Gilles Cibiel

AM noise impact on low level phase noise measurements

The influence of the source AM noise in microwave residual phase noise experiments is investigated. The noise floor degradation problem, caused by the parasitic detection of this type of noise by an imperfectly balanced mixer, is solved thanks to a refinement of the quadrature condition. The parasitic noise contribution attributable to the AM to PM (phase modulation) conversion occurring in the device under test is minimized through the development of a dedicated microwave source featuring an AM noise level as low as -170 dBc/Hz at 10 kHz offset from a 3.5 GHz carrier.

A study of the correlation between high-frequency noise and phase noise in low-noise silicon-based transistors

The evidence of a predominant contribution of the transistor high-frequency noise in residual phase-noise data is demonstrated. This behavior is observed in devices in which the low-frequency noise contribution has been carefully minimized through an optimized bias network, and at offsets frequency above 10 kHz. The phase-noise behavior is then described through nonlinear noise-figure measurements. These results open the way to phase-noise minimization, with a different approach from the one used in most circuit design tools.

Optimization of an ultra low-phase noise sapphire-SiGe HBT oscillator using nonlinear CAD

In this paper, the electrical and noise performances of a 0.8 /spl mu/m silicon germanium (SiGe) transistor optimized for the design of low phase-noise circuits are described. A nonlinear model developed for the transistor and its use for the design of a low-phase noise C band sapphire resonator oscillator are also reported. The best measured phase noise (at ambient temperature) is -138 dBc/Hz at 1 kHz offset from a 4.85 GHz carrier frequency, with a loaded Q/sub L/ factor of 75,000.

Ultra low phase noise sapphire-SiGe HBT oscillator

A state of the art C-band oscillator is presented. It is based on a high Q WGM sapphire resonator combined with a low residual phase noise SiGe HBT amplifier. A two oscillator experiment performed on this system has revealed a phase noise level of -133 dBc/Hz at 1 kHz offset from the 4.85 GHz carrier, which is the best published phase noise result for a single loop, free running microwave oscillator.

Optical Scattering Induced Noise in Fiber Ring Resonators and Optoelectronic Oscillators

This paper reports both theoretical and experimental studies on nonlinear optical phenomena generated at very low thresholds in fiber ring resonators featuring ultrahigh quality factors. These studies are focused on two optical scattering phenomena: the Rayleigh and the Brillouin scatterings. The effects of these scattering phenomena on the phase noise of an optoelectronic oscillator based on the fiber ring resonator are detailed. A 30 dB reduction in the oscillator phase noise at 10 Hz offset frequency has been demonstrated by limiting the nonlinear scattering effects when using low input optical power. Moreover, a new high quality factor fiber ring resonator, optimized and immunized against some of these nonlinear optical effects, has been designed and an oscillator phase noise level of

Optical scattering noise in high Q fiber ring resonators and its effect on optoelectronic oscillator phase noise.

{-}50

Laser Stabilization on a Fiber Ring Resonator and Application to RF Filtering

dBc/Hz at 10 Hz offset frequency has been achieved.

Advanced bridge instrument for the measurement of the phase noise and of the short-term frequency stability of ultra-stable quartz resonators

Nonlinear phenomena occurring in an optical fiber ring resonator featuring ultrahigh Q factor are experimentally studied. The laser is locked onto the resonator, and the optical power induced in the resonator is controlled. The onset of the first stimulated Brillouin scattering wave occurs at an optical input power as low as -9 dBm in these resonators. When the resonator is used as the frequency reference device in an optoelectronic oscillator (OEO), it has been found that these parasitic signals mix with the OEO signal and degrade its phase noise. More than 20 dB improvement of the OEO phase noise has been demonstrated by limiting these nonlinear optical effects.

Tailoring of the free spectral range and geometrical cavity dispersion of a microsphere by a coating layer

The potential of optical fiber ring resonators for radio frequency (RF) or microwave signals filtering on optical carriers is demonstrated on a short length high Q resonator. The problem of the frequency shift due to the resonator self heating with the optical power is solved thanks to a Pound-Drever feedback loop. A multifrequency RF filter is obtained, with a frequency step of 205 MHz between resonances, and a 3-dB bandwidth of 2.4 MHz. This corresponds to the computed optical resonator 3-dB bandwidth, and thus represents an efficient technique for the measurement of ultrahigh Q optical resonators. In the field of microwave applications, the equivalent Q -factor obtained is particularly interesting in the upper microwave range.

Computation method for the short-term stability of quartz crystal resonators obtained from passive phase noise measures

This article reports on the advances in the characterization of an instrument intended to test 5 MHz and 10 MHz crystal resonators packaged in HC40 enclosure, that used for the high-stability space resonators. Improvements concern the design of new double ovens, the reduction of the residual carrier, a lower drift, and a modified calibration process. The instrument sensitivity, that is, the background phase noise converted into Allan deviation, is of 10-14.