High Phase Noise Research Articles

Study of the Bias of the Initial Phase Estimation of a Sinewave of Known Frequency in the Presence of Phase Noise.

The estimation of the parameters of a sinusoidal signal is of paramount importance in various applications in the fields of sensors, signal processing, parameter estimation, and device characterization, among others. The presence, in the measurement system, of non-ideal phenomena such as additive noise in the signals, phase noise in the stimulus generation, jitter in the sampling system, frequency error in the experimental setup, among others, leads to increased uncertainty and bias in the estimated quantities obtained by least squares methods and those derived from them. Therefore, from a metrological point of view, it is important to be able to theoretically predict and quantify those uncertainties in order to properly design the measurement system and its parameters, such as the number of samples to acquire or the stimulus signal amplitude to use to minimize the uncertainty in the estimated values. Previous works have shown that the presence of these non-ideal phenomena leads to increased uncertainty and bias in the estimation of the sinewave amplitude. The present work complements this knowledge by focusing specifically on the effect of phase noise and sampling jitter in the bias of the initial phase estimation of a sinusoidal signal of known frequency (three‑parameter sine fitting procedure). A theoretical derivation of the bias of initial phase estimation that takes into consideration the presence of phase noise in the sinewave is presented. Since a Taylor series approximation was used where only the first term was retained, it was necessary to validate the analytical derivations with numerical simulations using a Monte Carlo type of procedure. This process was applied to different conditions regarding the phase noise standard deviation, initial phase value, and number of samples. It is concluded that, in most scenarios, initial phase estimation using sine fitting is unbiased in the presence of phase noise or jitter. It is shown, however, that in cases of extremely high phase noise standard deviation and a very low number of samples, a bias occurs.

Improved Least Squares Phase Unwrapping Method Based on Chebyshev Filter

Phase unwrapping of high phase noise and steep phase gradient has always been a challenging problem in interferometric synthetic aperture radar (InSAR), in which case the least squares (LS) phase unwrapping method often suffers from significant unwrapping errors. Therefore, this paper proposes an improved LS phase unwrapping method based on the Chebyshev filter, which solves the problem of incomplete unwrapping and errors under high phase noise and steep phase gradient. Firstly, the steep gradient phase is transformed into multiple flat gradient phases using the Chebyshev filter. Then the flat gradient phases are unwrapped using the LS unwrapping method. Finally, the final unwrapped phase is obtained by iteratively adding the unwrapping results of the flat gradient phases. The simulation results show that the proposed method has the best accuracy and stability compared to LS, PCUA, and RPUA. In the real InSAR phase unwrapping experiment, the RMSE of the proposed method is reduced by 63.91%, 35.38%, and 54.39% compared to LS, PCUA, and RPUA. The phase unwrapping time is reduced by 62.86% and 11.64% compared to PCUA and RPUA.

Dissipative Kerr soliton generation at 2μm in a silicon nitride microresonator

Chip-scale optical frequency combs enable the generation of highly-coherent pulsed light at gigahertz-level repetition rates, with potential technological impact ranging from telecommunications to sensing and spectroscopy. In combination with techniques such as dual-comb spectroscopy, their utilization would be particularly beneficial for sensing of molecular species in the mid-infrared spectrum, in an integrated fashion. However, few demonstrations of direct microcomb generation within this spectral region have been showcased so far. In this work, we report the generation of Kerr soliton microcombs in silicon nitride integrated photonics. Leveraging a high-Q silicon nitride microresonator, our device achieves soliton generation under milliwatt-level pumping at 1.97 µm, with a generated spectrum encompassing a 422 nm bandwidth and extending up to 2.25 µm. The use of a dual pumping scheme allows reliable access to several comb states, including primary combs, modulation instability combs, as well as multi- and single-soliton states, the latter exhibiting high stability and low phase noise. Our work extends the domain of silicon nitride based Kerr microcombs towards the mid-infrared using accessible factory-grade technology and lays the foundations for the realization of fully integrated mid-infrared comb sources.

