multi-value digital signal; and an adder configured to sum the output signals of the first and second multipliers.