arXiv subjects

Enrico Rubiola

Publications and source records attributed to Enrico Rubiola.

At least 37 records · Page 2Linked to original sources

arXiv2019

Noise Analysis of Open-Loop and Closed-Loop SAW Magnetic Field Sensor Systems

Transmission surface acoustic wave (SAW) sensors are widely used in various fields of application. In order to maximize the limit of detection (LOD) of such sensor systems, it is of high importance to understand and to be able to quantify the relevant noise sources. In this paper, low noise readout systems for the application with a SAW delay line magnetic field sensor in an open-loop and closed-loop configuration are presented and analyzed with regard to their phase noise contribution. By applying oscillator phase noise theory to closed-loop sensor systems, it is shown that the phase noise of the SAW delay line oscillator can be predicted accurately. This allows the derivation of expressions for the limits of detection for both readout structures. Based on these equations, the equivalence between the LOD of open-loop and closed-loop SAW delay line readout can be shown analytically, assuming that the sensor contributes the dominant phase noise. This equality is verified by measurements. These results are applicable to all kinds of phase sensitive delay line sensors.

physics.ins-det↗

arXiv2018

Equivalence of Open-Loop and Closed-Loop Operation of SAW Resonators and Delay Lines

Surface acoustic wave (SAW) sensors in the form of two-port resonators or delay lines are widely used in various fields of application. Readout of such sensors is achieved by electronic systems operating either in an open-loop or in a closed-loop configuration. The mode of operation of the sensor system is usually chosen based on requirements like e.g. bandwidth, dynamic range, linearity, costs, and immunity against environmental influences. Because the limit of detection (LOD) at the output of a sensor system is often one of the most important figures of merit, both readout structures, i.e. open-loop and closed-loop systems, are analyzed in terms of the minimum achievable LOD. Based on a comprehensive phase noise analysis of these structures for both, resonant sensors and delay line sensors, expressions for the various limits of detection are derived. Under generally valid conditions equivalence of open-loop and closed-loop operation is shown for both types of sensors. These results are not only valid for SAW devices but are also applicable to all kinds of phase sensitive sensors.

physics.ins-det↗

arXiv2017

Residual Phase Noise Measurement of Optical Second Harmonic Generation in PPLN Waveguides

We report on the characterization, including residual phase noise and fractional frequency instability, of fiber-coupled PPLN non-linear crystals. These components are devoted to frequency doubling 871 nm light from an extended-cavity diode laser to produce a 435.5 nm beam, corresponding to the ytterbium ion electric quadrupole clock transition. We measure doubling efficiencies of up to 117.5 %/W. Using a Mach-Zehnder interferometer and an original noise rejection technique, the residual phase noise of the doublers is estimated to be lower than ${\rm -35\, dBrad^2/Hz}$ at 1 Hz, making these modules compatible with up-to-date optical clocks and ultra-stable cavities. The influence of external parameters such as pump laser frequency and intensity is investigated, showing that they do not limit the stability of the frequency-doubled signal. Our results demonstrate that such compact, fiber-coupled modules are suitable for use in ultra-low phase noise metrological experiments, including transportable optical atomic clocks.

physics.ins-det↗

arXiv2016

Phase Noise and Jitter in Digital Electronics

This article explains phase noise, jitter, and some slower phenomena in digital integrated circuits, focusing on high-demanding, noise-critical applications. We introduce the concept of phase type and time type phase noise. The rules for scaling the noise with frequency are chiefly determined by the spectral properties of these two basic types, by the aliasing phenomenon, and by the input and output circuits. Then, we discuss the parameter extraction from experimental data and we report on the measured phase noise in some selected devices of different node size and complexity. We observed flicker noise between -80 and -130 dBrad^2/Hz at 1 Hz offset, and white noise down to -165 dBrad^2/Hz in some fortunate cases and using the appropriate tricks. It turns out that flicker noise is proportional to the reciprocal of the volume of the transistor. This unpleasant conclusion is supported by a gedanken experiment. Further experiments provide understanding on: (i) the interplay between noise sources in the internal PLL, often present in FPGAs; (ii) the chattering phenomenon, which consists in multiple bouncing at transitions; and (iii) thermal time constants, and their effect on phase wander and on the Allan variance.

physics.ins-det↗

arXiv2016

Cross-Spectrum PM Noise Measurements, Thermal Energy and Metamaterial Filters

Virtually all commercial instruments for the measurement of the oscillator PM noise make use of the Cross Spectrum method (arXiv:1004.5539 [physics.ins-det], 2010). High sensitivity is achieved by correlation and averaging on two equal channels which measure the same input, and reject the background of the instrument. We show that a systematic error is always present if the thermal energy of the input power splitter is not accounted for. Such error can result in noise under estimation up to a few dB in the lowest-noise quartz oscillators, and in a complete nonsense in the case of cryogenic oscillators. As another alarming fact, the presence of metamaterial components in the oscillator results in unpredictable behavior and large errors, even in well controlled experimental conditions. We observed a spread of 40 dB in the phase noise spectra of an oscillator, just replacing the output filter.