Theoretical Demonstration of Improved Performance in Multi-Channel Photonic RF Signals Based on Optical Injection Locking of Optical Comb and Array Lasers

Multi-channel radio frequency (RF) signal generation, facilitated by photonic technology, offers significant potential for generating coherent signals with a high frequency and low phase noise, providing multifunctional capabilities across diverse platforms, including RF and photonic systems. Traditional methods for multi-channel photonic RF signal generation typically entail the integration of diverse optical components, such as filters and amplifiers. However, this integration often results in compromises related to power efficiency, cost-effectiveness, and implementation simplicity. To address these challenges, we propose a novel method for generating multi-channel photonic RF signals based on optical injection locking technology. This approach eliminates the necessity for traditional optical components, leading to a substantial enhancement in the performance of photonic RF signals. We present the design of an optical injection locking-based multi-channel photonic RF signal generation schematic and theoretically evaluate its Signal-to-Noise Ratio (SNR) and eye pattern performance for data modulation using the Lumerical INTERCONNECT simulator. Our results reveal a significant 1.3-dB and 3.6-dB enhancement in SNR for 30-GHz and 60-GHz signals, respectively. Furthermore, we observed an improved communication performance, as evidenced by enhanced eye patterns in 3-Gbps data transmission compared to passive photonic RF signal generation methods.

Application of Machine Vision Technology in Defect Detection of High Performance Phase Noise Measurement Chips

Application of Machine Vision Technology in Defect Detection of High Performance Phase Noise Measurement Chips

A High FoM and Low Phase Noise Edge-Injection-Based Ring Oscillator in 350 nm CMOS for Sub-GHz ADPLL Applications

This paper presents an injection locked digitally controlled ring oscillator (IL-DCRO). To reduce jitter variations, minimize oscillator spurious signals, and eliminate periodical phase error, a double edge-injection (window injection) scheme with synchronized edge directions is proposed. A combinational edge generator is utilized to substitute the sequential edge generators for injection timing requirements relaxation. By biasing devices in deep triode, digitally controlled delay cells currents are adopted for frequency tuning. This helps reducing the devices flicker (1/f) noise and minimize the DCRO overall phase noise. At 1 MHz offset of frequency, the proposed oscillator has a measured phase noise of −125.95 dBc/Hz and −115.6 dBc/Hz at oscillation frequencies of 913.4 MHz and 432.6 MHz, respectively. Fabricated in 350 nm CMOS process, with a maximum power consumption of 3.3 mW, and oscillating at 913.4 MHz, this DCRO achieves a tuned oscillator figure of merit (FoM) of −197.35 dBc/Hz. The core area of this edge-injection-based DRCO is only 0.08 mm2.

3D integration enables ultralow-noise isolator-free lasers in silicon photonics

Photonic integrated circuits are widely used in applications such as telecommunications and data-centre interconnects1–5. However, in optical systems such as microwave synthesizers6, optical gyroscopes7 and atomic clocks8, photonic integrated circuits are still considered inferior solutions despite their advantages in size, weight, power consumption and cost. Such high-precision and highly coherent applications favour ultralow-noise laser sources to be integrated with other photonic components in a compact and robustly aligned format—that is, on a single chip—for photonic integrated circuits to replace bulk optics and fibres. There are two major issues preventing the realization of such envisioned photonic integrated circuits: the high phase noise of semiconductor lasers and the difficulty of integrating optical isolators directly on-chip. Here we challenge this convention by leveraging three-dimensional integration that results in ultralow-noise lasers with isolator-free operation for silicon photonics. Through multiple monolithic and heterogeneous processing sequences, direct on-chip integration of III–V gain medium and ultralow-loss silicon nitride waveguides with optical loss around 0.5 decibels per metre are demonstrated. Consequently, the demonstrated photonic integrated circuit enters a regime that gives rise to ultralow-noise lasers and microwave synthesizers without the need for optical isolators, owing to the ultrahigh-quality-factor cavity. Such photonic integrated circuits also offer superior scalability for complex functionalities and volume production, as well as improved stability and reliability over time. The three-dimensional integration on ultralow-loss photonic integrated circuits thus marks a critical step towards complex systems and networks on silicon.

