Search

This paper investigates the effect of oscillator phase noise on a multiuser millimeter wave (mmWave) massive MIMO uplink as we scale up the number of base station antennas, fixing the load factor, defined as the ratio of the number of simultaneous users to the number of base station antennas. We consider a modular approach in which the base station employs an array of subarrays, or "tiles." Each tile supports a fixed number of antennas, and can therefore be implemented using a separate radio frequency integrated circuit (RFIC), with synchronization across tiles accomplished by employing a phased locked loop in each tile to synthesize an on-chip oscillator at the carrier frequency by locking on to a common lower frequency reference clock. Assuming linear minimum mean squared error (LMMSE) multiuser detection, we provide an analytical framework that can be used to specify the required power spectral density (PSD) mask for phase noise for a target system performance. Our analysis for the phase noise at the output of the LMMSE receiver indicates two distinct effects: self-noise for each user which is inversely proportional to the number of tiles, and cross-talk between users which is insensitive to the number of tiles, and is proportional to the load factor. These analytical predictions, verified by simulations for a 140 GHz system targeting a per-user data rate of 10 Gbps, show that tiling is a robust approach for scaling. Numerical results for our proposed design approach yield relatively relaxed specifications for phase noise PSD masks.

Cell-free massive multiple-input multiple-output (MIMO) is considered as a promising technology for satisfying higher rate requirement of users in beyond-5G networks. This paper investigates the impact of phase noise on the performance of cell-free MIMO systems which employ a large number of multi-antenna access points (APs). For both downlink and uplink transmissions, we derive the tractable closed-form achievable rate expressions when signal detection with channel state information (CSI) and channel distribution information (CDI), respectively, by utilizing the extended deterministic equivalence method in random matrix theory. The closed-form achievable rate expressions provide efficient evaluation for the impact of phase noise on system performance. The analytical results indicate that the phase noise influences the power of the desired signal, the beamforming uncertainty gain, and the inter-user interference increment caused by the pilot contamination. In addition, the special cases that only APs have phase noise and only users have phase noise are discussed. It is found that the impact of phase noise at users is more severe than that at APs. Besides, we discuss the system performance at low and high SNR regimes. It demonstrates that the phase noise is the major limitation of the system performance in high SNR regime while it can be neglected in low SNR regime. Furthermore, we formulate the max-min power control problem for both downlink and uplink transmissions to guarantee the users’ fairness and prove that the downlink max-min problem is a quasi-concave problem while the uplink max-min problem is a geometric programming (GP) problem. Then, the phase noise-aware max-min power control schemes for both downlink and uplink transmissions are proposed to ensure the users’ fairness. Finally, numerical results are provided to validate the analytical results and the proposed phase noise-aware power control scheme.

The oscillator phase noise is one of the key limitations in several fields of electronics. An electronic oscillator phase noise is usually described by the Leeson's equation. Since the latter is frequently misinterpreted and misused, a complete derivation of the Leeson's equation in modern form is given first. Second, effects of flicker noise and active-device bias are accounted for. Next the complete spectrum of an electronic oscillator is derived extending the result of the Leeson's equation into a Lorentzian spectral line. Finally the spectrum of more complex oscillators including delay lines is calculated, like opto-electronic oscillators.

In this work, the effect of oscillator phase noise on the bit error rate (BER) for high order QAM communication systems is analyzed. Two high frequency oscillators are designed, built and tested to get real phase noise data, and a BER simulation of a 1024 QAM signal through a super-heterodyne frequency down-converter is implemented using the measured data from the two oscillators as local oscillator sources for the down-converter. A third frequency source is also added to the simulation to visualize the dramatic effect of phase noise on the system BER analysis.

In this paper we investigate the direct effect of resonator quality factor ( $Q$ ) on the oscillator phase noise. We use 2-port contour mode resonators (CMRs), fabricated both with aluminum nitride (AlN) and aluminum scandium nitride (AlScN), as the frequency-determining element in the oscillator circuit. Over 70 oscillator configurations are tested using resonators with different $Q$ and with different piezoelectric layer. The testing of so many devices is possible because, in our setup, interfacing the circuit to the resonator is streamlined using RF probes. Our results show that higher resonator $Q$ yields better frequency stability of the oscillator, for both AlN and AlScN CMRs. Interestingly, the comparison between AlN-based oscillators and AlScN-based oscillators with equal $Q$ shows that AlScN-based oscillators’ Phase Noise is up 10 dBc/Hz better than the AlN oscillator at 1 kHz offset frequency, suggesting different intrinsic resonator flicker noise of the two piezoelectric layers. [2019-0200]

