Experimental Study of Noise in a Frequency Synthesizer

This paper presents new results in the noise measurements of frequency synthesizers. Noise phenomena at the output of a synthesizer are very complex. Every component in the synthesizer contributes to the total output measured noise curve. Usually, it is not possible to separate the noise sources by just measuring the noise curve at the output of a frequency synthesizer. In this paper a technique is presented that can be used to investigate the noise contribution of different devices within the synthesizer. For this work, a synthesizer circuit is built and optimized to have a low noise floor. Then stronger noise is added at different points in the synthesizer in a way that it would represent noise of a certain device in the system, and that its provenance might be identified clearly. In advancement to the previous presentations, a very complex combination of noise sources is taken into consideration.