Showing papers on "Phase noise published in 1994"

Theory of Magnetic Recording

Abstract: Preface 1. Overview 2. Review of magnetostatic fields 3. Inductive head fields 4. Medium magnetic fields 5. Playback process: general concepts, single transitions 6. Playback process: multiple transitions 7. Magnetoresistive heads 8. Record process: transition models 9. Record process: non-linearities and overwrite 10. Medium noise mechanisms: general concepts, modulation noise 11. Medium noise mechanisms: particulate noise 12. Medium noise mechanisms: transition noise References Index.

Delivering the same optical frequency at two places: accurate cancellation of phase noise introduced by an optical fiber or other time-varying path.

Abstract: Although a single-mode optical fiber is a convenient and efficient interface/connecting medium, it introduces phase-noise modulation, which corrupts high-precision frequency-based applications by broadening the spectrum toward the kilohertz domain. We describe a simple double-pass fiber noise measurement and control system, which is demonstrated to provide millihertz accuracy of noise cancellation.

Analysis of timing jitter in CMOS ring oscillators

Abstract: in this paper the effects of thermal noise in transistors on timing jitter in CMOS ring-oscillators composed of source-coupled differential resistively-loaded delay cells is investigated. The relationship between delay element design parameters and the inherent thermal noise-induced jitter of the generated waveform are analyzed. These results are compared with simulated results from a Monte-Carlo analysis with good agreement. The analysis shows that timing jitter is inversely proportional to the square root of the total capacitance at the output of each inverter, and inversely proportional to the gate-source bias voltage above threshold of the source-coupled devices in the balanced state. Furthermore, these dependencies imply an inverse relationship between jitter and power consumption for an oscillator with fixed output period. Phase noise and timing jitter performance are predicted to improve at a rate of 10 dB per decade increase in power consumption. >

Experimental and theoretical investigations of coherent OFDR with semiconductor laser sources

Abstract: Experimental and theoretical investigations of coherent optical-frequency-domain reflectometry using semiconductor laser sources are presented. Good agreement was found between the analysis of the signal-to-noise ratio due to the phase noise and the experimental results. The sensitivity limit due to the quantum noise is also described. Limitations due to the nonlinearity in the optical frequency sweep produced by the thermal-response time of the laser and mode hopping are investigated and compared with experimental results. Two interferometric methods to characterize the thermal-response time of the laser and their implementations are described. The effects of mode hopping in the optical-frequency sweep are compared to numerical simulations. A simple formula to predict the position of spurious peaks due to mode hopping are presented. A spatial resolution of 400 /spl mu/m over 10 cm was obtained by correcting the nonlinearity in the optical-frequency sweep by using an auxiliary interferometer. The Rayleigh backscattering was observed for the first time over more than 400 m of fiber using a DFB laser coupled to an external cavity. >

Optical orthogonal code-division multiple-access system .I. APD noise and thermal noise

Abstract: In an optical multiple-access system, overall system throughput efficiency add significant implementation cost-reduction would be achieved if many users could access a common optical channel at any time without control among users. Recently one such scheme, an optical orthogonal code division multiple-access system (OOCDMA), was introduced by Salehi et al. (1982) for the case of no noise. In this paper, some extensions of that work are presented, including the effects of avalanche photodiode (APD) noise and thermal noise as well as interference for the OOCDMA direct-detection receiver. Since it has been shown that an optical hard-limiter before the receiver correlator can reduce the interference effect for the OOCDMA system in the absence of noise, the hard-limiter role in the presence of thermal and APD noise is also examined. >

A digital frequency conversion and tuning scheme for microwave radio receivers and transmitters.

Abstract: A digital frequency upconversion and downconversion scheme for receivers and transmitters enables high resolution downconversion and upconversion, respectively, with low phase noise. A digital signal processor (DSP) (230) receives temperature measurement information from a temperature transducer associated with a reference oscillator (240), and also receives channel tuning and other information. The DSP adjusts the signal samples accordingly, without adjusting the operation of the oscillator. Additionally, the inventive filtering scheme, preferably implemented in an application specific integrated circuit (ASIC), receives digital filtering coefficient information, digital symbol timing phase control signals, and, in some cases, other information from the DSP. As a result, the scheme enables operation at 1 Hz resolution, with phase noise which is at least 33.5 dB down at 10 Hz in the case of downconversion, and at least 42 dB down at 10 Hz in the case of upconversion.

Reduction of background noise for speech enhancement

Abstract: Properties of human audio perception are used to perform spectral and time masking to reduce perceived loudness of noise added to speech signals. A signal is divided into blocks (2), passed through notch filters (4) to remove noise components and then appended to part of the previous block (6). An FFT (8) is then performed on the resulting block and the spectral components are fed to noise estimator (20). Each frequency component is then analyzed to determine whether it is noise. The frequency component's gain function is determined and a spectral valley filler (38) is used to processed the gain function after which the function is used to modify magnitude components of the FFT (12). In inverse FFT (14) then maps the signal back to the time domain to give a frame of noise-reduced signal.

