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Full-Duplex (FD) communication can revolutionize wireless communications as it doubles spectral efficiency and offers numerous other advantages over a half-duplex (HD) system. In this paper, we present a novel and practical joint hybrid beamforming (HYBF) and combining scheme for millimeter-wave (mmWave) massive MIMO FD system for weighted sum-rate (WSR) maximization with multi-antenna HD uplink and downlink users with non-ideal hardware.Moreover, we present a novel interference and self-interference (SI) aware optimal power allocation scheme for the optimal beamforming directions. The analog processing stage is assumed to be quantized, and both the unit-modulus and unconstrained cases are considered.Moreover, compared to the traditional sum-power constraints, the proposed algorithm is designed under the joint sum-power and the practical per-antenna power constraints. To model the non-ideal hardware of a hybrid FD transceiver, we extend the traditional limited dynamic range (LDR) noise model to mmWave. Our HYBF design relies on alternating optimization based on the minorization-maximization method. We investigate the maximum achievable gain of a hybrid FD system with different levels of the LDR noise variance and with different numbers of radio-frequency (RF) chains over a HD system. Simulation results show that the mmWave massive MIMO FD systems can significantly outperform the fully digital HD systems with only a few RF chains if the LDR noise generated from the limited number of RF chains available is low. If the LDR noise variance dominates, FD communication with HYBF results to be disadvantageous than a HD system.

The range of transmitters, detectors and other components that can be used in optical wireless links means that they can have a wide variety of frequency responses. Both pre- and post- equalization have been used in optical wireless systems to increase data rates. Pre-equalization has the advantage that noise impairments due to equalization can be minimised. However, the variety of pre-equalizer transfer functions, which can be easily created using analog circuits, is limited by the frequency responses of these circuits. Consequently, it may not be possible to equalize some optical wireless links with analog circuit-based pre-equalizers. In this paper a flexible digital pre-equalization scheme that can equalize complex frequency responses is described. The flexibility and the applicability of the scheme is also demonstrated using two example systems, including one that incorporates a fluorescent optical fiber to create a wide-field-of-view receiver for handheld devices. In particular, the bandwidths of the two example systems have been increased to over 500 MHz and to 350 MHz, resulting in at least a three-fold increase in data rate without any post-equalization. The authors believe that this is the first time such significant improvements in on-off-keying data rates have been demonstrated in systems with a relatively complex frequency response and a limited dynamic range.

This article analyses the effects of system distortions (crosstalk and channel imbalance), Faraday rotation and system noise on estimates of the cross-polarized backscattering coefficient, ${\boldsymbol{\sigma }}_{{{\bf hv}}}^0$, by a spaceborne synthetic aperture radar. Modeling the unknown system errors and noise by a joint complex Gaussian distribution allows analytic first-order approximations to the mean and variance of the error in ${\boldsymbol{\sigma }}_{{{\bf hv}}}^0$ to be derived that do not depend on the SAR operating frequency. Simulation shows these approximations to be very accurate, given the statistical model and the expected magnitudes of system errors and noise for the P-band instrument to be carried by the European Space Agency BIOMASS mission. Simulation further shows that the ${\boldsymbol{\sigma }}_{{{\bf hv}}}^0$ errors are Gaussian distributed, so their exceedance probabilities can be calculated from just the analytic expressions for the mean and variance of the errors. Exceedance probabilities for above-ground biomass (AGB) can then be calculated under a power law relation between ${\boldsymbol{\sigma }}_{{{\bf hv}}}^0{{\rm{\sigma }}_{{\rm{hv}}}}$ and AGB that is consistent with P-band observations. This allows tradeoff curves between crosstalk and channel imbalance (shown to be segments of hyperbolas) to be calculated, along which the relative error in AGB is within a given percentage of its true value, from which limits on the permissible size of the errors can be determined if BIOMASS mission requirements are to be met.

The Boltzmann machine (BM) and restricted Boltzmann machine (RBM) models are representative stochastic neural networks, in which neuron states are determined by stochastic activation functions. They are widely used in many applications. However, when analog circuits are used to realize a neural network, noise are not avoidable. The noise could come from external environments, such as power supplies and thermal noise, and they will affect the neurons’ stochastic behaviour in the BM and RBM models. Hence it is important to theoretically study how the noise affect the operation of the BM and RBM models. To best of our knowledge, there are little works related to the analysis on noisy BMs and noisy RBMs. This paper considers that there are additive noise in the inputs of the neurons, and theoretically studies the behaviors of the two models under this imperfect condition. It is found that the effect of additive noise is similar to increasing the temperature factors of the two models. Since the input noise may make the networks to have wrong stochastic behaviour, there is Kullback Leibler (KL) divergence loss in noisy BMs and noisy RBMs. Based on the Gaussian-distributed noise assumption, a noise compensation method is proposed to suppress the effect of additive noise. Experiments show that the proposed noise compensation method can greatly suppress the KL divergence loss. In addition, from the experimental results, our method is also effective for handling non-Gaussian noise.

