Phase Noise Response Research Articles

Si/Ge phototransistor with responsivity >1000A/W on a silicon photonics platform.

In this article, we report a Si/Ge waveguide phototransistor with high responsivity and low dark current under low bias voltages, due to an engineered electric field distribution. The photodetector consists of n-i-p-i-n doping regions and shows a responsivity of 606 A/W at 1 V bias, and 1032 A/W at 2.8V bias with an input optical power of -50 dBm, and dark current of 4 µA and 42 µA respectively. This is achieved by placing two p+-doped regions in the silicon slab region beneath the Ge epitaxial layer. A measured small signal -3 dB bandwidth of 1.5 GHz with a -80 dBc/Hz phase noise response at 1 KHz frequency offset were demonstrated experimentally.

Analysis of high-order sub-harmonically injection-locked oscillators

AbstractHigh-order sub-harmonically injection-locked oscillators have recently been proposed for low phase-noise frequency generation, with carrier-selection capabilities. Though excellent experimental behavior has been demonstrated, the analysis/simulation of these circuits is demanding, due to the high ratio between the oscillation frequency and the frequency of the input source. This work provides an analysis methodology that covers the main aspects of the circuit behavior, including the detection of the locking bands and the prediction of the phase-noise spectral density. Initially, the oscillator in the presence of a multi-harmonic input source is described with a reduced-order envelope-domain formulation, at the oscillation frequency, based on an oscillator-admittance function extracted from harmonic-balance simulations. This allows deriving an expression for the oscillation phase shift with respect to the input source, and the average of this phase shift is shown to evolve continuously in the distinct synchronization bands obtained when varying a tuning voltage. This property can be used to detect the locking bands in circuit-level envelope-domain simulations, which, as shown here, can be done through different Fourier decompositions and sampling rates. The phase noise of the high-order sub-harmonic injection-locked oscillator under an arbitrary periodic input waveform is investigated in detail. The frequency response to the noise sources is described with a semi-analytical formulation, relying on the oscillator-admittance function in injection-locked conditions. The input noise is derived from the timing jitter of the injection source and the phase-noise response is shown to exhibit a low-pass characteristic, which initially follows the up-converted input noise and then the oscillator own noise sources. A method is proposed to identify the key parameters of the derived phase-noise spectrum from envelope-domain simulations. The various analysis methodologies have been applied to a prototype at 2.7 GHz at the sub-harmonic order N = 30 which has been manufactured and measured.

A comprehensive analysis on differential cross-coupled CMOS LC oscillators via multi-objective optimization

CMOS differential cross-coupled LC oscillators are widely used due to their superior phase noise performance. Even though the number of circuit elements is small, the design process is not trivial due to the complicated trade-off between the phase noise and power consumption. Conventionally, cross-coupled oscillators can be constructed by using only PMOS or only NMOS devices or using both (CMOS). The topology selection is mostly based on either theoretical calculations or experimental (measurement/simulation) results on specific solution points reported in the literature; however, there is no comprehensive analysis on comparison of these topologies in the literature. Also, there are several efforts on improving the phase noise response such as conventional tail noise filtering (using a tail capacitor or LC filter) and sinusoidal tail shaping. Yet, the cost-performance effectiveness of such techniques has not been well-discussed in the literature. In this study, performances of different differential cross-coupled LC oscillators are examined using a parasitic-aware multi-objective RF circuit synthesis tool. PMOS, NMOS, and CMOS types of oscillators were synthesized and performances of those circuits were thoroughly demonstrated. The synthesis results were validated by performing post-layout simulations for different solutions located on the Pareto optimal front (POF). To observe the effect of the other layout parasitics, the CMOS oscillator was also optimized including a parasitic netlist of a drawn layout. The effect of using LC tank with centre-tapped inductor on oscillator performance was also investigated. Furthermore, effectiveness of several phase noise reduction techniques; tail capacitor filtering, tail LC filtering, and sinusoidal noise shaping were demonstrated and discussed in detail.

