A novel approach to the simultaneous measurement of phase and amplitude noise of oscillators

An approach for the simultaneous measurement of amplitude and phase noise in oscillators is presented. A description of the measurement system and the associated processing techniques is presented. The measurement system includes a conventional complex (I & Q) demodulator, a high speed sampler and a digital computer. The techniques are named time-domain phase unwrapping and real amplitude de-enveloping. They permit the reconstruction of the demodulated I and Q signals as a vector rotating at a convenient beat frequency randomized, in phase and magnitude, by noise. The problems encountered in conventional AM and PM detection can be overcome using the approaches described. As a result, direct and true amplitude and phase noise can be measured and characterized