To meet the requirements of beyond 5G networks, the significant amount of unused spectrum in sub-TeraHertz frequencies is contemplated for high-rate wireless communications. Yet, the performance of sub-TeraHertz systems is severely degraded by strong oscillator phase noise. We investigate in this paper the design of digital communications robust to phase noise. This problem is addressed in three steps: the characterization of the phase noise channel, the design of the optimum receiver, and the optimization of the modulation scheme. This paper proposes a joint performance and implementation optimization. First, we address the design of the demodulation scheme for phase noise channels and propose the polar metric, a soft-decision rule for symbol detection. It is shown that performance gains are achieved for coded and uncoded systems with valuable complexity reductions of the receiver. Second, we investigate the optimization of the modulation scheme for phase noise. We demonstrate that using a constellation defined upon a lattice in the amplitude-phase domain leads to significant performance gains and a low-complexity implementation. Thereupon, we propose the Polar-QAM scheme with efficient binary labeling and demodulation. Numerical simulation results show that the proposed modulation and demodulation schemes offer valuable solutions to achieve high-rate communications on systems strongly impaired by phase noise.

We present analytic expressions for the clock phase error power spectral density (PSD) resulting from a previously reported decentralized distributed wireless synchronization protocol acting on independent sensor oscillators. We provide an overview of oscillator phase noise error modelling and examine the effects of the wireless synchronization protocol and the resulting synchronized clock phase noise PSDs. We present results from both simulation and experiment to validate the expressions derived.

International audience; This paper presents a high-resolution Class-C type voltage-controlled oscillator (VCO) with a robust startup. The proposed oscillator achieves a minimum frequency quantification step of 270 Hz without adding any additional dithering approach. The very fine tuning is obtained through a capacitive-inductive degeneration coupling (CIDC) technique which reduces the capacitance value without appreciably affecting the intrinsic oscillator phase noise (PN). This technique also provides a negative transconductance to compensate for losses in the LC tank, resulting in high oscillation amplitude and relatively low power consumption in the oscillator core. The proposed design, implemented in 130 nm CMOS technology, achieves 45% tuning range. It exhibits a phase noise of-107 dBc/Hz @ 1-MHz offset, while it draws 5.75 mA from a supply of 1.2 V, resulting in a FoM of 165 dBc/Hz.

Software-defined radio transceivers, wireless infrastructure equipment, and test equipment require the local oscillator (LO) to cover a very wide range of the output frequencies while meet the phase noise performance. The most straightforward method for a wide tuning range is to adopt multiple separated oscillators. However, this method suffers from the bulky area and relatively complicated multiplexing functions. The authors in [1] introduces triple-coupled inductors that create multiple resonant frequency in a high-order resonator. Nevertheless, the impedance magnitude looking into either port of the high-order resonator shows higher peak value at the lower resonant frequency, which makes it difficult to sustain stable oscillation at higher resonant frequency when the coupling factor is large. The VCO in [2] exploits series 8-shaped coils to generate two oscillation modes without coupling between each other while occupying compact area. However, the quality factor of the 8-shaped inductor is considerably lower than a typical octagonal inductor thereby degrading the oscillator phase noise. In order to solve the above-mentioned issues, a dual-core quad-mode orthogonal-coupled VCO using parallel 8-shaped resonator is proposed. Each core in the proposed VCO have two modes, with one mode being equivalent to the 8-shaped inductor, which allows both cores to be orthogonal to each other by proper configurations.

Frequency delta sigma modulation (FDSM) is a unique analog to digital conversion technique featuring large dynamic range with wide frequency band width. It can be used for high performance digitaloutput sensors, if the oscillator in the FDSM is replaced by a variable frequency oscillator whose frequency depends on a certain external physical quantity. One of the most important parameters governing the performance of these sensors is a phase noise of the oscillator. The phase noise is an essential error source in the FDSM, and it is quite important for this type of sensors because they use a high frequency oscillator and an extremely large oversampling ratio. In this paper, we will discuss the quantitative effects of the phase noise on the FDSM output on the basis of a simple model. The model was validated with experiments for three types of oscillators. key words: delta sigma modulation, frequency delta sigma modulation, phase noise, microwave oscillator, Advance publication (published online immediately after acceptance)

This paper presents an in-depth analysis of effect of oscillator phase noise (PN) on the performance of orthogonal frequency division multiplexing (OFDM) systems in sub-terahertz (Sub-THz) band. We use the empirical PN measurement of current Sub-THz signal sources to propose a two-part PN model that captures the unique characteristics of PN in Sub-THz band. Subsequently, the proposed model is used to analyze the performance of OFDM systems affected by PN. Our analysis reveals some key distinctions between the effect of PN on the OFDM systems operating at Sub-THz and the same systems operating at conventional microwave frequency bands. In particular, we show that in these systems: 1) the PN floor has a significant effect on the performance degradation, 2) the assumption of PN being a low-pass process is inaccurate, and 3) the existing OFDM PN mitigation schemes are less effective. To verify our analysis the upper bound on the signal-to-interference-and-noise ratio (SINR) after using the existing PN mitigation schemes under limited computational complexity constraint is derived and the effect of PN floor on the SINR is analytically calculated.

