A Digital Method for Phase Noise Measurement

An all-digital method is used to detect sinusoidal phase noise components while reducing the need for computation intensive post-processing. We use the frequency-selective behavior of a narrow bandwidth infinite impulse response (IIR) digital filter to replace the frequency- domain evaluation of an FFT. This form of digital post-processing reduces the calculation overhead of making frequency-domain observations. We provide a model for the inherent nonidealities of the relevant quantization processes which will need to be managed in a practical implementation of this technique for manufacturing test. We also present a method for capturing phase noise amplitude from arbitrary bit stream data. This extension allows the technique to function on any set of binary data that has sufficient edges to provide information on the phase noise under evaluation.