RF injection locked 18 GHz regeneratively mode-locked semiconductor laser.

In this manuscript, a semiconductor based fiber ring cavity mode-locked laser regeneratively driven at 18 GHz is presented. The optical spectrum of the laser is centered at 1578 nm. The laser is RF injection locked via an external source at 18 GHz. The phase noise of the mode-locked laser is measured and the integrated timing jitter was found to be 10.8 fs (from 100 Hz to 20 MHz) and 13.3 fs (from 100 Hz to Nyquist frequency). The integrated amplitude fluctuation (from 100 Hz to 20 MHz) was less than 0.02%. The laser phase and amplitude noise responses to various injected RF power levels were also investigated. The injection RF power has significant effect on the phase noise and the best jitter value is around 40 dB lower than the cavity regenerated RF power.

MeerKAT time and frequency reference optical network: Preliminary design analysis


 
 
 The MeerKAT telescope is a precursor to the Square Kilometre Array, which will rely on optical fibres to link the telescope receivers to a central processor point. The main aspects to consider for the fibre transport are astronomical data transmission as well as timing, monitoring and control. The astronomical data streams from individual dishes to a central building, while the clock signal is distributed from a central point to remote dishes in the telescope array. The MeerKAT telescope, for instance, demands highly accurate and stable clock distribution over up to 12 km of optical fibre to remote dishes. The clock distribution is required for digitisation of astronomical signals. Phase stability is thus critical both for short-term and long-term requirements. In this work, we focused on the short-term stability. Phase noise measurements were performed on optical transmitters used to distribute the clock signals so as to ascertain their contribution to the overall clock jitter of the system. A maximum jitter requirement of 130 fs for a 1.712-GHz clock signal for MeerKAT time and reference is achieved using a distributed feedback laser. We found that with optimised modulation depth, additional passive optical components in the link do not significantly degrade the phase noise response. A distributed feedback laser was proven to be a suitable optical source that will meet the performance and link budget requirements for the MeerKAT telescope.
 
 
 
 
 Significance: 
 
 
 
 A distributed feedback laser is recommended for the design of the MeerKAT time and reference system as it is a suitable optical source that will meet the performance and link budget requirements.
 
 
 

Interference Analysis for OFDM Transmissions in the Presence of Time-Varying Channel Impairments

This paper is concerned with the detrimental effect of phase noise on the performance of orthogonal frequency division multiplexing (OFDM) transmissions over time-selective channels. In the literature, most of the existing papers analyze the performance of OFDM systems in the presence of either time-selective channels or phase noise. Unlike the existing studies, this paper formulates an approximate expression of signal-to-interference-plus-noise ratio (SINR) at an OFDM receiver in the presence of both phase noise and time-selective channel response. The formulated SINR expression can be used as a guideline in determining appropriate OFDM transmission settings under a given quality-of-service (QoS) requirement. To illustrate the tightness of the approximate SINR formulation, empirical and theoretical values of SINR under different OFDM system settings are presented in this paper.

Frequency chirp and mode partition induced mutual constraint on the side-band phase noise of a mode-locking WRC-FPLD fiber ring self-started with a lengthened feedback loop

