Phase Noise Values Research Articles

An upgraded interferometer-polarimeter system for broadband fluctuation measurements.

Measuring high-frequency fluctuations (above tearing mode frequencies) is important for diagnosing instabilities and transport phenomena. The Madison Symmetric Torus interferometer-polarimeter system has been upgraded to utilize improved planar-diode mixer technology. The new mixers reduce phase noise and allow more sensitive measurements of fluctuations at high frequency. Typical polarimeter rms phase noise values of 0.05°-0.07° are obtained with 400 kHz bandwidth. The low phase noise enables the resolution of fluctuations up to 250 kHz for polarimetry and 600 kHz for interferometry. The importance of probe beam alignment for polarimetry is also verified; previously reported tolerances of ≤0.1 mm displacement for equilibrium and tearing mode measurements minimize contamination due to spatial misalignment to within acceptable levels for chords near the magnetic axis.

Design of low power CMOS LC VCO for direct conversion transceiver

A low power 1.2 GHz LC differential voltage-controll ed oscillator (VCO) is designed for a direct conversion transceiver in 130 nm CMOS processes. It consists of a complementary current reuse structure and LC tank circuit. To produce a good tuning range and reduce losses in the tank circuit, modied inversion mode PMOS varactors and an on-chip inductor are designed with a better quality factor. The icker noise is reduced by the PMOS tail current source connected in parallel with the capacitance. The 1.2 GHz LC VCO achieves a phase noise value of {132 dBc/Hz at 1 MHz offset and the tuning range of the oscillator is from 1.128 to 1.27 GHz for the control voltage, tuning from 0 to 1.5 V. It dissipates 245 W power at 0.8 V supply voltage and thegure of merit is calculated as {199.7 dBc/Hz.

Frequency-Tuning Negative-Conductance Boosted Structure and Applications for Low-Voltage Low-Power Wide-Tuning-Range VCO

A frequency-tuning negative-conductance (-G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> ) boosted structure and applications for a voltage-controlled oscillator (VCO) is presented in this paper. Analog tuning varactors connected to a -G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> boosted structure is proposed to significantly alleviate the limitation of the tuning range for the -G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> boosted structure, resulting in a low-voltage low-power wide-tuning-range VCO. Based on the proposed architecture, the fabricated 0.18-μm CMOS VCO exhibits a measured 49.8% tuning range. Operating at 0.65 V low supply voltage, the VCO core consumes 2.37-mW dc power. At this bias condition, the measured average value of phase noise for all frequency ranges is -115.1 dBc/Hz at 1-MHz offset from the carriers. Relative to recently published wide-tuning-range CMOS VCOs, the proposed VCO simultaneously achieves low supply voltage, low dc power dissipation, low phase noise, and a wide tuning range, leading to a good figure-of-merit (FOM) and FOM including the tuning range. Furthermore, formulas of analysis for the proposed frequency-tuning -Gm boosted structure and wide VCO tuning range are presented, and the mechanisms are validated by experiments.

On discrete-time modeling of the filtered and symbol-rate sampled continuous-time signal affected by Wiener phase noise

This paper investigates the differences between the symbol-spaced discrete-time Wiener phase noise channel model, commonly assumed in the literature to represent the effect of phase noise, and that obtained by symbol-rate sampling the filtered continuous-time received signal affected by continuous-time Wiener phase-noise. In particular, for comparison, we consider some statistical tests to check temporal and distributional properties of the two models. We show that the fit between the two models is very good even for quite strong values of phase noise. The main result is that when the standard deviation of the discrete-time Wiener phase noise increment σPN is below a threshold of approximately σ¯PN≃0.1rad, the discrete-time Wiener model provides a good approximation to the actual symbol-spaced sampled filtered signal affected by continuous-time Wiener phase noise. We show that when σPN is below σ¯PN the ratio between the power of the signal and the power of the model mismatch is greater than 20dB. Simulation results are also presented to compare bit error rates of the two models in case of QPSK and 16-QAM transmission and to compare the power spectral densities of their associated complex exponential phase noises. Our results suggest that the discrete-time Wiener phase noise model can be adopted for many real-world systems, where, according to experimental results available in the literature, σPN in the order of 0.1rad is rarely found even when the nonlinearity of the optical channel is deeply stressed.

