AUTOMATED INTERFEROMETRIC NOISE MEASUREMENT

摘要

In one embodiment, an automated interferometric noise measurement system includes: a signal source adapted to provide a carrier signal; a delay line adapted to delay a first version of the carrier signal to provide a delayed signal to a device-under-test (DUT); a variable attenuator adapted to attenuate a second version of the carrier signal to provide an attenuated signal; a first variable phase-shifter adapted to phase-shift the attenuated signal to provide a first phase-shifted signal; a hybrid coupler adapted to receive an output signal from the DUT and the first phase- shifted signal to provide a carrier-suppressed signal and a carrier-enhanced signal; a low-noise amplifier adapted to amplify the carrier-suppressed signal to provide an amplified signal; a second variable phase-shifter adapted to phase-shift a version of the carrier-enhanced signal to provide a second phase-shifted signal; a first mixer adapted to mix a first version of the amplified signal and the second phase-shifted signal to provide a first noise signal; and a controller adapted to control the variable attenuator, the first and second phase-shifters, and the low-noise amplifier responsive to a zero-crossing value in the first noise signal.