Merits of PM noise measurement over noise figure: a study at microwave frequencies
17 Nov 2006-IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (IEEE)-Vol. 53, Iss: 10, pp 1889-1894
TL;DR: This paper primarily addresses the usefulness of phase-modulation noise measurements versus noise figure (NF) measurements in characterizing the merit of an amplifier, and concludes that, although NF is sometimes used as a selection criteria for an amplifier for low-level signal, NF yields no information about potentially important close-to-carrier 1/f noise of an amplifier nor broadband noise in the presence of a high- level signal.
Abstract: This paper primarily addresses the usefulness of phase-modulation (PM) noise measurements versus noise figure (NF) measurements in characterizing the merit of an amplifier. The residual broadband (white PM) noise is used as the basis for estimating the NF of an amplifier. We have observed experimentally that many amplifiers show an increase in the broadband noise of 1 to 5 dB as the signal level through the amplifier increases. This effect is linked to input power through the amplifier's nonlinear intermodulation distortion. Consequently, this effect is reduced as linearity is increased. We further conclude that, although NF is sometimes used as a selection criteria for an amplifier for low-level signal, NF yields no information about potentially important close-to-carrier 1/f noise of an amplifier nor broadband noise in the presence of a high-level signal, but a PM noise measurements does. We also have verified experimentally that the single-sideband PM noise floor of an amplifier due to thermal noise is -177 dBc/Hz, relative to a carrier input power of 0 dBm
Citations
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TL;DR: In this article, a photodetected pulse train timing noise floor at an unprecedented 25 zs Hz−1/2 was reported, by exploiting correlations in the shot-noise spectrum of optical pulse trains.
Abstract: Shot noise originates from the discrete nature of optical field detection. By exploiting correlations in the shot-noise spectrum of optical pulse trains, scientists improve shot-noise-limited optical pulse timing measurements by several orders of magnitude. A photodetected pulse train timing noise floor at an unprecedented 25 zs Hz−1/2 is reported.
114 citations
TL;DR: This work demonstrates an approach based on a fs Er-fiber laser that avoids the complexity of self-referenced stabilization of the offset frequency and measures a residual phase noise on a 1.5 GHz carrier of -120 dBc/Hz at 1 Hz offset.
Abstract: Low phase-noise microwave generation has previously been demonstrated using self-referenced frequency combs to divide down a low noise optical reference. We demonstrate an approach based on a fs Er-fiber laser that avoids the complexity of self-referenced stabilization of the offset frequency. Instead, the repetition rate of the femtosecond Er-fiber laser is phase locked to two cavity-stabilized cw fiber lasers that span 3.74 THz by use of an intracavity electro-optic modulator with over 2 MHz feedback bandwidth. The fs fiber laser effectively divides the 3.74 THz difference signal to produce microwave signals at harmonics of the repetition rate. Through comparison of two identical dividers, we measure a residual phase noise on a 1.5 GHz carrier of -120 dBc/Hz at 1 Hz offset.
64 citations
TL;DR: In this article, the authors demonstrate a 10-15dB reduction in the 10 GHz phase noise floor by multiplication of the pulse repetition rate using Fabry-Perot cavity filtering and a cascaded unbalanced Mach-Zehnder (MZ) fiber-based interferometer.
Abstract: The generation of microwaves from optical signals suffers from thermal and shot noise inherent in the photodetection process. This problem is more acute at lower pulse repetition rates where photodiode saturation limits the achievable signal-to-noise ratio. In this paper, we demonstrate a 10-15-dB reduction in the 10-GHz phase noise floor by multiplication of the pulse repetition rate. Starting with a 250-MHz fundamentally mode-locked erbium (Er):fiber laser, we compare the following two different approaches to repetition rate multiplication: 1) Fabry-Perot cavity filtering and 2) a cascaded, unbalanced Mach-Zehnder (MZ) fiber-based interferometer. These techniques reduce the phase noise floor on the 10-GHz photodetected harmonic to -158 and -162 dBc/Hz, respectively, for Fourier frequencies higher than 100 kHz.
62 citations
Cites background from "Merits of PM noise measurement over..."
...This accounts for a reduction by another factor of two, such that the single-sideband phase noise induced by the thermal noise will be [ 25 ]...
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TL;DR: In this paper, the authors demonstrate a 10-15 dB reduction in the 10 GHz phase noise floor by multiplication of the pulse repetition rate, which is more acute at lower pulse repetition rates where photodiode saturation limits the achievable signal-to-noise ratio.