Novel Rx IQ mismatch compensation considering laser phase noise for CO-OFDM system

In this paper, a novel compensation scheme for receiver (Rx) in-phase/quadrature (IQ) mismatch is proposed in coherent optical orthogonal frequency division multiplexing (CO-OFDM) system in the presence of laser phase noise. In this scheme, laser phase noise and channel distortion were combined as a new channel transfer factor, the IQ mismatch factor and initial channel transfer factor can be estimated independently based on the relationship of IQ mismatch factors. And the channel transfer factor can be updated on a symbol-by-symbol basis which retrieves an estimation of the phase noise value by extracting and averaging the phase drift of all OFDM sub-channels. Numerical results indicate that when the phase and amplitude mismatch are 10° and 2dB respectively, a 1.6dB optical signal-to noise ratio is improved at laser linewidth of 60kHz. Furthermore, the complexity of the proposed method is analyzed in terms of the number of required complex multiplications per bit.

Joint frequency domain equalisation and phase noise estimation for single‐carrier modulations in doubly‐selective channels

In this study the authors propose a novel joint detection and phase noise estimation scheme suited for severely time-dispersive channels. The authors consider single-carrier modulations combined with frequency domain equalisation schemes where the wireless transmission is impaired with phase noise. An iterative frequency-domain equaliser is assumed on the receiver side and the phase noise is estimated and compensated for after the equalisation step and within each iteration of the equaliser. In fact, by exploiting the Gaussianity of the equaliser output the authors are able to track the phase noise using stochastic recursive filtering techniques. These techniques share the same dynamic state-space (DSS) model. The observation equation corresponds to the measurement of the phase noise of a digitally-modulated signal affected by additive white Gaussian noise, and the dynamics equation corresponds to the Wiener–Lévy model for the phase noise. Supported on this DSS model the authors aim at estimating the unknown phase noise value given all observations up to the current time instant. In a Bayesian context this represents estimating recursively in time the filtering and the predictive distributions. From these distributions a minimum mean-squared error estimate of the phase noise is determined.

Waveform design solutions for EHF broadband satellite communications

The problematic RF environment experienced by broadband satellite communications at EHF frequency bands, in particular Q/W bands, call for the use of novel waveforms. This paper presents a detailed comparison of several waveforms in presence of nonlinear distortions and typical values of phase noise introduced at Q/W band. Two main types of waveforms have been compared: Constant Envelope multicarrier waveforms (CE-OFDM and CE-SCFDMA) and single carrier impulse-based waveforms (TH-UWB, DS-UWB and PSWF-based PSM). This comparison will allow to draw some practical guidelines for the waveforms design of EHF broadband satellite communications.

A Low-Voltage Low-Power Wide-Tuning-Range Hybrid Class-AB/Class-B VCO With Robust Start-Up and High-Performance ${\rm FOM}_{ T}$

This paper proposes a hybrid class-AB/class-B voltage-controlled oscillator (VCO) with low voltage, low power, and a wide tuning range. The class-AB VCO core is designed to ensure robust start-up of the class-B VCO core. Featuring a high-efficiency class-B VCO core, the combination of class-AB/class-B VCO cores consumes low dc power. Based on the proposed architecture, the fabricated 0.18-μm CMOS VCO exhibits a measured tuning range of 25.6%. Operating at a low supply voltage of 0.75 V, the hybrid class-AB/class-B VCO cores consume a low total dc power of 2.4 mW. In this bias condition, the measured average value of phase noise for all frequency ranges is -101.4 dBc/Hz at 1-MHz offset from the carriers. Compared to recently published wide-tuning range VCOs, the proposed hybrid class-AB/class-B VCO simultaneously achieves a low supply voltage, a low dc power dissipation, and wide tuning range, leading to a good figure-of-merit including the tuning range (FOMT). In addition, the theories for analyzing the VCO are given in detail, and the mechanisms are validated by experiments.