physics.ins-det↗

arXiv2016

Least square estimation of phase, frequency and PDEV

The Omega-preprocessing was introduced to improve phase noise rejection by using a least square algorithm. The associated variance is the PVAR which is more efficient than MVAR to separate the different noise types. However, unlike AVAR and MVAR, the decimation of PVAR estimates for multi-tau analysis is not possible if each counter measurement is a single scalar. This paper gives a decimation rule based on two scalars, the processing blocks, for each measurement. For the Omega-preprocessing, this implies the definition of an output standard as well as hardware requirements for performing high-speed computations of the blocks.

physics.data-an↗

arXiv2016

Characterization of Zero-Bias Microwave Diode Power Detectors at Cryogenic Temperature

We present the characterization of commercial tunnel diode low-level microwave power detectors at room and cryogenic temperatures. The sensitivity as well as the output voltage noise of the tunnel diodes are measured as functions of the applied microwave power, the signal frequency being 10 GHz. We highlight strong variations of the diode characteristics when the applied microwave power is higher than few microwatt. For a diode operating at ${4}$ K, the differential gain increases from ${1,000}$ V/W to about ${4,500}$ V/W when the power passes from ${-30}$ dBm to ${-20}$ dBm. The diode present a white noise floor equivalent to a NEP of ${0.8}$ pW/ ${\sqrt{\mathrm{Hz}}}$ and ${8}$ pW/${ \sqrt{\mathrm{Hz}}}$ at 4 K and 300 K respectively. Its flicker noise is equivalent to a relative amplitude noise power spectral density ${S_α(1~\mathrm{Hz})=-120}$~dB/Hz at ${4}$ K. Flicker noise is 10 dB higher at room temperature.

physics.ins-det↗

arXiv2015

Characterization of the individual short-term frequency stability of Cryogenic Sapphire Oscillators at the 1e-16 level

We present the characterisation of three Cryogenic Sapphire Oscillators using the three-corner-hat method. Easily implemented with commercial components and instruments, this method reveals itself very useful to analyse the frequency stability limitations of these state-of-the-art ultra-stable oscillators. The best unit presents a fractional frequency stability better than 5e-16 at 1 s and below 2e-16 for integration times less than 5,000s.

physics.ins-det↗

arXiv2014

Influence of the ESR saturation on the power sensitivity of cryogenic sapphire resonators

Here, we study the paramagnetic ions behavior in presence of a strong microwave electromagnetic field sustained inside a cryogenic sapphire whispering gallery mode resonator. The high frequency measurement resolution that can be now achieved by comparing two CSOs permit for the first time to observe clearly the non-linearity of the resonator power sensitivity. These observations that in turn allow us to optimize the CSO operation, are well explained by the Electron Spin Resonance (ESR) saturation of the paramagnetic impurities contained in the sapphire crystal.

physics.ins-det↗

arXiv2012

Phase Noise in RF and Microwave Amplifiers

Understanding the amplifier phase noise is a critical issue in numerous fields of engineering and physics, like oscillators, frequency synthesis, telecommunications, radars, spectroscopy, in the emerging domain of microwave photonics, and in more exotic domains like radio astronomy, particle accelerators, etc. This article analyzes the two main types of phase noise in amplifiers, white and flicker. White phase noise results from adding white noise to the RF spectrum around the carrier. For a given amount of RF noise added, noise is proportional to the inverse of the carrier power. By contrast, the 1/f coefficient is a constant parameter of the amplifier, in a wide range of carrier power. This fact has amazing consequences on different amplifier topologies. Connecting m equal amplifiers in parallel, flicker is 1/m times that of one device. Cascading m equal amplifiers, flicker is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in dB) due to positive feedback (regeneration), which for integer m is similar to the case of m amplifiers, we find that flicker is m^2 times that of the amplifier alone. Starting from the fact that near-dc flicker exists in all electronic devices, although generally not accessible from outside, the simplest model for the 1/f phase noise is that the near-dc 1/f noise phase-modulates the carrier through some parametric effect in the semiconductor. This model predicts the behavior of the (simple) amplifier and of the different amplifier topologies. Numerous measurements on amplifiers from different technologies and frequencies (HF to microwaves), also including some obsolete amplifiers, validate the theory.

physics.ins-det↗

arXiv2010

Unprecedented High Long Term Frequency Stability with a Macroscopic Resonator Oscillator

This article reports on the long-term frequency stabilty characterisation of a new type of cryogenic sapphire oscillator using an autonomous pulse-tube cryocooler as its cold source. This new design enables a relative frequency stability of better than 4.5e-15 over one day of integration. This represents to our knowledge the best long-term frequency stability ever obtained with a signal source based on a macroscopic resonator.