Abstract: The generation of microwaves from optical signals suffers from thermal and shot noise inherent in the photodetection process. This problem is more acute at lower pulse repetition rates where photodiode saturation limits the achievable signal-to-noise ratio. In this paper, we demonstrate a 10-15 dB reduction in the 10 GHz phase noise floor by multiplication of the pulse repetition rate. Starting with a 250 MHz fundamentally mode-locked erbium(Er):fiber laser, we compare two different approaches to repetition rate multiplication: Fabry-Perot cavity filtering and a cascaded, unbalanced Mach-Zehnder fiber-based interferometer. These techniques reduce the phase noise floor on the 10 GHz photodetected harmonic to -158 dBc/Hz and -162 dBc/Hz, respectively, for Fourier frequencies higher than 100 kHz.
54 citations
References
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01 Jan 1984
TL;DR: In this article, a thorough treatment of phase noise, its relationship to thermal noise and associated subjects such as frequency stability is provided, including the design of low-phase noise signal sources, including oscillators and synthesisers.
Abstract: This book contains a thorough treatment of phase noise, its relationship to thermal noise and associated subjects such as frequency stability. The design of low phase noise signal sources, including oscillators and synthesisers, is explained and in many cases the measured phase noise characteristics are compared with the theoretical predictions. Full theoretical treatments are combined with physical explanations, helpful comments, examples of manufactured equipment and practical tips. Overall system performance degradations due to unwanted phase noise are fully analysed for radar systems and for both analogue and digital communications systems. Specifications for the acceptable phase noise performance of signal sources to be used in such systems are derived after allowing for both technical and economic optimisation. The mature engineer whose mathematics may be somewhat rusty will find that every effort has been made to use the lowest level of mathematical sophistication that is compatible with a full analysis and every line of each mathematical argument has been set out so that the book may be read and understood even in an armchair. Due to a novel approach to the analytical treatment of narrow band noise, the book is simple to understand while simultaneously carrying the analysis further in several areas than any existing publication.
320 citations
27 May 1987
TL;DR: A review of the sources and characteristics of frequency fluctuations in stable oscillators using quartz acoustic resonators (BAW and SAW) or dielectric resonators as the high Q frequency stabilizing element is presented in this article.
Abstract: The frequency stability of an oscillator is a very important characteristic for many applications. Yet the causes and sources of some basic types of noise are poorly understood, particularly for close-to-carrier noise. A review is presented in this paper of the present state of knowledge about the sources and characteristics of frequency fluctuations in stable oscillators using quartz acoustic resonators (BAW and SAW) or dielectric resonators as the high Q frequency stabilizing element. A brief discussion of the various parameters used to quantify random frequency fluctuations is presented along with the relative merits of open- and closed-loop phase noise measurements. Phase noise in stable oscillators usually arises from additive voltage fluctuations and direct parameter modulation processes. Additive
157 citations
"Merits of PM noise measurement over..." refers methods in this paper
...that a PM noise floor of an amplifier due to thermal noise is −177 dBc/Hz, rather than −174 dBc/Hz (referenced to 0 dBm) as reported in previous literature [9], [10]....
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27 May 1992
TL;DR: In this paper, the phase noise floor of a typical two-channel phase noise measurement system is set by the phase detector and amplifiers that follow the detector, and the time required to reach a given percentage of precision in the measurement is lengthened due to the need to average away the uncorrelated noise.
Abstract: The noise floor of a typical two channel phase noise measurement system is set by the phase detector and amplifiers that follow the detector. If the phase noise of two oscillators is measured using two of these test systems, the output noise of the equipment is uncorrelated except for the component that is due to the phase noise between the oscillators. Examination of a system which uses matched power splitters, two phase detectors, and post amplifiers reveals that an exceptionally low noise floor is achievable. The time required to reach a given percentage of precision in the measurement at these low noise floors is lengthened due to the need to average away the uncorrelated noise. The details of the setup, including calibration procedures and confidence intervals for the measurement, are discussed. >
145 citations
88 citations
01 Jun 1988
TL;DR: In this article, a survey of traditional precision techniques for measuring phase noise is provided as a basis for comparing relative performance and limitations, and several calibration techniques are developed which, when combined with two previous oscillator techniques, permit one to calibrate all factors affecting the measurements of phase noise of oscillator pairs to an accuracy which typically exceeds 1 dB and in favorable cases can approach 0.4 dB.
Abstract: Recent progress in extending high-accuracy measurements of phase noise in oscillators and other devices are described for carrier frequencies from the RF to the millimeter region and Fourier frequencies up to 10% of the carrier (or a maximum of about 1 GHz). A brief survey of traditional precision techniques for measuring phase noise is included as a basis for comparing relative performance and limitations. Several calibration techniques are developed which, when combined with two previous oscillator techniques, permit one to calibrate all factors affecting the measurements of phase noise of oscillator pairs to an accuracy which typically exceeds 1 dB and in favorable cases can approach 0.4 dB. >
87 citations
"Merits of PM noise measurement over..." refers background in this paper
...The time average of the incoherent noise [6], [7] approaches zero as N−1/2, where N is the number of averages....
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