Design of optimal nano-CMOS differential VCO for RF applications

In the design of radio frequency (RF) circuits fast prototyping with optimal performance is a challenging task for designers. The noise consideration in the differential voltage controlled oscillator (DVCO) is very much vital in its design. The present work focuses on the design of low phase noise and low power robust nano-CMOS differential voltage controlled oscillator (DVCO) for a desired frequency of oscillation 2.4 GHz. Constrained multi-objective optimisation, infeasibility driven evolutionary algorithm (IDEA) is used to minimise the phase noise and power consumption simultaneously. In this work, the phase noise is formulated to inherently account for the flicker noise along with the thermal noise and optimised along with power consumption by IDEA. The optimal performing circuit is synthesised using GPDK-90 nm 1P9M process library. The frequency of oscillation obtained in the parasitic inclusive design of the differential VCO is 2.399513658 GHz which is in good agreement with the target frequency with negligible deviation and the corresponding optimum values of power consumption and phase noise recorded are 845.5095 µW and 79.67 dBc/Hz at 1 MHz offset, respectively.

Phase Noise of the Radio Frequency (RF) Beatnote Generated by a Dual-Frequency VECSEL

We analyze, both theoretically and experimentally, the phase noise of the radio frequency (RF) beatnote generated by optical mixing of two orthogonally polarized modes in an optically pumped dual-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). The characteristics of the RF phase noise within the frequency range of 10 kHz - 50 MHz are investigated for three different nonlinear coupling strengths between the two lasing modes. In the theoretical model, we consider two different physical mechanisms responsible for the RF phase noise. In the low frequency domain (typically below 500 kHz), the dominant contribution to the RF phase noise is shown to come from the thermal fluctuations of the semicondutor active medium induced by pump intensity fluctuations. However, in the higher frequency domain (typically above 500 kHz), the main source of RF phase noise is shown to be the pump intensity fluctuations which are transfered to the intensity noises of the two lasing modes and then to the phase noise via the large Henry factor of the semiconductor gain medium. For this latter mechanism, the nonlinear coupling strength between the two lasing modes is shown to play an important role in the value of the RF phase noise. All experimental results are shown to be in good agreement with theory.

State-of-the-art RF signal generation from optical frequency division

We present the design of a novel, ultralow-phase-noise frequency synthesizer implemented with extremely-low-noise regenerative frequency dividers. This synthesizer generates eight outputs, viz. 1.6 GHz, 320 MHz, 160 MHz, 80 MHz, 40 MHz, 20 MHz, 10 MHz and 5 MHz for an 8 GHz input frequency. The residual single-sideband (SSB) phase noises of the synthesizer at 5 and 10 MHz outputs at 1 Hz offset from the carrier are -150 and -145 dBc/Hz, respectively, which are unprecedented phase noise levels. We also report the lowest values of phase noise to date for 5 and 10 MHz RF signals achieved with our synthesizer by dividing an 8 GHz signal generated from an ultra-stable optical-comb-based frequency division. The absolute SSB phase noises achieved for 5 and 10 MHz signals at 1 Hz offset are -150 and -143 dBc/Hz, respectively; at 100 kHz offset, they are -177 and -174 dBc/Hz, respectively. The phase noise of the 5 MHz signal corresponds to a frequency stability of approximately 7.6 × 10(-15) at 1 s averaging time for a measurement bandwidth (BW) of 500 Hz, and the integrated timing jitter over 100 kHz BW is 20 fs.

Performance Analysis of Energy-Efficient BBPLL-Based Sensor-to-Digital Converters

Highly digital-oriented architectures for sensor interfaces are very interesting for their high energy efficiency, especially in smaller CMOS technologies which offer low-voltage design. This paper presents the analysis of a Bang-Bang Phase-Locked Loop Sensor-to-Digital Converter (BBPLL SDC). The highly digital-oriented BBPLL offers advantages such as the low chip area, excellent scalability towards smaller technologies, robustness towards process variations and low-voltage possibilities, making this architecture very interesting for energy-efficient applications. Theoretical analysis of the structure shows that the BBPLL SDC resembles a -modulator with first-order quantization noise shaping due to the frequency-to-phase conversion of the oscillators. Oscillator phase noise however plays an important role in the analysis and limits the SNR in practical implementations. To validate the theoretical analysis, a state-variable-based non-linear Matlab model has been developed, including non-idealities such as phase noise, non-linearity and mismatch. Based on practically achievable phase noise values of state of the art oscillators, simulations show that resolutions up to 110 dB can be achieved. An estimation of the power consumption of the oscillators, based on state of the art figures, results in energy-efficient designs beyond the state of the art with moderate resolutions of 40-80 dB SNR, while high resolutions of 80-110 dB demand higher power consumption in the oscillators, resulting in designs with lower energy efficiency, but still competitive with the current state of the art. A design strategy for both an energy-efficient and a high-performance BBPLL SDC is provided.

