Noise minimization techniques for voltage controlled crystal oscillator (VCXO) circuits

Rohde, Ulrich L.; Poddar, Ajay K.

doi:10.1109/rws.2009.4957333

Cited by 8 publications

(2 citation statements)

References 8 publications

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“…In the thermally limited quartz oscillator, a quartz resonator is present between the core and the buffer. Such filter can be the main resonator if the carrier is extracted from the resonator's ground pin [29], [30, figure 4-58 to 4-61], or a second quartz resonator (figure 9(B)). Out of the resonator bandwidth ν 0 (1 ± 1/2Q), the quartz is a high impedance circuit, thus the noise of the sustaining amplifier is not transmitted to the buffer.…”

Section: Inside the Oscillatormentioning

confidence: 99%

Artifacts and errors in cross-spectrum phase noise measurements

Gruson

Rus²,

Rohde

et al. 2020

Metrologia

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This article is intended to give a warning about: (i) the internal processing inside the phase-noise analyzers, (ii) the oscillators whose white phase noise floor seems too low, chiefly the 100-MHz OCXOs, and (iii) the need to introduce in the domain of phase-noise measurements the basic concepts of uncertainty found in the International Vocabulary of Metrology (VIM).The measurement of low-noise quartz oscillators, or of other lownoise oscillators exhibiting a noise floor of the order of −180 dBc/Hz or less, relies on the cross-spectrum method. The measurement may take long time, from hours to 1-2 days, for the number of averaged cross spectra to be sufficient to reject the background of the noise analyzer. That said, something anomalous is often seen in a region approximately one decade wide, located where higher-slope noise joins the white floor or the 1/f noise. The plot may be quite thick and irregular, and a dip may appear, where the phase noise looks lower than the white noise floor. Such anomalies reveal something worse. The white region of the PM noise spectrum may be affected by gross errors and, in the not-so-rare worst case, is a total nonsense. We address the problem trough a simple experiment, where we insert a dissipative attenuator between the oscillator and the PN analyzer. Surprisingly, in some cases the attenuation results in a lower noise floor. Such erratic behavior is reproducible, having been observed separately in three labs with instruments from the two major brands. We provide the experimental evidence, the full theory, and suggestions to mitigate the problem.

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Section: Inside the Oscillatormentioning

confidence: 99%

Artifacts and errors in cross-spectrum phase noise measurements

Gruson

Rus²,

Rohde

et al. 2020

Metrologia

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“…However, it is challenging to design high performance VCXOs in CMOS process, since MOS transistors have bad noise performance compared with bipolar transistors, and high quality varactors are hardly implemented in CMOS process. Therefore, to alleviate these issues, most published papers use BiCMOS process or other special processes to design VCXOs OE4; 5 . In this paper, we proposed a low-cost frequency doubling VCXO in standard CMOS process.…”

Section: Introductionmentioning

confidence: 99%

A fully integrated CMOS VCXO-IC with low phase noise, wide tuning range and high tuning linearity

Yang

Zeng

2015

J. Semicond.

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This paper describes a low phase noise, wide tuning range and high tuning linearity CMOS voltage controlled crystal oscillator IC (VCXO-IC) with LVCMOS and LVPECL output. A differential coupled frequency doubling Colpitts oscillator is adopted to obtain low noise 2 frequency output. Wide tuning range and high linearity are simultaneously achieved by using MOS varactor arrays. The measurement results show that the designed VCXO-IC achieves 134 dBc/Hz phase noise at 1 kHz offset frequency and ˙135 ppm output frequency tuning range within 3% linearity by using 40 MHz fundamental AT-cut crystal. The VCXO-IC is fabricated in the chartered 0.35 m standard CMOS process and occupies a total silicon area of 2.4 mm 2 .

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Crystal Oscillators

Poddar

Rohde

2012

Wiley Encyclopedia of Electrical and Electronics Engineering

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As a result of high Q ‐factor and temperature‐stable properties, quartz crystal oscillators have been important clock sources in consumer, commercial, industrial, and military products for many years. This contribution is devoted to crystal oscillator theory for reference frequency signal source applications. This article discusses the behavior of crystal over temperature and aging, selection of modes, start‐up dynamics, and noise‐minimization techniques for the applications in current and later generation communication systems. Several practical examples are demonstrated and validated with simulated and measured results for the benefit of readers.

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Noise minimization techniques for voltage controlled crystal oscillator (VCXO) circuits

Cited by 8 publications

References 8 publications

Artifacts and errors in cross-spectrum phase noise measurements

Artifacts and errors in cross-spectrum phase noise measurements

A fully integrated CMOS VCXO-IC with low phase noise, wide tuning range and high tuning linearity

Crystal Oscillators

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