Influence of Initial Condition on Wandering Spur Pattern in a MASH-Based Fractional-<i>N</i> Frequency Synthesizer

Mai, Dawei; Kennedy, Michael Peter

doi:10.1109/tcsii.2020.2985640

Cited by 5 publications

(5 citation statements)

References 6 publications

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“…In these two cases, periodic wandering spur events can be observed. By contrast, wandering spurs that are independent of the nonlinearity, i.e., the spurs are inherent to the synthesizer, are present in Case III [14]. In Case III, the divider controller noise is directly related to the e 3 [n] signal that contains the wandering spur pattern.…”

Section: B Categorization Of Wandering Spursmentioning

confidence: 98%

“…The wandering spur generating mechanisms in a MASH 1-1-1 DDSM-based fractional-N frequency synthesizer have been elaborated in [6] and [14]. Wanderings spurs have been classified into three cases based on the input to the MASH 1-1-1 DDSM divider controller [6], [14]. Denote the constant input to the MASH 1-1-1 as x[n] = X, and express X in the form…”

Section: B Categorization Of Wandering Spursmentioning

confidence: 99%

“…The root cause of wandering spurs in a MASH 1-1-1 DDSM-based fractional-N frequency synthesizer is the double accumulation of a constant within the MASH divider controller. The analysis reveals that the quantization error of the second stage either contains the underlying pattern itself or causes the underlying pattern to arise in the third-stage quantization error [6], [14].…”

Section: A Prior Art: High-amplitude Dither Solutionmentioning

confidence: 99%

“…According to the analysis in [6], the presence of nonlinearity in a synthesizer gives rise to the wandering spurs in Case I and Case II. In Case III, the MASH 1-1-1-based synthesizer would exhibit wandering spurs even if there were no nonlinearity [14]. Therefore, only the results for Case I and Case III are presented due to the qualitatively similar generating mechanism between Case I and Case II.…”

Section: B Spectrograms Of Output Phase Noisementioning

confidence: 99%

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Wandering Spur Suppression in a 4.9-GHz Fractional-N Frequency Synthesizer

Mai

Donnelly²,

Kennedy

et al. 2022

IEEE J. Solid-State Circuits

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Fractional-N frequency synthesizers that use a digital -modulator (DDSM) to control the feedback divider can exhibit spurious tones that move about in the frequency domain; these are known colloquially as "walking" or wandering spurs. Building upon a theoretical explanation of the origin of wandering spurs, this article presents two methods to suppress them. It describes a 4.9-GHz 180-nm SiGe BiCMOS charge-pump phase-locked loop (CP-PLL) fractional-N frequency synthesizer platform with a divider controller that can function as: 1) a standard MASH 1-1-1; 2) a MASH 1-1-1 with high-amplitude dither; and 3) a MASH 1-1-1 with a modified third stage. Measurements confirm the effectiveness of the wandering spur suppression strategies.

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Section: B Categorization Of Wandering Spursmentioning

confidence: 98%

Section: B Categorization Of Wandering Spursmentioning

confidence: 99%

Section: A Prior Art: High-amplitude Dither Solutionmentioning

confidence: 99%

Section: B Spectrograms Of Output Phase Noisementioning

confidence: 99%

See 2 more Smart Citations

Wandering Spur Suppression in a 4.9-GHz Fractional-N Frequency Synthesizer

Mai

Donnelly²,

Kennedy

et al. 2022

IEEE J. Solid-State Circuits

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“…The first line of the table corresponds to the case when the fraction α is close to zero. In the special case when X = 0, the wandering spur pattern also depends on the initial condition of the divider controller [45]. [44] Input Condition Wander rate Period…”

Section: Wandering Spursmentioning

confidence: 99%

Nonlinearity-Induced Spurs in Fractional-NFrequency Synthesizers

Kennedy

Mazzaro

Mai

2022

IEEE Trans. Circuits Syst. II

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Fractional-N frequency synthesizers are characterized by unwanted periodic components in their frequency spectra called spurs. In communications applications, spurs reduce the signal to noise ratio of the system; in clocking they add jitter; in radar and imaging, they can present ghost targets. Some spurs are due to parasitic electromagnetic coupling between components and can be mitigated by careful circuit layout. Others are inherent in the mathematics that describe the system and are best tackled using mathematical approaches. This paper considers spurs that are introduced directly by the divider controller and those that result from distortion of the control signal by nonlinearity in the synthesizer. It summarizes the state of the art in terms of divider controllers that are themselves spurfree and divider controllers that do not produce spurs when used in synthesizers with memoryless polynomial nonlinearities.

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