PLL/DLL system noise analysis for low jitter clock synthesizer design

Abstract: This paper presents an analytical model for timing jitter accumulation in ring-oscillator based phase-locked-loops (PLL). The timing jitter of the system is shown to depend on the jitter in the ring-oscillator and an accumulation factor which is inversely proportional to the bandwidth of the phase-locked-loop. Further analysis shows that for delay-locked-loops (DLL), which use an inverter delay chain that is not configured as a ring-oscillator, there is no noise enhancement since noise jitter events do not contribute to the starting point of the next clock cycle. Finally, theoretical predictions for overall jitter are compared to behavioral simulations with good agreement. >

Frequency Synthesizer Design Handbook

Abstract: Building Blocks for Frequency Synthesis Using Phase-Locked Loops. Phase Noise and Its Impact Upon System Performance. Phase-Locked Loop Analysis for Continuous Linear Systems. Frequency Synthesis Using Sampled-Data Control Systems. Fast-Switching Frequency Synthesizer Design Considerations. Hybrid Phase-Locked Loops. MACSET -- A Computer Program for the Design and Analysis of Phase-Locked Loop Frequency Synthesizers. Fractional-N Frequency Synthesis.

Evading amplifier noise in nonlinear oscillators.

Abstract: Resonators driven to self-oscillation via active feedback play an important role in technology. Among the stochastic processes driving phase diffusion in such oscillators is noise from the feedback amplifier. Here a technique is described by which phase diffusion due to this noise can be suppressed. We have achieved a 10 dB reduction in phase diffusion by using the technique on an oscillator whose frequency-controlling element is a nonlinear mechanical resonator. The technique, in principle, provides a quantum nondemolition method of tracking a resonator's phase.

Terahertz optical frequency comb generation and phase locking of an optical parametric oscillator at 665 GHz.

Abstract: We have achieved efficient electro-optic phase modulation at high frequencies in a resonant modulator cavity We enhance modulation by matching the phase velocities of the optical and microwave fields in the modulator substrate and by placing the modulator inside an optical cavity that is resonant for the input optical beam and the generated sidebands An optical frequency comb with a span of 3 THz and at a spacing of 17 GHz is generated with 1 W of microwave power The terahertz comb is utilized to phase lock an optical parametric oscillator at a signal-idler difference frequency of 665 GHz

Behavioral simulation techniques for phase/delay-locked systems

Abstract: This paper presents behavioral simulation techniques for phase/delay-locked systems. Numerical simulation algorithms are compared and the issue of numerical noise is discussed. Behavioral phase noise simulation for phase/delay-locked systems is described. The role of behavioral simulation for phase/delay-locked systems in our top-down constraint-driven design methodology, and in bottom-up verification of designs, is explained with examples. Accuracy and efficiency comparisons with other methods are made. Simulation techniques are described in the framework of phase/delay-locked systems, but simulation methodology and the results attained in this work are applicable to the behavioral simulation of mixed-mode nonlinear dynamic systems. >

Methods and apparatus for digital frequency generation in atomic frequency standards

Abstract: A physics package interrogation signal can be digitally synthesized for use in an atomic frequency standard with one or more sets of integrally-related sub-multiples of a clock frequency in which one of the integrally-related sub-multiple frequencies is varied to provide frequency modulation between integrally-adjacent sub-multiple frequencies through the use of preloadable counters, the controlled delay and the synchronization of digital pulse trains and operation in plural modes. The method and apparatus can reduce false lock possibilities, optimize the ability of the physics package to remain locked, and reduce phase noise in the output of an atomic frequency standard.

SNR and spectral properties for a clipped DMT ADSL signal

Abstract: An accurate model developed to analyze the effects of clipping for a Gaussian signal with an arbitrary spectrum is presented. The model provides information on the reduction of the signal level, the total noise power due to clipping and the spectral properties of the noise. The method is applied to a discrete multitone (DMT) transmission system with parameters that are applicable for the asymmetric digital subscriber line (ADSL) technology. System calculations given to illustrate this approach show a 5 dB improvement in the signal-to-noise (SNR) ratio compared to previous work using an approximate analysis. >

Long-distance transmission at zero dispersion: combined effect of the Kerr nonlinearity and the noise of the in-line amplifiers

Abstract: Repeaterless long-distance transmission schemes are investigated in the presence of the Kerr nonlinearity and of the spontaneous-emission noise of the in-line amplifiers. Second- and higher-order dispersion coefficients are assumed to be zero. Criteria for optimizing the system performance are given.

Nearly quantum-limited timing jitter in a self-mode-locked Ti:sapphire laser.

