Applications of interferometric signal processing to phase-noise reduction in microwave oscillators

Ivanov, Eugene; Tobar, Michael E.; Woode, R.A.

doi:10.1109/22.721162

Cited by 82 publications

(40 citation statements)

References 16 publications

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“…A fully polar control based on a phase and amplitude detector and on a phase and amplitude modulator, similar to that used to extend the dynamic range of spectrum analyzers by removing a 'dazzling' carrier [Hor69], suffers from the basic difficulty that the phase becomes undefined as the residual signal approaches zero. The mixed polar-Cartesian control, based on a phase and amplitude modulator as the actuator and on a mixer pair as the detector, is simpler than our scheme; it has been successfully used to stabilize a microwave oscillator [ITW98]. Yet, the mixed control is incompatible with the nested interferometer scheme because the residual carrier, made small by the inner interferometer, spans over a wide range of relative amplitude, for the loop gain of the phase channel is unpredictable and can also change sign.…”

Section: Automatic Carrier Suppressionmentioning

confidence: 99%

“…The instrument of the interferometric type, derived from early works [San68,Lab82], show the highest sensitivity; new applications for them have been reported [ITW98]. Two recent papers provide insight and new design rules for general and real-time measurements [RGG99] and give the full explanation of the white noise limit in correlation-and-averaging measurements [RG00a].…”

Section: Introductionmentioning

confidence: 99%

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Advanced interferometric phase and amplitude noise measurements

Rubiola

Giordano

2002

Review of Scientific Instruments

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The measurement of the close-to-the-carrier noise of two-port radiofrequency and microwave devices is a relevant issue in time and frequency metrology and in some fields of electronics, physics and optics. While phase noise is the main concern, amplitude noise is often of interest. Presently the highest sensitivity is achieved with the interferometric method, that consists of the amplification and synchronous detection of the noise sidebands after suppressing the carrier by vector subtraction of an equal signal. A substantial progress in understanding the flicker noise mechanism of the interferometer results in new schemes that improve by 20-30 dB the sensitivity at low Fourier frequencies. These schemes, based on two or three nested interferometers and vector detection of noise, also feature closed-loop carrier suppression control, simplified calibration, and intrinsically high immunity to mechanical vibrations.The paper provides the complete theory and detailed design criteria, and reports on the implementation of a prototype working at the carrier frequency of 100 MHz. In real-time measurements, a background noise of −175 to −180 dB dBrad 2 /Hz has been obtained at f = 1 Hz off the carrier; the white noise floor is limited by the thermal energy kBT0 referred to the carrier power P0 and by the noise figure of an amplifier. Exploiting correlation and averaging in similar conditions, the sensitivity exceeds −185 dBrad 2 /Hz at f = 1 Hz; the white noise floor is limited by thermal uniformity rather than by the absolute temperature. A residual noise of −203 dBrad 2 /Hz at f = 250 Hz off the carrier has been obtained, while the ultimate noise floor is still limited by the averaging capability of the correlator. This is equivalent to a S/N ratio of 2×10 20 with a frequency spacing of 2.5×10 −6 . All these results have been obtained in a relatively unclean electromagnetic environment, and without using a shielded chamber. Implememtation and experiments at that sensitivity level require skill and tricks, for which a great effort is spent in the paper. * Université Henri Poincaré, Nancy, France, www.rubiola.org, e-mail enrico@rubiola.org † Dept. lpmo, femto-st Besançon, France, e-mail giordano@lpmo.edu 1 Applications include the measurement of the properties of materials and the observation of weak flicker-type physical phenomena, out of reach for other instruments. As an example, we measured the flicker noise of a by-step attenuator (−171 dB[rad 2 ]/Hz at f = 1 Hz) and of the ferrite noise of a reactive power divider (−173.7 dB[rad 2 ]/Hz at f = 1 Hz) without need of correlation. In addition, the real-time measurements can be exploited for the dynamical noise correction of ultrastable oscillators.

