High Power Noise Research Articles

A New Extended State Observer with Low Sensitivity to High Frequency Noise and Low Gain Power

Linear Extended State Observer (LESO) with a large gain wo leads to faster estimation error convergence. But a high gain LESO is sensitive to high frequency measurement noise and its digital implementation is rather complex. To address the above issues, for a given n-th order plant, a new 2n-th order extended state observer is proposed. The proposed observer, while preserving the fast convergence property of LESO, has a lower gain power of 2 and is less sensitive to high frequency measurement noise. And the new observer can be easily tuned with gain ωo.

Снижение мощности высокочастотных помех в сигнале управления автоматических систем гребенчатыми фильтрами

The article addresses the matter of reducing the power of high-frequency noise in the control signal produced by industrial automatic systems through the use of algorithms implementing the properties of comb filters in microprocessor controllers. The specific features relating to the frequency responses of open- and closed-loop automatic control systems of industrial facilities are analyzed - both taken alone and in combination with the characteristics of comb filters. The frequency properties of three filter groups that are conventionally used in continuous automatic control systems are compared with three groups of comb filters that implement similar functions. As applied to control tasks, such filters include real differentiating sections or first-order high-pass filters, first-order lag sections or low-pass filters, and proportional sections. The ratios between the parameters of continuous filters and comb filters at which their frequency properties coincide in the operating frequency band are determined. These ratios known, it becomes possible to synthesize the controllers of systems using the existing techniques. It is shown that the amplitude-frequency responses of comb filters have dips in the high-frequency band, due to which the high frequency noise power is finally decreased by up to 30%. The advantage of comb filters in control systems lies in simplicity of implementing them in digital form in a microprocessor controller. The application of comb filters in automatic control systems makes it possible to cut undesirable harmonic noise of large amplitude in the control signal.

Low power CMOS variable gain amplifier design for a multistandard receiver WLAN/WIMAX/LTE

This paper deals with a new compact low-power variable gain amplifier (VGA) architecture design for wireless communication multistandard receivers. The proposed VGA is a two stages cascaded topology that includes a folded cascode operational transconductance amplifier stage and a VGA core. The new “cell” structure has been introduced to demonstrate the performance enhancement with the use of only one VGA stage. The heuristic method is used to optimize the proposed circuit performance for high gain, low noise and low power consumption. This circuit is implemented and simulated using device-level description of TSMC 0.18 µm CMOS process. The simulation results indicate that the new VGA achieves a gain ranging from a minimum of − 25 dB toa maximum reaching 79 dB with a large bandwidth of 200 MHz. The designed VGA circuit acquires a noise figure less than 18 dB, an input referred noise of around 9.3 nV2/Hz and the third order intercept point measured at the input (IIP3) of 15 dBm. The proposed circuit consumes only 0.5 mW under 1.8 V supply voltage.

Two-Stage Single-Relay Channel Model for In-Home Broadband PLC Systems

This paper discusses the two-stage single-relay channel model for in-home broadband power line communication links with up to two hops. This channel model consists of the concatenation of two single-relay channels that can result in eight configurations; however, only five of them are analyzed in this work since they cover up to one relay availability. In this context, a discussion addressing both amplify-and-forward and decode-and-forward cooperative protocols at relay node and maximal ratio combining at destination node is carried out. As the power line channels are frequency selective, the attenuation profile increases along with both distance and frequency, and the additive noise is colored, we discuss achievable data rate analyses using a data set covering the frequency band from 1.7 to 100 MHz, under sum power constraint. Based on the attained results, we state that the two-stage single-relay channel model is the best option for in-home broadband power line communication systems when the source-to-destination link is severely degraded (e.g., high signal attenuation and/or high-power noise presence), while the two-hop channel model is more appropriate when the channel degradation is not severe. Moreover, we show that the single-relay channel model may be remarkably outperformed by the two-stage single-relay channel model.