Abstract: The experimentally measured timing jitter of a self-mode-locked Ti:sapphire laser is compared with the theoretically predicted quantum limit. Timing jitter figures of 150 fs (100–500 Hz) and 80 fs (500–5000 Hz), which approach the quantum limit, have been achieved by use of an improved cavity phase-locking technique.

A new approach to phase cancellation in repetitive control

Abstract: Effective repetitive control requires that the q-filter, placed within the internal model loop for robustness, have zero phase shift and that the phase shift of the plant be cancelled in the feedforward loop. Previously reported methods of phase cancellation use a moving average q-filter and zero-phase error tracking techniques for plant phase cancellation and are memory and processor intensive. The theory and methods of using a new method to cancel plant and filter phase shift in a repetitive control system are described. This method uses a tunable time advance and enables an analog/digital repetitive control loop to be used. Comparison with previously reported methods shows that it provides good phase cancellation, reduces low frequency repetitive disturbances, is easily tunable based on the closed-loop frequency response of the system without repetitive control, is less memory intensive, and is more easily implemented. >

A 6 GHz 68 mW BiCMOS phase-locked loop

Abstract: The design of a 6 GHz fully monolithic phase-locked loop fabricated in a 1 /spl mu/m, 20 GHz BiCMOS technology is described. The circuit incorporates a voltage-controlled oscillator that senses and combines the transitions in a ring oscillator to achieve a period equal to two ECL gate delays. A mixer topology is also used that exhibits full symmetry with respect to its inputs and operates with supply voltages as low as 1.5 V. Dissipating 60 mW from a 2 V supply, the circuit has a tracking range of 300 MHz, an rms jitter of 3.1 ps, and phase noise of -75 dBc/Hz at 1 kHz offset. >

High-Q thermoelectric-stabilized sapphire microwave resonators for low-noise applications

Abstract: Two low-noise high-Q sapphire-loaded cavity (SLC) resonators, with unloaded Q values of 2/spl times/10/sup 5/ and very low densities of spurious modes, have been constructed. They were designed to operate at 0/spl deg/C with a center frequency of 10.000000 GHz. The cavity was cooled with a thermoelectric (TE) Peltier element, and in practice achieved the required center frequency near 1/spl deg/C. The resonator has a measured frequency-temperature coefficient of -0.7 MHz/K, and a Q factor which is measured to be proportional to T/sup -2.5/. An upper limit to the SLC residual phase noise of /spl Lscr/ (100) Hz=-147 dBc/Hz, /spl Lscr/ (1 kHz)=-155 dBc/Hz, and /spl Lscr/ (10) kHz=-160 dBc/Hz has been measured. Also, we have created a free-running loop oscillator based on one of the SLC resonators, and measured a phase noise of /spl Lscr/(f)/spl sim/-10-30log [f] dBc/Hz between f=10 /Hz and 25 kHz, using the other as a discriminator. >

Phase noise analysis of the sapphire loaded superconducting niobium cavity oscillator

Abstract: Measured phase noise of two GaAs FET amplifiers and a varactor phase shifter at 9.7 GHz reveal that optimum bias conditions change when cooling from room to liquid helium temperatures. This understanding enables optimisation of the electronic noise in an all cryogenic tunable sapphire loaded superconducting cavity (SLOSC) X-band loop oscillator. The measured phase noise was limited by vibrations of the tuning mechanism. In a fixed frequency SLOSC oscillator the phase noise was limited by the amplifier noise, and has been measured to be /spl minus/140 dBc/Hz at 1 kHz from the unfiltered port of the loop oscillator. Comparison of component and oscillator phase noise allows us to calculate the phase noise at the filtered port to be /spl minus/175 dBc/Hz at 1 kHz offset. >

Phase noise measurement system and method.

Abstract: Three independent signal sources are used to statistically derive the power spectral density of the phase noise content of signals from each of them. This is accomplished by mixing each of the signals two at a time (i.e., signal one with signal two, signal one with signal three, and signal two with signal three) and capturing the resultant difference signals, such as with a waveform recorder, for example. A servo electronics loop is used to remove the carrier and any long term signal drift from the resultant difference signals. Statistical analysis is then used to compute the composite power spectral densities of the the resultant difference signals, and to solve for the individual power spectral densities of the original signals. The present system and method uses the mathematical relationships between the three sources that have similar magnitudes of phase noise, to compute the power spectral density of the noise content of signals from each source. The present system and method requires a minimum of interconnect hardware and only three inexpensive waveform recorders. Furthermore, the size, weight, and cost of producing the present phase noise test system is relatively low.