Experimental Study of a novel adaptive decision-directed channel equalizer in 28 GBaud RGI-DP-CO-OFDM transport systems

We report and experimentally investigate the performance of an adaptive decision-directed channel equalizer (ADDCE) in reduced-guard-interval dual-polarization coherent-optical orthogonal-frequency-division-multiplexing (RGI-DP-CO-OFDM) transport systems. ADDCE retrieves an estimation of the phase noise value after an initial decision making stage by extracting and averaging the phase drift of all OFDM sub-channels. Moreover, it updates the channel transfer matrix on a symbol-by-symbol basis. We experimentally compare the performance of the ADDCE and the conventional equalizer (CE) combined with maximum-likelihood (ML) phase noise compensation and inter-subcarrier-frequency-averaging (ISFA) algorithms. The study is conducted at 28 GBaud for RGI-DP-CO-OFDM systems with quadrature-phase-shift-keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) formats. Using ADDCE, zero-overhead laser phase noise compensation is accomplished and the overhead due to training symbol (TSs) insertion is significantly reduced. In addition, ADDCE offers a superior performance over the CE in the presence of synchronization timing errors and residual chromatic dispersion (CD). We also achieve a longer transmission distance than when using the CE. At a forward-error-correction (FEC) threshold of 3.8 × 10−3, using a cumulative overhead of less than 2.6%, transmission distances of 5500 km and 400 km were achieved for the cases of QPSK and 16-QAM RGI-DP-CO-OFDM, respectively.

Digital detection and processing of multiple quadrature harmonics for EPR spectroscopy

A quadrature digital receiver and associated signal estimation procedure are reported for L-band electron paramagnetic resonance (EPR) spectroscopy. The approach provides simultaneous acquisition and joint processing of multiple harmonics in both in-phase and out-of-phase channels. The digital receiver, based on a high-speed dual-channel analog-to-digital converter, allows direct digital down-conversion with heterodyne processing using digital capture of the microwave reference signal. Thus, the receiver avoids noise and nonlinearity associated with analog mixers. Also, the architecture allows for low-Q anti-alias filtering and does not require the sampling frequency to be time-locked to the microwave reference. A noise model applicable for arbitrary contributions of oscillator phase noise is presented, and a corresponding maximum-likelihood estimator of unknown parameters is also reported. The signal processing is applicable for Lorentzian lineshape under nonsaturating conditions. The estimation is carried out using a convergent iterative algorithm capable of jointly processing the in-phase and out-of-phase data in the presence of phase noise and unknown microwave phase. Cramér–Rao bound analysis and simulation results demonstrate a significant reduction in linewidth estimation error using quadrature detection, for both low and high values of phase noise. EPR spectroscopic data are also reported for illustration.

Zero-overhead phase noise compensation via decision-directed phase equalizer for coherent optical OFDM

We report and investigate the feasibility of zero-overhead laser phase noise compensation (PNC) for long-haul coherent optical orthogonal frequency division multiplexing (CO-OFDM) transmission systems, using the decision-directed phase equalizer (DDPE). DDPE updates the equalization parameters on a symbol-by-symbol basis after an initial decision making stage and retrieves an estimation of the phase noise value by extracting and averaging the phase drift of all OFDM sub-channels. Subsequently, a second equalization is performed by using the estimated phase noise value which is followed by a final decision making stage. We numerically compare the performance of DDPE and the CO-OFDM conventional equalizer (CE) for different laser linewidth values after transmission over 2000 km of uncompensated single-mode fiber (SMF) at 40 Gb/s and investigate the effect of fiber nonlinearity and amplified spontaneous emission (ASE) noise on the received signal quality. Furthermore, we analytically analyze the complexity of DDPE versus CE in terms of the number of required complex multiplications per bit.