The specific mutual constraint effect of frequency chirp and mode partition on the side-band phase noise and timing jitter is theoretically and experimentally analyzed in a harmonically mode-locked weak-resonant-cavity Fabry–Perot laser diode (WRC-FPLD) fiber ring self-started by fiber-coupled optoelectronic feedback at 10 GHz with a lengthened loop. By inserting a 100 m long single-mode fiber into the feedback loop to self-start the mode-locking, minimal single-side-band phase noise of −70 dBc Hz−1 and −125 dBc Hz−1 are obtained at 100 Hz and 1 MHz offset, respectively. The optimized pulse-train exhibits a timing jitter of 0.67 ps and a pulsewidth of 18.5 ps. A significant degradation is observed for feedback loop lengths longer than 200 m due to the enhanced mode-partition noise contributed by the fiber-ring cavity incorporated in the WRC-FPLD. The theoretical model shows that the mutually coupled fiber-ring cavity and the optoelectronic feedback loop could provide a mode-locking pulse with a minimum phase noise of −135 dBc Hz−1 under the compromise of phase noise responses between the fiber-ring cavity and the feedback loop. These two factors hinder the improvement expected from the longer feedback loop and higher Q-value because the mode-partition noise is greatly enlarged when the multi-mode pulse experiences serious dispersion during distant transmission in the fiber. Under such a mutual constraint, the optimized return-to-zero (RZ) pulsed carrier is on–off keying (OOK) non-RZ data by 10 Gbit s−1, showing a high signal to noise ratio of 11 dB to achieve a receiving sensitivity of −19.2 dBm at a bit error rate (BER) of 10−9. When using the RZ pulsed carrier for data transmission at 10 Gbit s−1 in a passive optical network with a dense wavelength division multiplexing channelization of 200 GHz, the RZ-OOK data-stream still exhibits an error-free performance at a receiving power sensitivity as low as −17 dBm, even though a power penalty of 2.5 dB is added into the BER response.

Stability and Phase-Noise Analysis of Pulsed Injection-Locked Oscillators

An investigation of the stability and phase noise of oscillators driven with pulsed signals is presented. The aim is to generalize the theory of sinusoidal injection-locked oscillators to the case of oscillators driven with multiharmonic sources. As will be shown, under the pulse injection, a multiresonance phenomenon occurs in the circuit, leading to broad ultra-subharmonic synchronization bands. The stability phenomena delimiting these bands are analyzed through the detection of the oscillation-burst maxima, in the time domain, and the results are validated with pole-zero identification. The rich nonlinear dynamics is investigated, with detailed explanations of the various bifurcations detected. The phase-noise response of the pulse injection-locked oscillator is analyzed and related to the stability properties of the synchronized steady state. The investigation is illustrated through application to a pulse injection oscillator at 5.7 GHz.

Practical Signal Recovery of WLAN OFDM Signals in the Presence of IQ Imbalance, Phase Noise, and Unknown Channel Frequency Response

We propose two solutions to combat against the IQ imbalance, multipath fading, phase noise, and additive white Gaussian noise in the IEEE 802.11a environment. We show by computer simulations that our proposed least squared (LS) and least mean squared (LMS) solutions outperform, in terms of bit error rate, the solutions in some other papers. Our LMS solution, which does not require matrix inversion, is more computational efficient than our LS solution. Hence, our LMS solution is of practical use.

RF VCO tuning using MEMS piezoelectric actuated variable inductors

This paper presents a study on the use of microsystems technology in the design of radio frequency voltage-controlled oscillators. In particular, the application of a micro-electro-mechanical systems (MEMS) based variable inductor for frequency tuning purposes is presented. Although traditionally a MEMS variable inductor is considered as a means to extend the tuning range, in this work it is shown that with correct inductor design it is also possible to facilitate and improve the voltage-controlled oscillator design in terms of phase noise response and power consumption in comparison to a design based on standard capacitive tuning.

Design of SIPC‐based complementary LC‐QVCO in 0.18‐μm CMOS technology for WiMAX application