Knowledge-Aided Target Detection for Multistatic Passive Radar

This paper studies the detection problem for multistatic passive radar. We consider scenarios where prior knowledge about the spectrum and peak-to-average ratio (PAR) of the non-cooperative illuminators of opportunity (IOs) is available. We develop several knowledge-aided (KA) detectors within the framework of the generalized likelihood ratio test (GLRT) to exploit such prior knowledge. Particularly, the knowledge about the bandwidth of the transmitted signal is employed to suppress the out-of-band noise, and the knowledge about the PAR constraint is exploited to eliminate the remaining high-power noise. The challenge of unknown spectrum condition is also addressed, where block sparse Bayesian learning (BSBL) is exploited to derive the maximum-likelihood estimates (MLEs) of the unknown, temporally correlated signal. The numerical results indicate that the proposed KA detectors offer significant performance improvements compared with the traditional detectors, which do not exploit such prior information.

Neural Spike Digital Detector on FPGA

This paper presents a multidisciplinary experiment where a population of neurons, dissociated from rat hippocampi, has been cultivated over a CMOS-based micro-electrode array (MEA) and its electrical activity has been detected and mapped by an advanced spike-sorting algorithm implemented on FPGA. MEAs are characterized by low signal-to-noise ratios caused by both the contactless sensing of weak extracellular voltages and the high noise power coming from cells and analog electronics signal processing. This low SNR forces to utilize advanced noise rejection algorithms to separate relevant neural activity from noise, which are usually implemented via software/off-line. However, off-line detection of neural spikes cannot be obviously used for real-time electrical stimulation. In this scenario, this paper presents a proper FPGA-based system capable to detect in real-time neural spikes from background noise. The output signals of the proposed system provide real-time spatial and temporal information about the culture electrical activity and the noise power distribution with a minimum latency of 165 ns. The output bit-stream can be further utilized to detect synchronous activity within the neural network.

A 0.49–13.3 MHz Tunable Fourth-Order LPF with Complex Poles Achieving 28.7 dBm OIP3

A novel switched-capacitor low-pass filter architecture is presented. In the proposed scheme, a feedback path is added to a charge-rotating real-pole filter to implement complex poles. The selectivity is enhanced, and the in-band loss is reduced compared with the real-pole filter. The output thermal noise level and the tuning range are both close to those of the real-pole filter. These features make the filter suitable for high speed, low noise, and low power applications. A fourth-order filter prototype was implemented in a 180-nm CMOS technology. The measured in-band loss is reduced by 3.3 dB compared with that of a real-pole filter. The sampling rate of the filter is programmable from 65 to 300 MS/s with a constant dc gain. The 3-dB cut-off frequency of the filter can be tuned from 490 to 13.3 MHz with over 100-dB maximum stop-band rejection. The measured in-band third-order output intercept point is 28.7 dBm, and the averaged spot noise is 6.54 nV/√Hz. The filter consumes 4.3 mW from a 1.8 V supply.

A CMOS Low-Power Digital Variable Gain Amplifier Design for a Cognitive Radio Receiver “Application for IEEE 802.22 Standard”

This paper presents the design of a new Digital Variable Gain Amplifier cell (DVGA). The proposed circuit based on transconductance, gm, amplifier and a transconductance amplifier is analyzed and designed for a cognitive radio receiver. The variable-gain amplifier (VGA) proposed consists of a digital control block, an auxiliary pair to retain a constant current density, and offers a gain-independent bandwidth (BW). A novel cell structure is designed for high gain, high BW, low power consumption and low Noise Figure (NF). The Heuristic Method is used to optimize the proposed circuit performance for high gain, low noise and low power consumption. This circuit is implemented and simulated using device-level description of TSMC 0.18[Formula: see text][Formula: see text]m CMOS process. Simulation results show that the DVGA can provide a gain variation range of 54[Formula: see text]dB (from 54[Formula: see text]dB to 0[Formula: see text]dB) with a 3[Formula: see text]dB BW over more than 110[Formula: see text]MHz. The circuit consumes the maximum power of 0.65[Formula: see text]mW from a 1.8[Formula: see text]V supply.