physics.ins-det↗

arXiv2010

A generalization of the Leeson effect

The oscillator, inherently, turns the phase noise of its internal components into frequency noise, which results into a multiplication by 1/f^2 in the phase-noise power spectral density. This phenomenon is known as the Leeson effect. This report extends the Leeson effect to the analysis of amplitude noise. This is done by analyzing the slow-varying complex envelope, after freezing the carrier. In the case of amplitude noise, the classical analysis based on the frequency-domain transfer function is possible only after solving and linearizing the complete differential equation that describes the oscillator. The theory predicts that AM noise gives an additional contribution to phase noise. Beside the detailed description of the traditional oscillator, based on the resonator governed by a second-order differential equation (microwave cavity, quartz oscillators etc.), this report is a theoretical framework for the analysis of other oscillators, like for example the masers, lasers, and opto-electronic oscillators. This manuscript is intended as a standalone report, and also as complement to the book E. Rubiola, Phase Noise and Frequency Stability in Oscillators, Cambridge University Press, 2008. ISBN 978-0-521-88677-2 (hardback), 978-0-521-15328-7 (paperback).

physics.ins-det↗

arXiv2010

The cross-spectrum experimental method

The noise of a device under test (DUT) is measured simultaneously with two instruments, each of which contributes its own background. The average cross power spectral density converges to the DUT power spectral density. This method enables the extraction of the DUT noise spectrum, even if it is significantly lower than the background. After a snapshot on practical experiments, we go through the statistical theory and the choice of the estimator. A few experimental techniques are described, with reference to phase noise and amplitude noise in RF/microwave systems and in photonic systems. The set of applications of this method is wide. The final section gives a short panorama on radioastronomy, radiometry, quantum optics, thermometry (fundamental and applied), semiconductor technology, metallurgy, etc. This report is intended as a tutorial, as opposed to a report on advanced research, yet addressed to a broad readership: technicians, practitioners, Ph.D. students, academics, and full-time scientists.

physics.ins-det↗

arXiv2009

About Quartz Crystal Resonator Noise: Recent Study

The first step, before investigating physical origins of noise in resonators, is to investigate correlations between external measurement parameters and the resonator noise. Tests and measurements are mainly performed on an advanced phase noise measurement system, recently set up. The resonator noise is examined as a function of the sensitivity to the drive level, the temperature operating point and the tuning capacitor.

physics.ins-det↗

arXiv2009

Primary calibration of AM and PM noise measurements

This report describes a method for the primary calibration of phase noise and amplitude noise measurement systems. In the field of metrology, the term "primary" refers to a standard whose quantity value and measurement uncertainty are established without relation to another measurement standard for a quantity of the same kind; or to a procedure used to realize the definition of a measurement unit and obtain the quantity value and measurement uncertainty of a primary measurement standard. Accordingly, a phase and a normalized amplitude have to rely on ratio measurements.

physics.ins-det↗

arXiv2008

Phase and frequency noise metrology

As a consequence of a general trend in the physics of oscillators and clocks towards optics, phase and frequency metrology is rapidly moving to optics too. Yet, optics is not replacing the traditional radio-frequency (RF) and microwave domains. Instead, it adds tough challenges. Precision frequency-stability measurements are chiefly based on the measurement of phase noise, which is the main focus of this article. Major progress has been achieved in two main areas. The first is the extreme low-noise measurements, based on the bridge (interferometric) method in real time or with sophisticated correlation and averaging techniques. The second is the emerging field of microwave photonics, which combines optics and RF/microwaves. This includes the femtosecond laser, the two-way fiber links, the noise measurement systems based on the fiber and the photonic oscillator. Besides, the phenomenology of flicker (1/f) noise is better understood, though the ultimate reasons are still elusive.

physics.ins-det↗

arXiv2008

Applications of the optical fiber to the generation and to the measurement of low-phase-noise microwave signals

The optical fiber used as a microwave delay line exhibits high stability and low noise and makes accessible a long delay (>100 microseconds) in a wide bandwidth (about 40 GHz, limited by the optronic components). Hence, it finds applications as the frequency reference in microwave oscillators and as the reference discriminator for the measurement of phase noise. The fiber is suitable to measure the oscillator stability with a sensitivity of parts in 1E-12. Enhanced sensitivity is obtained with two independent delay lines, after correlating and averaging. Short-term stability of parts in 1E-12 is achieved inserting the delay line in an oscillator. The frequency can be set in steps multiple of the inverse delay, which is in the 10-100 kHz region. This article adds to the available references a considerable amount of engineering and practical knowledge, the understanding of 1/f noise, calibration, the analysis of the cross-spectrum technique to reduce the instrument background, the phase-noise model of the oscillator, and the experimental test of the oscillator model.

physics.optics↗

arXiv2008

Determination of phase noise spectra in optoelectronic microwave oscillators: a Langevin approach

We introduce a stochastic model for the determination of phase noise in optoelectronic oscillators. After a short overview of the main results for the phase diffusion approach in autonomous oscillators, an extension is proposed for the case of optoelectronic oscillators where the microwave is a limit-cycle originated from a bifurcation induced by nonlinearity and time-delay. This Langevin approach based on stochastic calculus is also successfully confronted with experimental measurements.

physics.optics↗