Power-frequency performance of step-graded double Gunn diodes

Simulations of conventional Gunn diodes containing the double Gunn effect have shown a significant increase in oscillation frequency and frequency range. However, conventional Gunn diodes suffer from higher phase noise, lower efficiency, and reduced temperature stability due to the lack of a hot electron injector. A study on the performance of a Double Gunn diode with a graded gap injector is presented. The second region of negative differential mobility is gradually introduced in several temperature-dependent mobility models, which are implemented in an energy balance simulation. Devices with transit lengths of 0.7μm, 1.1μm, and 1.65μm are simulated. All devices experience an increase in oscillation frequency with increasing intensities of the double Gunn effect. The frequency range doubles at significant intensities of the effect in the devices with transit lengths of 0.7μm and 1.65μm.

Анализ и разработка высокоточного генератора частоты w-диапазона с низким уровнем паразитных гармоник

For millimeter waves applications in the W-band 93.5-95.5 GHz, improved frequency synthesizers are highly demanded. Improved frequency synthesizer should be tunable synthesizer with high step resolution and possess high phase noise performance, low spurious harmonic levels and short locking time. These parameters are conflicting parameters in developing a high precision frequency oscillator with a pure spectrum. Therefore, it's necessary to make a compromisation between them. In this paper we present a frequency synthesizer based on a Gunn diode, two stable finely tuned frequency sources, a phase locked loop, and a 10th order subharmonic mixer in the feedback loop is built. The phase noise, spurious levels, and tuning step size of the phase locked loop generator are then analyzed, and the effect of each parameter on the others is introduced. To test the performance of the proposed frequency synthesizer using a spectrum analyzer, the output spectrum of the intermediate frequency was measured on a subharmonic mixer, which corresponds to the spectrum of a phase-locked loop generator. The results show that the proposed phase-locked loop generator can be tuned in steps of less than 1 Hz, and the first two spurious harmonics are far from the fundamental harmonic. These results can be used for designing an enhanced high precision frequency synthesizer with a low level of spurious harmonics and high phase noise performance in millimeter waves applications such as CW RADAR.

0.18-μm CMOS process 40 MHz–4.41 GHz frequency synthesizer with high linearity low phase noise varactor-reconstruction LC-VCO

A 40 MHz–4.41 GHz fractional-N frequency synthesizer (FS) with varactor-reconstruction VCO (VRVCO) fabricated in the standard 0.18-μm CMOS process is demonstrated. In the conventional VCO, owing to non-linearity of varactor and parasitic effects of switched-MOSFET, the top and bottom of the tuning curves show nonlinearity. The novel design of VRVCO for tuning sensitivity base on series-shunt hybrid capacitor-varactor part and optimized switched-capacitor bank is incorporated into the 4.41 GHz FS design to reduce the variation of the VCO gain, realize high linearity tuning curves and improve phase noise performance. Furthermore, a noise reduction topology is adopted to decrease phase noise of VRVCO. Simulated results show the proposed VRVCO can improve linearity of tuning frequency over the entire tuning range. The measured results show the overall tuning range exceeds 115% from 1.92 to 4.41 GHz including three VRVCOs with high linearity (fine-tuning sensitivity: 131%, coarse-tuning sensitivity: 106%) and the phase noise is −120dBc/Hz at 1 MHz offset from the carrier frequency of 4.41 GHz.