This paper presents two designs of a capacitively-coupled chopper instrumentation amplifier (CCIA) successfully implemented in 28 nm CMOS for biopotential sensing applications. The first design is a compact CCIA using offset-blocking for chopping ripple reduction, DC servo loop (DSL) for electrode offset ( $V_{\mathrm {EOS}}$ ) suppression, and a high pass filter (HPF) for handling common-mode (CM) artifacts. An inverter-based self-biased input stage is used for noise and power efficiency. The two gain stages of the CCIA achieve a low-frequency open-loop gain >80 dB. Realized in an area of 0.05 mm2, the CCIA handles $V_{\mathrm {EOS}}$ up to 50 mV and tolerates CM artifacts up to $1.5~V_{\mathrm {pp}}$ . The CCIA achieves a mid-band gain of 39.5 dB with a 1 kHz bandwidth by consuming $1~\mu \text{W}$ . The integrated input-referred noise (IRN) over 200 Hz bandwidth is $2.15~\mu V_{\mathrm {rms}}$ . The second design presents a dual-channel CCIA (DCCIA) using an orthogonal frequency chopping for multi-sensor array applications. An inverter-based input stage is used for noise efficiency. The measured results show that the DCCIA achieves a low-frequency gain of 39.5 dB with a 3-dB bandwidth up to 1 kHz by consuming $0.71~\mu \text{W}$ per channel. The measured noise density is 136 nV/ $\surd $ Hz with an integrated noise of $2.67~\mu V_{\mathrm {rms}}$ over 200 Hz bandwidth. The DCCIA suppresses $V_{\mathrm {EOS}}$ up to 50 mV using the DSL. Realized in a compact area of 0.04 mm2 per channel, an excellent gain matching error of 0.29% is achieved with the crosstalk higher than 58 dB between the channels. This work is a measured report on the instrumentation amplifier using, to the best of the authors’ knowledge, one of the smallest CMOS process nodes.

1/f noise provides essential information on the interface trapping effect as well as the scattering mechanism in transistors. In this work, a systematic 1/f noise study has been carried out on the recessed-gate enhancement-mode (E-mode) GaN MOS-HEMTs under electrical and thermal stress together with the depletion-mode (D-mode) counterpart. Low-frequency (1–1000 Hz) measurement has been performed at room (25 °C) and elevated (100 °C) temperatures at different carrier densities at the drain bias of 2 V and 10 V. The results show the E-mode device has much better noise characteristics under high voltage and high temperature compared with the D-mode counterpart. Moreover, charge-noise model reveals that the improved noise behavior of the E-mode device at high density and high drain bias at 100 °C originating from the energy band alignment at high biases, where the D-mode device suffers from extra charge trapping scattering in the gate edge near the gate-to-drain access region.

A novel carrier stored trench bipolar transistor (CSTBT) with split gate (SG) and recessed emitter trench (SGRET CSTBT) is proposed. The proposed device features a SG structure with thicker oxide layer under the trench gate and recessed trench emitter, respectively. Compared with the conventional CSTBT with recessed emitter trench (RET CSTBT), the proposed device not only significantly reduces the gate-collector capacitance ( ${C} _{\mathrm{ GC}}$ ) but also alleviates the negative impact of the heavily doped n-type carrier stored layer on the breakdown voltage (BV). Simulation results show that with the similar BV of about 650V, the on-state voltage drop ( ${V} _{\mathrm{ ceon}}$ ) at ${J} _{\mathrm{ ce}}$ =200A/cm2 for the proposed SGRET CSTBT is only 1.11V, which is 0.19V lower than that of the conventional RET CSTBT. Moreover, compared with the conventional RET CSTBT, the ${C} _{\mathrm{ GC}}$ at the ${V} _{\mathrm{ ce}}$ of 25V, total gate charge ( ${Q} _{\mathrm{ G}}$ ) and miller plateau charge ( ${Q} _{\mathrm{ GC}}$ ) for the proposed device are reduced by 84.3%, 38.6% and 51.6%, respectively. As a result, the trade-off relationship between the ${V} _{\mathrm{ ceon}}$ and turn-off loss ( ${E} _{\mathrm{ off}}$ ) as well as trade-off relationship between the turn-on loss ( ${E} _{\mathrm{ on}}$ ) and $\text{d}{V} _{\mathrm{ ak}} / \text{d}{t}$ of the free-wheeling diode (FWD) are significantly improved for the proposed device. At the same ${V} _{\mathrm{ ceon}}$ of 1.16V, the ${E} _{\mathrm{ off}}$ is reduced from 9.2mJ/cm2 of the conventional one to 3.3mJ/cm2 of the proposed device. At the same ${E} _{\mathrm{ on}}$ of 8.3mJ/cm2, the $\text{d}{V} _{\mathrm{ ak}} / \text{d}{t}$ of FWD for the proposed device is reduced by 24.5% compared with that of the conventional RET CSTBT, which significantly suppresses the EMI noise.