High mobility channel estimation method based on improved basis expansion model

In this paper, the problem of high mobility channel estimation in the Long-Term Evolution for Railway (LTE-R) communication system is investigated. By using a Basis Expansion Model (BEM), the channel impulse response is modeled as the sum of several basis functions multiplied by coefficients. By estimating the basis function coefficients, the fast time-varying channel can be approximated. In order to reduce the estimation error resulting from the high frequency basis function, the Generalized Complex Exponential BEM (GCE-BEM) is modified to form an Improved GCE-BEM (IGCE-BEM) by adding a correction coefficient to the basis function. Moreover, an Improved Baseline Tilting (IBT) method is proposed to reduce the Gibbs effect. In addition, linear interpolation, Gauss interpolation, and three-order Hermite interpolation are adopted to obtain the channel impulse response at non pilot locations based on the channel estimation results at pilot positions. The simulation results show that the IGCE-BEM outperforms the CE-BEM and GCE-BEM in terms of the Normalized Mean Squared Error (NMSE). The IBT method is better than the BT method in reducing the Gibbs effect. In addition, combined with the IBT, the IGCE-BEM also has low NMSE under high moving speed and high noise power. The performance of the three-order Hermite interpolation method is higher than that of the linear interpolation and Gauss interpolation approaches.

Electronics and triggering challenges for the CMS High Granularity Calorimeter

The High Granularity Calorimeter (HGCAL), presently being designed by the CMS collaboration to replace the CMS endcap calorimeters for the High Luminosity phase of LHC, will feature six million channels distributed over 52 longitudinal layers. The requirements for the front-end electronics are extremely challenging, including high dynamic range (0.2 fC–10 pC), low noise (∼2000 e− to be able to calibrate on single minimum ionising particles throughout the detector lifetime) and low power consumption (∼20 mW/channel), as well as the need to select and transmit trigger information with a high granularity. Exploiting the intrinsic precision-timing capabilities of silicon sensors also requires careful design of the front-end electronics as well as the whole system, particularly clock distribution. The harsh radiation environment and requirement to keep the whole detector as dense as possible will require novel solutions to the on-detector electronics layout. Processing the data from the HGCAL imposes equally large challenges on the off-detector electronics, both for the hardware and incorporated algorithms. We present an overview of the complete electronics architecture, as well as the performance of prototype components and algorithms.

64-Gb/s SSB-PAM4 Transmission Over 120-km Dispersion-Uncompensated SSMF With Blind Nonlinear Equalization, Adaptive Noise-Whitening Postfilter and MLSD

A novel low-complexity digital signal processing solution is presented to compensate the impairments of limited bandwidth and nonlinearity. It is based on the equalizer, adaptive noise-whitening postfilter, and maximum likelihood sequence detection (MLSD). The system performance loss is induced by higher noise power at the signal band edges after the equalizer can be mitigated by the postfilter and MLSD. Given the above structure, it is possible to enrich the equalizer by providing nonlinear compensation capability. A memory polynomial equalizer (MPE), instead of Volterra equalizer (VE), is applied as the equalizer to compensate the nonlinearity impairments in order to make a tradeoff between complexity and performance. For the adaption of MPE, the blindly adaptive multistep-size decision-directed least-mean-square algorithm is selected. By using a dual-drive Mach–Zehnder and direct detection, 64-Gb/s single-sideband 4-ary pulse amplitude modulation (SSB-PAM4) transmission over 120-km dispersion-uncompensated standard single-mode fiber (SSMF) with 10-dB bandwidth roughly 13.5 GHz is experimentally demonstrated. Given a 20% overhead soft-decision forward-error correction with bit error rate threshold of $2\times 10^{{-2}}$ , the dispersion-uncompensated SSMF transmission distance can be significantly increased from 40 to 120 km with the proposed receiver side solution. The optical signal noise ratio performances for different fiber reach and receiver structure are investigated. Furthermore, we compare the computational complexity of MPE with VE and conclude that MPE can substantially reduce computation complexity with negligible performance loss.

Transmit power and bits/channel use adaption in competitive cognitive radio networks

In this paper, we propose an optimization framework to determine the distribution of power and bits/channel use to secondary users in a competitive cognitive radio networks. The objectives of the optimization framework are to minimize total transmission power, maximize total bits/channel use and also to maintain quality of service. An upper bound on probability of bit error and lower bound on bits/channel use requirement of secondary users are considered as quality of service. The optimization problem is also constrained by total power budget across channels for a user. Simulating the framework in a centralized manner shows that more transmit power is required to allocate in a channel with higher noise power. However, allocation of bits/channel use is directly proportional to signal to interference plus noise power ratio. The proposed framework is more capable of supporting high bits/channel use requirement than existing resource allocation framework. We also develop the game theoretic user based distributed approach of the proposed framework. We see that user based distributed solution also follows centralized solution.