Residual phase noise measurements of VHF, UHF, and microwave components

Abstract: The results of residual phase noise measurements on a number of VHF, UHF, and microwave amplifiers, both silicon (Si) bipolar junction transistor (BJT) and gallium arsenide (GaAs) field effect transistor (FET) based, electronic phase shifters, frequency dividers and multipliers, etc., which are commonly used in a wide variety of frequency source and synthesizer applications are presented. The measurement technique has also been used to evaluate feedback oscillator components, such as the loop and buffer amplifiers, which can play important roles in determining an oscillator's output phase noise spectrum (often in very subtle ways). While some information has previously been published related to component residual phase noise properties, it generally focused on the flicker noise levels of the devices under test, for carrier offset frequencies less than 10 kHz. The work reported herein makes use of an extremely low noise, 500 MHz surface acoustic wave resonator oscillator (SAWRO) test source for residual phase noise measurements, both close-to-and far-from-the-carrier. Using this SAWRO-based test source at 500 MHz, we have been able to achieve a measurement system phase noise floor of -184 dBc/Hz, or better, for carrier offset frequencies greater than 10 kHz, and a system flicker phase noise floor of -150 dBc/Hz, or better, at 1 Hz carrier offset. The paper discusses the results of detailed residual phase noise measurements performed on a number of components using this overall system configuration. Several interesting observations related to the residual phase noise properties of moderate to high power RF amplifiers, i.e., amplifiers with 1 dB gain compression points in the range of +20 to +33 dBm, are highlighted. >

Noise in single-shot broadband coherent anti-Stokes Raman spectroscopy that employs a modeless dye laser.

Abstract: The noise in single-shot coherent anti-Stokes Raman (CARS) spectroscopy that employs a broadband modeless dye laser (MDL) is examined and the results are compared with those of a conventional dye laser. The noise of the dye-laser, the nonresonant CARS, and the resonant N(2) CARS signals are determined. The use of a MDL is shown to result in substantially reduced CARS noise when the CARS signal is generated with a single-mode pump laser, but only a marginal reduction of noise is observed with a multimode pump source The noise measurements are compared with theoretical predictions that are based on models that assume modes of random amplitudes and phases in the multimode laser sources. The combination of a MDL and a single-mode pump laser is shown to increase the precision of single-shot N(2) CARS temperature measurements.

An improved method of ADC jitter measurement

Abstract: This paper describes an original and highly accurate method for measuring analog to digital converters jitter. Previous works cover the "locked" histogram test which is generally used to estimate aperture uncertainty. This new method uses substraction techniques in a dual-channel sampling system. Synthesizers phase noise, voltage noise and ADC nonlinearities are removed to give the sum of both ADC's jitter. Then a third ADC is used to determine one ADC jitter value by 3 consecutive measurements. A significant improvement is demonstrated.

Acousto-optic liquid-crystal analog beam former for phased-array antennas

Abstract: A compact phased-array antenna acousto-optic beam former with element-level analog phase (0–2π) and amplitude control using nematic-liquid-crystal display-type technology is experimentally demonstrated. Measurements indicate >6-bit phase control and 52.6 dB of amplitude-attenuation control. High-quality error calibration and antenna sidelobe-levelcontrol is possible with this low-control-power analog beam former. Optical system options using rf Bragg cells or wideband Bragg cells are discussed, with the rf design being the current preferred approach. Transmit–receive beam forming based on frequency upconversion–downconversion by electronic mixing is introduced for the rf Bragg-cell beam former, and comparisons with digital beam forming are highlighted. A millimeter-wave signal generation and control optical architecture is described.

1.1 GHz oscillator using bondwire inductance

Abstract: Using the parasitic inductance usually associated with a bondwire in an IC package, a bipolar GHz LC-tuned oscillator is designed. Bondwires have very low series resistance and are thus suitable for high-Q applications. Measured results indicate very low phase noise and low power consumption.

MMIC phase locked L-S band oscillators

Abstract: We describe the design and measured performance of GaAs MMIC phase-locked oscillators (PLOs) operating concurrently at 1.353 GHz and 2.030 GHz. All the active components, including reference oscillator, phase/frequency comparators, charge pumps, voltage controlled oscillators (VCOs) and frequency dividers, are integrated on GaAs MMICs. The packaged MMICs are attached to a duroid mother board along with a small number of discrete components, resulting in a rugged dual PLO subassembly. Single sideband phase noise at 1 kHz offset is -87 dBc/Hz and -84 dBc/Hz, respectively. Phase lock is maintained over wide variations of temperature and power supply voltage.

Phase locked loop with reduced phase noise

Abstract: An accumulator-based phase locked loop reduces phase noise by shifting the energy of the phase noise to higher frequencies. A second accumulator is inserted between a first accumulator and a pulse generator to integrate a phase error from the first accumulator referenced to a clock signal. The output of the pulse generator is an approximation frequency signal that is compared with a comparable frequency signal derived from a reference signal to produce an error signal to control the frequency of the clock signal.