Bandwidth Extension of Low Noise Fractional-N Synthesizers

Date Added: Aug 2009
Format: PDF

In this paper, the authors examine issues with extending the bandwidth of fractional-N synthesizers. Quantization noise is shown to be the limiting factor in state-of-the-art fractional-N synthesis. A re-framing of the noise model used to analyze synthesizer phase noise leads directly to a methodology to enable high bandwidth synthesis. They present measured results from a synthesizer based on the proposed methodology that demonstrates >25dB broadband phase noise reduction compared to a state-of-the-art synthesizer. Finally, they draw conclusions about the future direction of fractional-N synthesis.