The oscillator phase noise (PN) is one of the bottlenecks toward increasing the modulation order in the OFDM-based wireless backhaul links. This paper presents an algorithm to overcome this barrier through a novel time-domain iterative phase noise mitigation method. In the first step, by leveraging the high signal-to-noise ratio of the backhaul links, the PN estimation problem in the OFDM system is formulated similar to the PN estimation in the single carrier system, for which several solutions are proposed in the literature. Subsequently, a decision directed approach is used to solve this estimation problem, which relies on the linear interpolation of refined estimates of the PN. The proposed algorithm secures a significant improvement in the phase noise suppression of the OFDM systems in the high signal-to-noise-ratio regime. By requiring small pilot overhead while avoiding computationally complex operations in the algorithm’s iterations, the proposed method is tailored specially for the OFDM-based wireless backhaul links. Numerical results verify the effectiveness of proposed PN mitigation scheme.

The significant amount of unused spectrum in sub-TeraHertz frequencies is contemplated to realize high rate wireless communications for beyond 5G networks. Yet, the performance of sub-TeraHertz systems is severely degraded by strong oscillator phase noise. Therefore, we investigate in this paper the use of multiple-input multiple-output (MIMO) systems with energy detection receivers to achieve high rate communications robust to phase noise. First, the design of the receiver detection algorithm is addressed. We derive the joint maximum likelihood detector corresponding to the studied nonlinear MIMO channel. Second, the system performance is assessed through numerical simulations. We consider a realistic scenario modeling an indoor wireless link with directive antennas and strongly correlated line-of-sight channels. Our results demonstrate that high rate sub-TeraHertz systems can be implemented on low-complexity and low-power architectures using MIMO systems and energy detection receivers.

In order to design a big system, it is very important to make a reasonable model of an analog circuit, as it is used to explore how the performance of the analog circuit affects the system performance, without running a time-consuming simulation with physical devices or gates. System Verilog is widely used in those fields for highlevel simulations including analog circuit models. In this appendix, an example of System Verilog modeling of CMOS clock generator is provided. Based on the phase noise and jitter sources of a generic clock generator that we studied in Chapter 6, we include the following jitters in the model: (1) the white (random) jitter induced from the white noise of the output buffer stage, (2) the oscillator phase noise, (3) the phase noise of reference clock, and (4) the sinusoidal jitter. Basically, the purpose of the clock jitter model is to get the phase noise profile from a designer and translate it to the actual timing perturbation.

An array of short mechanical couplers scheme to realize a support transducer enabled Wine-glass resonator/oscillator exhibiting a quality factor ( $Q$ ) of 17,000 and an oscillator Phase Noise (PN) meeting the GSM spec. at 1 kHz and 1 MHz offsets has been demonstrated in this work. A 20.3-MHz Wine-glass resonator fabricated using the MEMSCAP platform is used to implement the oscillator. The meticulous structural and material engineering aspect of the resonator improves the quality factor of the design from 9,500 to 17,000, making the resonator an ideal candidate for high-end oscillator applications. An attenuator and phase control methodology along with commercially available amplifiers has been used to realize a low phase noise oscillator with a PN of −134.1 dBc/Hz and −152.3 dBc/Hz at 1 kHz and 1 MHz offsets respectively while divided down to GSM's 13 MHz.

Herein, a robust programmable stochastic weight generation method for a memristive neural network is proposed. There have been few prior algorithm suggestions for crossbar neural network‐based stochastic learning; however, there has not been much attention focussed on robust physical implementations. As a result, coming up with a robust method to provide the probability generator is an essential knob for its physical implementation. Here, implanting such stochastic behavior into the weight update signal itself is proposed, by multiplying it with the randomized probability sequence. To generate such probability sequence, bang‐bang dithering of a phase‐locked loop (PLL) with a binary phase detector (PD) is used. The programmable probability is enabled by introducing an offset for the PD outputs. Yet the dithering sequence has deterministic nature, phase noise of complementary metal–oxide–semiconductor (CMOS) ring oscillator to randomize the deterministic dithering is exploited. As a result, this lower power oscillator offers a better probability sequence, which enables an ultralow power circuit implementation.