As the limited communication spectrum can not meet the demand of the exponential growth of intelligent connected devices in the internet of things(IoT) and typical smart city applications, in this paper, we propose a tractable spectrum sensing method based on Rao detection over non-Gaussian noise, such as generalized Gaussian noise(GGN), Gaussian mixture noise(GMN) and symmetric alpha-stable distribution ( $\text{S}\alpha \text{S}$ ) noise, multi-path fading channels environment to alleviate the issue of spectrum scarcity. In this method, there are unknown parameters in the multi-path fading channels. When the probability density function (P.D.F.) of non-Gaussian noise has a closed-form expression, the spectrum sensing method based on Rao detection is used. Otherwise the P.D.F. for $\text{S}\alpha \text{S}$ noise is estimated firstly by using non-parametric kernel estimation method, which addresses the issue that $\text{S}\alpha \text{S}$ noise has no closed-form P.D.F. expression, and then the performance of spectrum sensing is derived based on the theory of Rao detection in multi-path fading channels over typical smart city applications. Simulation results show that the accuracy of estimated P.D.F. for $\text{S}\alpha \text{S}$ noise and the performance of spectrum sensing under different $\alpha $ values over indoor, outdoor, and vehicle fading channels environment.

Communication systems are affected by channel distortions. Impulsive noise is one of the significant factors for channel impairments. The standard additive white Gaussian noise (AWGN) channel model and conventional estimation algorithms like least mean square (LMS) and its variants tend to be ineffective under such conditions. This paper presents a robust adaptive channel estimation algorithm using the Geman-McClure estimator in a diffusion-based distributed network. The analytical study on mean stability and mean square analysis is carried out under two separate noise statistics: Symmetric $\alpha $ -stable ( $\text{S}\alpha \text{S}$ ) and Bernoulli-Gaussian (BG) distribution. The computer simulations confirm the proposed algorithm’s competitive robustness compared to the Maximum Correntropy Criterion and Minimum Kernel Risk Sensitive Loss algorithms at a high impulsive noise environment without exponential cost function. Further, the efficiency is also verified by simulating the bit error rate by designing a minimum mean square error (MMSE) equalizer with the estimated coefficients.

To acquire daytime land surface temperature (LST) in thin cirrus cloudy skies, we have developed a three-channel LST retrieval algorithm based on a widely used two-channel LST retrieval algorithm for the clear-sky conditions. In this algorithm, the LST is expressed as a multiple linear function of MODIS channels 29, 31 and 32 with the coefficients of the linear function dependent on the cirrus optical depth (COD) and cirrus effective radius (R). The influences from land surface emissivities (LSEs) are also considered in this algorithm. The simulated dataset shows that the LST could be estimated using the proposed algorithm with the root mean squire error (RMSE) less than 2.2 K in thin cirrus cloudy skies (COD less than 0.7) when viewing zenith angle (VZA) equivalent to 0°. As VZA is equivalent to 60°, the maximum RMSE are 2.7 K. The widely used generalized split-window (GSW) algorithm proposed for clear-sky conditions are used in cirrus cloudy skies, and the RMSEs of GSW algorithm estimated LST are 16.89 K and 22.32 K for VZA =0° and VZA =60° respectively when COD is 0.7. It indicates that the proposed three-channel algorithm can significantly improve the LST retrieval accuracy using thermal infrared data in cirrus cloudy skies. To estimate the LST errors caused by the uncertainties of COD, R, LSE and instrument noise, a sensitivity analysis was performed. It shows that the accuracy of cirrus COD is more important for the retrieval of LST compared with other parameters. The maximum total LST errors, taking into account all the input parameters’ uncertainty and algorithm error itself, are 3.8 K and 4.3 K when VZA =0° and VZA =60° respectively.