An Assessment of Non-geophysical Effects in Spaceborne GNSS Reflectometry Data From the UK TechDemoSat-1 Mission

An assessment of non-geophysical effects in spaceborne global navigation satellite system reflectometry (GNSS-R) data from the UK TechDemoSat-1 (TDS-1) mission is presented. TDS-1 was launched in July 2014 and provides the first new spaceborne GNSS-R data since the pioneering UK-disaster monitoring constellation experiment in 2003. Non-geophysical factors evaluated include ambient L-band noise, instrument operating mode, and platform-related parameters. The findings are particularly relevant to users of uncalibrated GNSS-R signals for the retrieval of geophysical properties of the Earth surface. Substantial attitude adjustments of the TDS-1 platform are occasionally found to occur that introduce large uncertainties in parts of the TDS-1 GNSS-R dataset, particularly for specular points located outside the main beam of the nadir antenna where even small attitude errors can lead to large inaccuracies in the geophysical inversion. Out of eclipse however, attitude adjustments typically remain smaller than 1.5°, with larger deviations of up to 10° affecting less than 5% of the overall sun-lit data. Global maps of L1 ambient noise are presented for both automatic and programmed gain modes of the receiver, revealing persistent L-band noise hotspots along the Equator that can reach up to 2.5 dB, most likely associated with surface reflection of signals from other GNSS transmitters and constellations. Sporadic high-power noise events observed in certain regions point to sources of human origin. Relevant conclusions of this study are that platform attitude knowledge is essential and that radiometric calibration of GNSS-R signals should be used whenever possible. Care should be taken when considering using noise measurements over the equatorial oceans for calibration purposes, as ambient noise and correlated noise in delay–Doppler maps both show more variation than might be expected over these regions.

Local-polynomial-approximation-based phase unwrapping using state space analysis

A new method of phase unwrapping is proposed for the absolute phase estimation based on the first-order polynomial phase approximation within a symmetric window generated around each pixel. The accurate estimation of polynomial coefficients is performed by formulating them as the elements of a state vector in a state space model. The extended Kalman filter offers a robust approach for the state estimation with the capability of handling high noise power. The polynomial coefficients estimates obtained at a given pixel are used as the initial conditions of the Kalman filter for its neighboring pixel, which results in the unwrapped phase estimation. The simulation and experimental results validate the performance of the proposed phase unwrapping method along with its ability of handling the masked phase fringe patterns with the help of a predefined binary mask and a pixel selection strategy.

A 20 Gb/s CMOS Optical Receiver With Limited-Bandwidth Front End and Local Feedback IIR-DFE

Implementation of highly integrated optical receivers in CMOS promises low cost, but combining high gain, low noise, high bandwidth, and low power in a CMOS transimpedance amplifier is a challenge. Fortunately, the sensitivity of an optical receiver is improved by limiting its front-end bandwidth far below the symbol rate and using equalization to eliminate the resulting intersymbol interference (ISI). Analysis reveals that when using a decision-feedback equalizer (DFE) to cancel all postcursor ISI, receiver sensitivity is optimized by taking a front-end bandwidth as low as 0.12 ${f}_{\mathrm{ bit}}$ , depending upon the frequency response and noise spectrum assumed for the front end. This paper presents a 20 Gb/s optical receiver with a front-end bandwidth of 3 GHz. The front end is designed to have an approximately first-order response, ensuring only postcursor ISI, which may be efficiently canceled with a first-order infinite-impulse response DFE (IIR-DFE). An IIR-DFE circuit is also proposed that obviates the need for an explicit full-rate multiplexor. Fabricated in 65 nm CMOS, the receiver achieves 0.705 pJ/b efficiency with the IIR-DFE consuming 150 fJ/b. Using a photodiode with 12 GHz analog bandwidth and responsivity of 0.5 A/W, the receiver has a sensitivity of −5.8 dBm optically modulated amplitude.