X-band low phase noise in-phase and out-of-phase injection-locked push-push DRO

An X-band push–push dielectric resonator (DR) oscillator with injection locking capability has been developed.Two injection locking methods, i.e., the in-phase method and the out-of-phase method, are studied. It is found that the out-of-phase method has wider locking range and much less effects on fundamental suppression than that of the in-phase method. The oscillator generates an output power of 9.5 dBm at 12.4 GHz and has a fundamental suppression of 32.5 dBc. Despite using a high quality (Q) factor DR, wide locking range has been obtained. SiGe HBTs with good flicker noise performance were chosen for low phase noise design. The phase noise values of the free running oscillator are −104.4 dBc/Hz, −120.2 dBc/Hz, and −142.6 dBc/Hz at 10 kHz, 100 kHz, and 1 MHz offsets from the carrier frequency, respectively. The phase noise performance is superior or comparable to the reported designs. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2448–2452, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25510

A strip extracting algorithm for phase noise measurement and coherent beam combining of fiber amplifiers

We present a strip extracting algorithm (SEA) for detecting and locking the phase noise of fiber amplifiers. Based on the algorithm, the phase noise of a 10 W Yb fiber amplifier is obtained and locked with an active segment mirror (ASM) and a high-speed CCD camera. Experimental results indicate that within the first 3 seconds after turn-on transients occur the amplitude of phase noise exceeds 20 waves, whereas in thermal steady-state operation it amounts to only several waves for the same time span. After phase locking, the Peak-to-Valley (PV) value of phase noise is close to ∼1/10λ (λ=1064 nm), and the control bandwidth of the system is ∼25 Hz.

An integrated 8-12 GHz fractional-N frequency synthesizer in SiGe BiCMOS for satellite communications

We present an integrated fractional-N low-noise frequency synthesizer for satellite applications. By using two integrated VCOs and combining digital and analog tuning techniques, a PLL lock range from 8 to 12 GHz is achieved. Due to a small VCO fine tuning gain and optimized charge pump output biasing, the phase noise is low and almost constant over the tuning range. All 16 sub-bands show a tuning range above 900 MHz each, allowing temperature compensation without sub-band switching. This makes the synthesizer robust against variations of the device parameters with process, supply voltage, temperature and aging. The measured phase noise is ?87 dBc/Hz and ?106 dBc/Hz at 10 kHz and 1 MHz offset, respectively. In integer-N mode, phase noise values down to ?98 dBc/Hz at 10 kHz and ?111 dBc/Hz at 1 MHz offset, respectively, were measured.

Multifrequency Pierce Oscillators Based on Piezoelectric AlN Contour-Mode MEMS Technology

This paper reports on the first demonstration of multifrequency (176-, 222-, 307-, and 482-MHz) oscillators based on the piezoelectric AlN contour-mode microelectromechanical systems technology. All the oscillators show phase noise values between -88 and -68 dBc/Hz at 1-kHz offset frequency from the carriers and phase noise floor values as low as -160 dBc/Hz at 1 MHz offset. The same Pierce circuit design is employed to sustain oscillations at the four different frequencies; on the other hand, the oscillator core consumes 10 mW. The AlN resonators are currently wire bonded to the integrated circuit realized in the AMIS 0.5-¿m 5-V complimentary metal-oxide-semiconductor process. Limits on phase noise and power consumption are discussed and compared with other competing technologies. This paper constitutes a substantial step forward toward the demonstration of a single-chip multifrequency reconfigurable timing solution that can be used in wireless communications and sensing applications.

Fundamental wave phase-locked dual-band push-push DRO using out-of-phase Wilkinson power combiner

A new push-push phase-locked dielectric resonator oscillator (PLDRO) with dual-band (C/Ku) output capability is presented. An out-of-phase Wilkinson power combiner is used to provide the fundamental ( f 0 ) output. The phase-locking is implemented at f 0 as an alternative to direct locking the push-push output frequency (2 f 0 ) using prescalers. The push-push PLDRO has shown a fundamental suppression of 35.12 dBc and a second-harmonic suppression of 34.77 dBc at the 2 f 0 output and the f 0 output, respectively. Experimental results also indicate a maximum spur level of -77.4 dBc, and phase noise values of -109.6 and -143 dBc/Hz at 10 kHz and 1 MHz offsets, respectively, from a 12.6 GHz carrier.