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Section: Automatic Carrier Suppressionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Advanced interferometric phase and amplitude noise measurements

Rubiola

Giordano

2002

Review of Scientific Instruments

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“…However, the sensitivity of Dick's frequency discriminator was limited by the lack of carrier suppression caused by imperfect matching of the cavity to the transmission line. The drawbacks of frequency discriminators based on critically coupled resonators were completely overcome in interferometric measurement systems [5,21,35,36,37,38,39]. By using interferometric signal processing, the phase noise floor of the X-band frequency discriminator was reduced to a level of −155 dBc/Hz at f = 1 kHz Fourier frequency without the use of cryogenic fluids.…”

Section: Interferometric Frequency Discriminatorsmentioning

confidence: 99%

“…For this reason most low-noise cancellation techniques have concentrated on reducing the phase noise. Recently the implementation of ultra-sensitive noise cancellation techniques have seen, for the first time, the reduction of phase noise below the amplitude noise of the oscillator [3,4,5].…”

Section: Loop Oscillator With Resonator In Transmissionmentioning

confidence: 99%

Low-Noise Microwave Resonator-Oscillators: Current Status and Future Developments

Ivanov

Tobar

Topics in Applied Physics

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Abstract. This contribution is devoted to principles of operation and design of low noise electromagnetic oscillators. We begin this chapter by introducing the concept of oscillator frequency stability and discussing both time and frequency domain approaches to its characterisation. We review most common experimental techniques used for improving the oscillator frequency stability. A particular attention is paid to applications of microwave circuit interferometry to precision measurements of oscillator frequency fluctuations. Finally, we analyse the future trends in the design of low noise microwave oscillators. This includes (i) interferometric suppression of oscillator power fluctuations and (ii) reduction of the oscillator frequency-temperature dependence by making use of an anisotropy of sapphire dielectric resonators.

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“…This cavity is integrated as a part of the feedback loop of the microwave oscillator and so is deemed an oscillator whose direct feedback loop is stabilized by a high Q cavity oscillator. An "interferometer" arm was introduced for increasing carrier suppression of the reflected signal from the cavity [48,49]. This arm vectorially adds to the already suppressed reflected signal (using a power combiner) a portion of the input signal fed into the cavity with the same amplitude as but opposite phase to that of the reflected signal.…”

Section: Sapphire Loaded Cavity Direct Feedback Oscillatormentioning

confidence: 99%

Low-noise x-band oscillator and amplifier technologies: comparison and status

Howe

Hati

Proceedings of the 2005 IEEE International Frequency Control Symposium and Exposition, 2005.

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-This study compares the phase noise of different classes of oscillators and amplifiers that work at X-band. Bestin-class results are presented based on recent measurements at NIST. In particular, comparisons are made between mature technologies of multiplied quartz, sapphire dielectric in whispering gallery mode (WGM), and air-dielectric-resonator stabilized RF oscillators in contrast to various configurations of optical electronic oscillators (OEO), cavity-stabilized, and atomstabilized optical-domain oscillators and femtosecond-lasercomb frequency synthesizers. This study also reports the status of classes of low-noise X-band amplifiers, since high-spectralpurity oscillators are constrained by amplifiers to varying degrees.Best-available low-noise X-band commercial amplifiers are compared with new feedforward, feedback, and array-gain test devices. Straight HBT (heterojunction bipolar transistors) and SiGe HBT technologies are compared in terms of phase noise. Results are for an operating frequency of 10 GHz.

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Applications of interferometric signal processing to phase-noise reduction in microwave oscillators

Cited by 82 publications

References 16 publications

Advanced interferometric phase and amplitude noise measurements

Advanced interferometric phase and amplitude noise measurements

Low-Noise Microwave Resonator-Oscillators: Current Status and Future Developments

Low-noise x-band oscillator and amplifier technologies: comparison and status

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