Frequency-Modulated OFDM: A New Waveform for High-Mobility Wireless Communications

This paper introduces a novel waveform for wireless communication, denoted as Frequency-Modulated Orthogonal Frequency-Division Multiplexing (FM-OFDM). By frequency-modulating an OFDM signal and further defining a suitable cutoff subcarrier, the resulting constant-envelope waveform (ensuring a low Peak to Average Power Ratio) exhibits strong robustness not only to Doppler, but also to phase noise and carrier frequency offsets. These impairments introduce an additive error term at the information-bearing subcarriers that is mostly concentrated at the lowest part of the spectrum. No inter-carrier interference is thus present, and impairments can be easily overcome by mapping the information above a cutoff subcarrier. Theoretical expressions and numerical results prove the superiority of FM-OFDM over the state of the art, particularly in high-speed Rayleigh channels and/or high phase noise.

A Fractional-N CP-PLL with fast two-point modulation calibration using duty-cycle and polarity tracking technique in 110-nm CMOS

This article proposes a fractional-N charge pump phase-locked loop (CP-PLL) with fast two-point modulation calibration using Duty-Cycle and Polarity Tracking technique. The proposed calibration method can perform delay and gain calibration within 15 μs, respectively. A DTC-assisted Polarity Detector is used to track and countervail the propagation delay of two modulation paths. A TDC-based Duty-Cycle Detector is used to monitor and compensate the two paths gain mismatch. By comparing the code with the threshold set in the look-up table (LUT), a quick calibration can be achieved. To maintain high out-band phase noise performance and stronger robustness, a Class-C oscillator using Capacitance Desensitization technique and Cross-Bias technique is adopted in the design. The proposed CP-PLL is implemented in a standard 110-nm CMOS technology, occupying 2.7 mm2 silicon area. The post-simulation results show the proposed calibration method can calibrate the delay/gain mismatch within 30 μs. Fast calibration mode supports calibration time within 62.5 ns. The phase noise performance is −91-dBc/Hz@100 kHz, −119-dBc/Hz@1 MHz. The entire CP-PLL dissipates 20.9-mW and achieves an RMS jitter of 6.2 ps, corresponding to a figure of merit (FOM) of −211-dB.

Optical phase-locked loop phase noise in 5G mm-wave OFDM ARoF systems

The use of millimeter-wave (mm-wave) frequencies is required in order to support the increasing number of connected devices expected from the fifth generation (5G) of mobile communications. Subsequently, the generation of radio-frequency (RF) carriers ranging from 10GHz to 300GHz and their transport through optical distribution network (ODN) is a key element of the future 5G fronthaul. Optically assisted RF carrier generation is one of the most promising solutions to tackle this issue, allowing a wide use of analog radio-over-fiber (ARoF) architectures. However the main limitation of these optical methods is related to the finite coherence of lasers sources, which can dramatically degrade data transmission in analog formats. To mitigate its impact, the use of orthogonal frequency-division multiplexing (OFDM) as the 5G standard allows employing efficient phase noise compensation algorithms. Therefore, in this study, we present an experimental demonstration of a mm-wave generation technique based on an optical phase-locked loop (OPLL) that fulfills the frequency specifications for 5G. Then, an algorithm is introduced that improves data recovery at reception and reduces the impact of a possible high phase noise carrier. Finally, a back-to-back data transmission experiment is performed, demonstrating the efficiency of the algorithm to reach the 5G requirements. These results emphasize the use of OPLLs as a viable solution to generate mm-wave carriers for 5G and beyond.

An All-Optical Ka-Band Microwave Long-Distance Dissemination System Based on an Optoelectronic Oscillator

We proposed an all-optical Ka-band microwave long-distance dissemination system based on an optoelectronic oscillator (OEO). In this system, a single tone with high spectrum purity and low phase noise is excited by an injection-locked OEO, and distributed to the remote site through the fiber loop of the OEO at the same time. The second harmonic of the reference signal modulates the round-tripping optical signal at the local site, which achieves the phase conjugator at the optical domain. At the remote end, the phase-conjugated signal is photomixed with the OEO signal to eliminated the phase offset. The proposed scheme improves the phase noise of the high frequency signal received at the remote site and reduces the photoelectric conversion loss. We demonstrated the transmissions of a 36 GHz frequency-quadrupled RF signal along a 6 km optical fiber loop, and the frequency stability is 1.069 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−14</sup> /1 s and 3.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−16</sup> /1000 s. The single-sideband (SSB) phase noise of the received signal at the remote site is up to −130 dBc/Hz at 10 kHz offset frequency.