International audience; The performance of sub-THz communications, contemplated for the next generation of wireless networks, are significantly degraded by oscillator phase noise. In this paper, we address the design of a single carrier transceiver resilient to phase noise. This problem is treated in two steps: First, we derive for phase noise channels the optimum symbol detection criterion. Second, we propose a phase noise robust modulation scheme with a comprehensive and efficient structure. System level simulations modeling the sub-THz propagation channel of a rich outdoor environment through ray tracing are also presented. Results show that optimizing the modulation and demodulation schemes is necessary to achieve high spectral efficiency in the presence of phase noise.

Synchronous demodulation is a well-established technique for precise definition and reduction of noise bandwidth in various applications. Typically the noise added by the nonlinear elements such as reference oscillator and demodulator is assumed to be negligible. However, with the scaling of the dimensions of micro-sensors, the signals from these sensors generally tend to become weaker. Therefore, there is a need to study the so far neglected noise contributions from the components of the synchronous demodulator. In this paper, we focus on the significance of the phase noise of the reference oscillator on the system performance. A detailed analytical model is developed to investigate the nonlinear interaction. It is shown that the phase noise of the reference oscillator can significantly contribute to the output noise depending on the phase difference between the reference and measured signals. Close-to-resonance phase noise components produce low- frequency components at the output. However, our experimentally tested analysis indicates that the effect of phase noise on the output signal can be eliminated by complete compensation of the phase shift between reference and measured signals. This study applies to the design of low cost, high-performance measurement systems for high precision sensor applications.

Sub-sampling (SS) and injection-locking (IL) techniques are becoming increasingly popular for 5G millimeter-wave (mmW) frequency generation [1], [2] due to their ability to achieve ultra-low jitter (

This paper shows how arrays of coupled resonant oscillators can provide wildly disordered phase responses corresponding to nonsynchronized regimes. The unpredictability of their time response makes oscillator arrays attractive randomness sources for cryptographic applications. We describe a possible implementation of a random number generator (RNG) combining the proposed randomness source with a few low cost elements needed for bit stream generation. Several bit stream sequences are simulated with a numerically efficient phase-domain model able to include oscillator phase noise and parameters variability. The randomness of the generated bit streams are checked with the tests provided by the National Institute of Standards and Technology. Our results show that the statistical properties of the proposed RNG are indeed resilient to temperature-induced thermal noise variations as well as to the statistical uncertainty of oscillating frequencies and coupling strengths.

The maximum oscillation frequency depends on the oscillator topology and the loss of oscillator’s active and passive components. The oscillator phase noise, and hence the oscillator figure-of-merit ( $FOM$ ), degrades much faster than the well-known low-frequency expressions as the oscillation frequency reaches the maximum oscillation frequency. This paper covers the analysis and design of Colpitts oscillators with the best possible phase noise as the oscillation frequency approaches the maximum oscillation frequency while predicting the degradation in $FOM$ . Experimental results corresponding to proof-of-concept differential Colpitts oscillator prototypes at 106 and 148 GHz that use a resonant biasing scheme to reduce phase noise, implemented in a 130-nm SiGe HBT BiCMOS technology, are presented. Ideally, the oscillator phase noise at a given frequency can be reduced by increasing the power consumption, while appropriately scaling the oscillator components. Such power scaling cannot be done indefinitely as it leads to impractical passive component values. Coupling identical oscillators is an alternate approach to enhance the phase noise. In this paper, a common-mode coupling scheme is introduced as a robust technique in reducing phase noise in millimeter wave frequencies. Experimental results of a 106-GHz 8-element common-mode coupled Colpitts oscillator, implemented in a 130-nm SiGe HBT BiCMOS technology, with a measured phase noise of −111 dBc/Hz at 1-MHz offset while consuming 90 mW are presented.

Oscillator phase noise has a negative effect on the tracking performance of Global Navigation Satellite System (GNSS) receivers. To provide GNSS software receivers with real test environments, this paper proposes a method to simulate the GNSS Intermediate Frequency (IF) signal, taking the oscillator phase noise effect into consideration. The oscillator parameters are first measured via a pseudolite transmitter and receiver system. According to the measured oscillator parameters, an oscillator-induced frequency fluctuation is then generated, and added to the digital IF signal. Further simulation experiments are conducted that attempt to measure the oscillator phase noise effect on a second-order Phase Lock Loop (PLL) performance. Results indicate that the IF signal simulator considering the oscillator phase noise is able to provide software receivers with real signal dynamics, helping to evaluate the performance of signal processing algorithms on a software platform.