PurposeThe purpose of this paper is to design and realize a low‐phase noise, high‐output power, and high‐tuning range, fully integrated source injection parallel coupled (SIPC)‐based inductor‐capacitor (LC)‐quadrature voltage controlled oscillator (QVCO) covering WiMAX frequency range in 0.18‐μm deep submicron CMOS technology.Design/methodology/approachA pMOS based‐SIPC LC‐QVCO topology is realized with the center frequency of 2.58 GHz. On chip spiral inductor is integrated with substantial quality factor, Q coupled with underlying pattern ground shield (PGS) shielding. An enhanced tuning range is achieved by integrating the diode connected MOS‐based varactors. The CMOS‐based autonomous SIPC LC‐QVCO circuit was characterized for its output phase noise, tuning range and power spectrum response via wafer probing, utilizing a signal source analyzer (Agilent E5052 A).FindingsA quadrature oscillator catering to the needs of local oscillator (LO) generation covering the frequency range of WiMAX is realized. The parallel coupled architecture adapts direct source coupling, bypassing the LC resonator tank and relaxes the close in phase noise up‐conversion. The design consumes 2.19 mm2 of active chip area and measures a phase noise of −114.34 dBc/Hz at 1 MHz of offset frequency with 2.67 GHz of output frequency at 0.9 V of input tuning voltage. The corresponding output power measures to be −10.1 dBm, well suited for mixer hard switching. The design is realized in one poly, six metal 0.18‐μm standard CMOS technology.Research limitations/implicationsOwing to convergence discrepancy in the analysis, a diode‐connected MOS varactor is adapted in contrary to the accumulation mode MOS varactors with superior tuning range.Practical implicationsThe designed SIPC LC‐QVCO is of need in the generation of low‐phase noise, highly matched quadrature LO generation covering the WiMAX frequency range. The adapted parallel coupling also relaxes the voltage headroom limitation.Originality/valueThis paper shows how a fully integrated CMOS‐based SIPC LC‐QVCO architecture is adapted with low‐output phase noise and low voltage headroom consumption covering the WiMAX frequency range.

Phase Feedback for Nonlinear MEM Resonators in Oscillator Circuits

In this paper, a phase feedback approach for using nonlinear microelectromechanical (MEM) resonators in oscillator circuits is investigated. Phase feedback makes use of the oscillation phase condition for oscillator circuits and enables fine-tuning of the frequency at which the resonator oscillates by means of setting the phase in the feedback amplifier. The principle of the approach is illustrated for a nonlinear Duffing resonator, which is representative of many types of MEM resonators. Next, the approach is applied to an electrostatically actuated nonlinear clamped-clamped beam MEM resonator, on simulation level. Phase feedback allows for operation of the resonator in its nonlinear regime. The closed-loop technique enables control of both the frequency of oscillation and the output power of the signal. Additionally, optimal operation points for oscillator circuits incorporating a nonlinear resonator can be defined. Application of phase feedback results in more robustness with respect to dynamic pull in than in open-loop case, however, at the cost of a deteriorated phase noise response.

CMOS implementation of a 1.6 GHz low voltage low phase noise quadrature output frequency synthesizer with automatic amplitude control

This article presents the design of a 1.2 V CMOS low phase noise quadrature output frequency synthesizer (FS) to be used for a GPS tuner application. Special reference is made to the design of a wide tuning range quadrature output voltage-controlled oscillator which is equipped with an automatic amplitude controller. It exhibits a phase noise response of less than ?115 dBc/Hz at an offset of 1 MHz from the carrier and has a tuning range of over 36%. The effect of the automatic amplitude control is shown to improve phase noise at high oscillation frequencies and its noise has a negligible effect on the phase noise response even at low offset frequencies from the carrier. Preliminary analysis is presented showing the negligible effect of a DC---DC converter on the spurious level of the FS, included to permit the use of low sensitivity varactors. Design guidelines for reducing both the loop noise and the AM-to-PM conversion factors of the oscillator are also given. The design was made using the STMicroelectronics 0.13 μm HCMOS9-RF technology design kit.