Injection-locked optoelectronic oscillator with high side-mode suppression ratio and low phase noise based on frequency-conversion delay matching

An injection-locked optoelectronic oscillator (OEO) based on frequency-conversion delay matching is proposed and experimentally demonstrated. There are two branches in the proposed OEO, where one branch is used to maintain the oscillation in the cavity, and the other one based on frequency conversion is used to generate a pure frequency-converted injection signal. Owing to the frequency-conversion-based injection locking effect, the side-mode suppression ratio of the proposed OEO can be greatly improved. In addition, the phase noise deterioration induced by the externally-injected signal can be effectively eliminated when the time delays of the two branches are well matched. In the experiment, a pure single-tone microwave signal at 9.99998 GHz is generated, whose side-mode suppression ratio and phase noise are measured to be 74.4 dB and −130 dBc/Hz@10 kHz, respectively.

A High Speed Phase Detection Circuit with No Dead Zone Suitable for Minimal Jitter and Low Power Applications

A novel phase frequency detector design is introduced in this study, which removes dead and blind zone issues by eliminating reset path, therefore accelerating the acquisition process. High speed, low power and minimal phase noise are all characteristics of the proposed circuit. The circuit is designed in the Cadence Virtuoso environment and is implemented in CMOS GPDK 180 nm library using a 1.8 V supply voltage. Post-layout simulations have been conducted to ensure that the findings are accurate. The circuit’s robustness is tested over process, voltage and temperature fluctuations. The suggested PFD achieves a phase noise of [Formula: see text][Formula: see text]dBc/Hz, which is significantly lower than other published circuits. This PFD dissipates 10.25[Formula: see text][Formula: see text]W of power at its maximum operating frequency of 10 GHz. The PFD encompasses an area of 275[Formula: see text][Formula: see text]m2. The proposed PFD outperforms other PFD circuits in the literature, making it ideal for applications requiring minimal jitter, low power, etc.

Ultra low phase noise and high output power monolithic microwave integrated circuit oscillator for 5G applications

novel structure of low phase noise and high output power monolithic microwave integrated circuit (MMIC) oscillator is presented in order to use it in 5G applications. The oscillator is based on the ED02AH process which allows us to design a microwave oscillator keeping a minimum size which is impossible to have it using other technologies since microwave oscillators are sensitive components above 20 GHz. The oscillator is studied, designed, and optimized on a GaAs substrate from the OMMIC foundry using the advanced design system (ADS) simulator in order to obtain a miniaturized oscillator (1.1×1.3 mm&lt;sup&gt;2&lt;/sup&gt;) generating two signals of different frequencies f&lt;sub&gt;o1&lt;/sub&gt;=26 GHz and f&lt;sub&gt;o2&lt;/sub&gt;=30 GHz. The objective is to design an oscillator with high output power and low phase noise while respecting its specifications. The optimization of the proposed microwave oscillator shows satisfying results. Indeed, at 26 GHz and 30 GHz, the output powers are respectively 13.33 dBm and 14.89 dBm. The oscillator produces a sinusoidal signal of 1.5 V and 1.75 V amplitude respectively at 26 GHz and 30 GHz. The oscillator phase noise at f&lt;sub&gt;o1&lt;/sub&gt; and f&lt;sub&gt;o2&lt;/sub&gt; resonance frequencies using the liquid crystal (LC) resonator shows respectively -109 dBc/Hz and -110 dBc/Hz at 10 MHz offset.

