APPARATUS ENABLING USE OF A REFERENCE DIODE TO COMPARE AGAINST A DEVICE UNDER TEST IN RELATIVE AMPLITUDE AND PHASE MEASUREMENTS

摘要

Embodiments of the invention include methods and devices for determining a phase angle offset between a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source and an optical phase adjustor, which may be embodied by a loop stretcher structured to controllably stretch a length of fiber optic cable, driven by a phase adjust driver. In other embodiments the phase angle offset information is conveyed to an oscilloscope for internal compensation.