Optical steganography transmission of optical CDMA signals over a public BPSK channel

Purpose – The purpose of this paper is to propose a new optical steganography framework that can be applied to public optical binary phase-shift keying (BPSK) systems by transmitting a stealth spectrum-amplitude-coded optical code-division multiple-access signal through a BPSK link. Design/methodology/approach – By using high-dispersion elements, the stealth data pulses temporally stretch and the amplitude of the signal decreases after stretching. Thus, the signal can be hidden underneath the public signal and system noise. At the receiver end, a polarizer is used for removing the public BPSK signal and the stealth signal is successfully recovered by a balanced detector. Findings – In a simulation, the bit-error rate (BER) performance improved when the stealth power increased. Research limitations/implications – The BER performance worsens when the noise power become large. Future work will consider increasing the system performance during high-noise power situation. Practical implications – By properly adjusting the power of the amplified spontaneous emission noise, the stealth signal can be hidden well in the public channel while producing minimal influence on the public BPSK signal. Originality/value – In conclusion, the proposed optical steganography framework makes it more difficult for eavesdroppers to detect and intercept the hidden stealth channel under public transmission, even when using a dispersion compensation scheme.

Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation.

This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. This suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.

Incoherent signal source resolution based on coherent aperture synthesis

A technique is proposed for resolving two incoherent signal sources of the same frequency and significantly different intensities with similar angular coordinates. The technique is based on aperture synthesis of a receiving array, first, by the signal of higher-power source and the estimate of its angular coordinate with subsequent subtraction of the signal spectrum from the angular spectrum of the received field. This makes it possible to achieve aperture synthesis and estimate the angle of arrival of a higher-power signal. Thus, the technique is of interest not only for synthesized apertures, but also for arrays with a filled aperture, since it eliminates the restrictions imposed by the presence of lateral lobes of the array response. Our mathematical simulation data demonstrate the efficiency of this technique in the detection and location of weak signals against the background of high-power noise sources even at their close angular positions.

A full W-band low noise amplifier module for millimeter-wave applications**Project supported by the Major Program of the National Natural Science Foundation of China (No. 61434006) and the National Natural Science Foundation of China (No. 61401457).

A full W-band low noise amplifier (LNA) module is designed and fabricated. A broadband transition is introduced in this module. The proposed transition is designed, optimized based on the results from numerical simulations. The results show that 1 dB bandwidth of the transition ranges from 61 to 117 GHz. For the purpose of verification, two transitions in back-to-back connection are measured. The results show that transmission loss is only about 0.9–1.7 dB. This transition is used to interface integrated circuits to waveguide components. The characteristic of the LNA module is measured after assembly. It exhibits a broad bandwidth of 75 to 110 GHz, and has a small signal gain above 21 dB. The noise figure is lower than 5.2 dB throughout the entire W-band (below 3 dB from 89 to 95 GHz) at room temperature. The proposed LNA module exhibits potential for millimeter wave applications due to its high small signal gain, low noise, and low DC power consumption.

J-band amplifier design using gain-enhanced cascodes in 0.13 μm SiGe

This paper presents two J-band amplifiers in different 0.13 μm SiGe technologies: a small signal amplifier (SSA) in a technology in which never before gain has been shown over 200 GHz; and a low noise amplifier (LNA) design for 230 GHz applications in an advanced SiGe HBT technology with higher fT/fmax, demonstrating the combination of high gain, low noise, and low power in a single amplifier. Both circuits consist of a four-stage pseudo-differential cascode topology. By employing series–series feedback at the single-stage level the small-signal gain is increased, enabling circuit operation at high-frequencies and with improved efficiency, while maintaining unconditional stability. The SSA was fabricated in a SiGe BiCMOS technology by Infineon with fT/fmax values of 250/360 GHz. It has measured 19.5 dB gain at 212 GHz with a 3 dB bandwidth of 21 GHz. It draws 65 mA from a 3.3 V supply. On the other hand, a LNA was designed in a SiGe BiCMOS technology by IHP with fT/fmaxof 300/450 GHz. The LNA has measured 22.5 dB gain at 233 GHz with a 3 dB bandwidth of 10 GHz and a simulated noise figure of 12.5 dB. The LNA draws only 17 mA from a 4 V supply. The design methodology, which led to these record results, is described in detail with the LNA as an example.