A 40 GHz CMOS PLL With −75-dBc Reference Spur and 121.9-fsrms Jitter Featuring a Quadrature Sampling Phase-Frequency Detector

The high phase noise (PN) of CMOS millimeter-wave oscillators has encouraged the adoption of wide loop bandwidth for an integer- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> phase-locked loop (PLL). This article proposes a quadrature sampling phase-frequency detector (QS-PFD) to disengage the tradeoff between spur rejection and loop bandwidth. With the introduction of an auxiliary path for phase detection, the spur generated by the main path is canceled without incurring extra power or degrading the loop stability. The high gain of the QS-PFD attenuates its jitter contribution to the loop. The QS-PFD enables fast frequency detection and lock detection. Implemented in 40-nm CMOS technology, the proposed PLL shows a −75-dBc reference spur, −101.5-dBc/Hz PN at a 1-MHz offset, and a minimum integrated jitter of 121.9 fs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> (10 kHz–100 MHz) at 38.2 GHz with a division ratio of 128. The lock detection time is at the microsecond level. The proposed PLL consumes 23.6 mW from a 1.1-V power supply, leading to a figure of merit (FoM) of −245 dB.

Simultaneous RF Self-Interference Cancellation, Local Oscillator Generation, Frequency up- and down-Conversion in an Integrated In-Band Full-Duplex 5G RF Transceiver Front-End

Wideband radio-frequency (RF) self-interference cancellation (SIC), local oscillator (LO) generation, frequency up-, and down-conversion are all crucial for an in-band full-duplex (IBFD) 5G RF transceiver front-end. In this paper, a microwave photonic approach enabled by only one optical dual-polarization IQ modulator (DP-IQMZM) is proposed to simultaneously realize wideband RF SIC, LO generation, frequency up- and down-conversion. Note that, the LO signal with high spectral purity and low phase noise is produced by a dual-loop optoelectronic oscillator (OEO) using a self-polarization stabilization structure, and the generated LO signal is applied for frequency up- and down-conversion. Besides, the optical single-sideband signal is produced at the output of this 5G RF transceiver for uplink transmission from the remote antenna unit (RAU) to the baseband unit (BBU), so the power fading induced by fiber dispersion could be completely suppressed. A proof-of-concept experiment is performed, and the LO signal with the central frequency of 10&#x00A0;GHz, the phase noise performance of &#x2212;108.97&#x00A0;dBc&#x002F;Hz at a frequency offset of 10&#x00A0;kHz is achieved. A 5 &#x00D7; 20&#x00A0;MHz Long Term Evolution (LTE) 16&#x002F;64-ary quadrature amplitude modulation-orthogonal frequency division multiplexing (16&#x002F;64QAM-OFDM) signal with the central frequency of 12.6&#x00A0;GHz is down-converted to 2.6&#x00A0;GHz. Meanwhile, the cancellation ratio of 30.22&#x00A0;dB and 26.26&#x00A0;dB could be achieved when the bandwidth of the self-interference signal is 150&#x00A0;MHz and 300&#x00A0;MHz, respectively. Moreover, a 3 &#x00D7; 20&#x00A0;MHz LTE 64QAM-OFDM signal with a central frequency of 2.6&#x00A0;GHz is up-converted to 12.6&#x00A0;GHz, and the electrical signal-to-noise ratio of the generated RF signal can achieve 31.34&#x00A0;dB. The measured error vector magnitude performance shows that the generated down- and up-converted signal both meet the 3^rd Generation Partnership Project (3GPP) requirements for 5G systems.

An opto‐electronic oscillator based on Fabry‐Perot stabilized dual‐wavelength fiber ring laser

AbstractThe authors experimentally demonstrate an opto‐electronic oscillator based on a dual‐wavelength fiber ring laser with an inline specially designed fiber‐Bragg‐grating‐based Fabry‐Perot filter. An erbium‐doped fiber amplifier initiates the process as a broadband light source while a second optical amplifier provides additional gain to increase the cavity power. By exploiting the two‐wavelength beating, a 10.3 GHz microwave carrier with 3‐dB linewidth of &lt;200 Hz was generated with 77 dB signal‐to‐noise ratio. Phase noise of −100 dBc/Hz @10 kHz offset is achieved, which is very appropriate for microwave applications in X‐band that often require high extinction ratio and low phase noise.