In this letter, a low phase-noise (PhN) oscillator is designed, implemented, and experimentally tested using an active and compact Giuseppe Peano fractal resonator as a filter with high-quality factor (QF) which acts as the frequency stabilization and selection element. The oscillation frequency corresponds to the frequency response peak of the complex QF filter. Due to the characteristics of this active filter, the oscillator PhN is highly reduced. The oscillator, operating at 3.36 GHz with 15-dBm output power, demonstrates a measured PhN of −131.5 dBc/Hz at 100-kHz offset frequency and 151.4 dBc/Hz at 1-MHz offset frequency. It is shown that the proposed oscillator outperforms the state-of-the-art microwave planar oscillators in reducing the PhN.

Millimeter-wave bands are receiving great attention for mobile radio communications due to potential availability of enormous channel bandwidths. Larger channel bandwidths are very important to meet ever increasing data rate and capacity demands of future wireless networks. At high carrier frequencies, transmitted and received signals can suffer from severe hardware impairments. We evaluate the performance of several state-of-the-art waveforms, e.g., Cyclic-Prefix (CP)-OFDM, Windowed (W)-OFDM, Pulse-shaped (P)-OFDM, Universal-Filtered (UF)-OFDM, Filter-Bank Multi-Carrier with Offset Quadrature Amplitude Modulation, and DFT-spread (DFT-s)-OFDM, in the presence of hardware impairments. In particular, waveform comparisons have been evaluated in terms of bit error rate, error vector magnitude, and spectral confinement subject to oscillator phase noise and nonlinear power amplifier. It is observed that all waveforms perform similarly subject to hardware impairments—making CP-OFDM with low complexity filtering/windowing operations an attractive option to improve the spectral confinement. One major drawback of multi-carrier waveforms is the high peak-to-average power ratio (PAPR). Various low complexity PAPR reduction techniques for OFDM have been evaluated subject to hardware impairments. It is observed that in case of nonlinear PA and high power transmission, these simple PAPR reduction schemes can achieve similar performance as compared to DFT-s-OFDM, making OFDM also suitable for coverage limited scenarios where power efficiency is important.

We analyze the performance of a helmet-based frequency modulated continuous wave (FMCW) radar system for use in impact prediction in contact sports, or other risky environments. It has been shown that the head trauma and concussions can have significant detrimental effects on the health and quality life of contact sport athletes, from the high school to professional level. Impact prediction capability could be an important part of a comprehensive, helmet-based system for mitigating the neurological damage caused by impacts. Mitigation strategies include using imminent impact information in an audible warning system, or dynamic preloading and control of an active helmet suspension. Our analysis centers on the prediction of an impact offset parameter (and its uncertainty) in a representative player interaction scenario. We consider realistic radar measurement specifications consistent with our player interaction scenario, and COTS radar hardware, including oscillator phase noise, operation frequency, sweep frequency, bandwidth, range, target scattering cross-section, and antenna gain.

A high-resolution, high-bandwidth, and noise-scrambling, time-to-digital converter (TDC) is presented. Its architecture, which exploits harmonics in ring oscillators, provides a sample-and-hold mechanism in the form of relative phase. This storage mechanism is highly insensitive to noise and allows for oversampling between input events, therefore, can be designed for very high bandwidth. It can achieve lower quantization noise with fewer measurements than noise-shaping TDCs. This paper presents the architecture in detail, an in-depth analysis of noise sensitivity of the time storage mechanism, and the results from a prototype implemented in a 28-nm CMOS process.

When an antenna vibrates, it induces phase noise on the signals that it transmits and receives. This noise source is significant for microwave and millimeter-wave systems operating in high-vibration environments that require low phase noise at small frequency offsets. The purpose of this paper is to derive equations to compute phase noise from vibration parameters and to validate the equations with measurements. It is shown that the induced phase noise varies as ${f}_{v}^{-4}$ , where ${f}_{v}$ is the frequency of vibration. The results are then compared to the phase noise induced on an oscillator by vibration to determine the oscillator g sensitivity such that the oscillator and antenna phase noise contributions are equal. For state-of-the-art low-g-sensitivity oscillators, the phase noise contribution of the antenna can dominate at vibrational frequencies up to several kilohertz. The vibrational phase noise sensitivity of the antenna is also larger than the reported vibrational sensitivity of coaxial cables up to at least 1000-Hz vibrational frequencies and bandpass filters up to 300–1000-Hz vibrational frequencies depending on the filter quality factor.