Predicting random jitter - Exploring the current simulation techniques for predicting the noise in oscillator, clock, and timing circuits

The random jitter performance of clock, oscillator, and timing circuits can be predicted by using steady-state circuit simulation techniques that determine phase noise by analyzing the impact on phase due to thermal, flicker, channel, and shot noise present in the electronic devices. Given the phase noise response, and the steady-state operating conditions of the circuit, a wide variety of jitter measurements can be computed. Each involves a transformation of the phase noise results, with accuracy hinging on the quality of the phase noise response over a suitable range of offset frequencies

A Stydy on Clock-Signal Extraction of a 40-Gbit/s Optical RZ Signal Using an Injection Locking Circuit

Clock signal extrtaction from 40-Gbit/s signals based on injection loocking is demonstrated. The loop frequency is 20 GHz, which enables efficient frequency down conversion and system cost down. Basic characteristics of locking range, phase noise, and frequency response of the system are clarified. The system is applied to the 40-Gbit/s 400-km transmision experiment where error free operation is confirmed for 76 hours.

Effect of nonuniform laser FM response on the performance of multichannel heterodyne FSK systems using optical amplifiers

A theoretical analysis is provided to evaluate the performance of optical frequency division multiplexed systems taking into considerations the combined effect of receiver noise, laser phase noise and nonuniform FM response characteristic of a practical DFB laser. To overcome the effect of nonuniform frequency modulation characteristic of semiconductor lasers, two different linecoding schemes are used for the laser driving signal. The crosstalk penalty due to the combined effect of nonuniform FM response and phase noise of lasers is evaluated. The improvement in receiver sensitivity due to optical preamplifier is also estimated. The computed results show that the performance of the system is highly degraded due to the effect of laser nonuniform fm response and can be reduced substantially by using linecoding. Further, there is considerable improvement in receiver sensitivity due to the use of an optical preamplifier in the absence of phase noise. In the presence of phase noise there is a reduction in receiver sensitivity.

Performance of linecoded optical heterodyne FSK systems with nonuniform laser FM response

A simple theoretical analysis for evaluating the performance of linecoded optical frequency shift keying (FSK) systems is presented. It accounts for the combined effects of laser phase noise, receiver noise, and nonuniform BM response of distributed feedback lasers. A close form expression for the random frequency noise due to the combined effect of laser nonuniform FM response and phase noise is developed. The analysis is carried out for three different linecoding schemes, i.e., alternate mark inversion, Miller code or delay modulation, and Manchester coding, to investigate the efficacy of the line coding schemes in counteracting the effect of nonflat FM response. Theoretical and simulation results show that the sensitivities of linecoded FSK systems are within 0.7 and 0.4 dB for single-branch and dual-branch detection, respectively, at a bit error probability of 10/sup -9/ relative to the random non-return to zero FSK with flat FM response.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effect of line coding on heterodyne FSK optical systems with nonuniform laser FM response

A simple analytical approach for evaluating the system performance due to the combined effects of receiver noise, laser phase noise and laser nonuniform FM response in wide-deviation heterodyne optical FSK system with envelope detection is presented. With this approach, the relative effectiveness of several linecoding schemes, namely alternate mark inversion (AMI), Manchester coding (MC) and delay modulation (DM), in counteracting the pattern-dependent performance degradation due to nonflat FM response has been quantitatively assessed. Theoretical results and simulations show that performance of linecoded systems are within 0.7 dB at bit error probability of 10-9 from the random NRZ-FSK system with flat FM response.

Phase noise characterization of SAW oscillators based on a Newton minimization procedure

An iterative minimization technique is used to optimize the values of circuit and device parameters which determine the phase noise response of a voltage-controlled SAW-stabilized oscillator (VCSO). An expression-developed by T.E. Parker (1985) is used to calculate the double-sideband phase noise to carrier ratio from circuit parameter values; good agreement between calculations and phase noise measurements is achieved by minimizing the squared error through the use of a steepest-descent/Newton-Raphson minimization scheme. Less accurately known circuit parameters are thus optimized in an iterative fashion. Exact expressions for the elements of the Hessian Matrix are used in the Newton-Raphson procedure, allowing for fast computations. The numerical findings suggest that useful results can be obtained in the determination of VCSO circuit parameters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>