Many studies on deep learning-based speech enhancement (SE) utilizing the computational auditory scene analysis method typically employs the ideal binary mask or the ideal ratio mask to reconstruct the enhanced speech signal. However, many SE applications in real scenarios demand a desirable balance between denoising capability and computational cost. In this study, first, an improvement over the ideal ratio mask to attain more superior SE performance is proposed through introducing an efficient adaptive correlation-based factor for adjusting the ratio mask. The proposed method exploits the correlation coefficients among the noisy speech, noise and clean speech to effectively re-distribute the power ratio of the speech and noise during the ratio mask construction phase. Second, to make the supervised SE system more computationally-efficient, quantization techniques are considered to reduce the number of bits needed to represent floating numbers, leading to a more compact SE model. The proposed quantized correlation mask is utilized in conjunction with a 4-layer deep neural network (DNN-QCM) comprising dropout regulation, pre-training and noise-aware training to derive a robust and high-order mapping in enhancement, and to improve generalization capability in unseen conditions. Results show that the quantized correlation mask outperforms the conventional ratio mask representation and the other SE algorithms used for comparison. When compared to a DNN with ideal ratio mask as its learning targets, the DNN-QCM provided an improvement of approximately 6.5% in the short-time objective intelligibility score and 11.0% in the perceptual evaluation of speech quality score. The introduction of the quantization method can reduce the neural network weights to a 5-bit representation from a 32-bit, while effectively suppressing stationary and non-stationary noise. Timing analyses also show that with the techniques incorporated in the proposed DNN-QCM system to increase its compactness, the training and inference time can be reduced by 15.7% and 10.5%, respectively.

In this study, a symmetric polarization-division-multiplexing (PDM) wavelength-division-multiplexing passive optical network (WDM-PON) with fiber to the extension (FTTE) architecture is presented and investigated. The proposed PON can also avoid the Rayleigh backscattering (RB) interference noise. Here, each WDM wavelength can produce 25 Gbit/s on-off keying (OOK) and 10 Gbit/s OOK modulation channels simultaneously in x- and y-polarizations (Polx and Poly) through PDM method for 25 and 105 km single-mode fiber (SMF) transmissions without dispersion compensation. The measured minimal power budget of 25 and 10 Gbit/s downstream and upstream signals are 29 and 35.1 dB and 29.8 and 31.5 dB, respectively, at the forward error correction (FEC) target. Therefore, the proposed PDM WDM-PON architecture can not only offer symmetric 35 Gbit/s downstream and upstream connections by the dual-polarized wavelength, but also can avoid the RB-induced interference noise. In addition, the presented dual-polarized downstream signal also can provide information security in physical layer, when the unauthorized user occupies unlawfully.

Silicon nitride waveguide (Si3N4), is used as the most important sensitive device because of its excellent high-polarizing characteristics. It has the potential to build the miniaturized, high-precision resonant integrated optical gyroscope (RIOG) in recent years. However, the back-reflection caused by the refractive index difference between the Si3N4 waveguide and the pigtail fiber has a non-negligible impact on the accuracy of the gyroscope. In this paper, we propose a method to suppress the back-reflection of the end face of the Si3N4 waveguide resonator. We use the Fimmprop module of the simulation software Photon Design to simulate the relationship between the back-reflection coefficient of Si3N4 waveguide and different tilt angles. The simulation result shows that when the end face of the Si3N4 waveguide is oblique cut by 15°, the back-reflection is the minimum, about -67 dB. The back-reflection obtained through the experiments are about -65 dB, consistent with the simulation result. Together, our data suggested that the back-reflection noise of the Si3N4 can be suppressed by the oblique cutting of the end face by 15°. The conclusion can lay a foundation for improving the performance of RIOG based on Si3N4 waveguide resonator.

Nowadays, a high level of security is required for the transmission of critical information. Quantum Key Distribution (QKD) systems are considered the best option to protect such information. Many studies have shown the efficiency of the QKD optical fiber inspired by M-ary pulse position modulation (MPPM). Free-Space Optical (FSO) links provide an efficient and effective data transmission system. However, cumulative effects of laser beam divergence, misalignment, and turbulence-induced fading on the received irradiance in the FSO link might allow an external eavesdropper located near the authorized receiver to break the transmission under certain conditions. This paper introduces the development of an FSO system based on the MPPM and the BB84 protocol (MPPM-BB84) over the Gamma-Gamma (GG) turbulence channel with pointing errors. Time Binning is implemented using MPPM to increase system security and reduce the quantum bit error rate (QBER). The system security is investigated under photon number splitting attack and excess noise. Closed-form expressions for asymptotic expressions of the average symbol error probability (SER), raw key rate (RKR), and secret key rate (SKR) are introduced. Moreover, the Monte-Carlo simulations are then used to prove the validity of the analytical results. The optimal values for the average photon number per pulse (to achieve the maximum RKR and SKR) for each symbol length can guarantee the stability of the FSO system under different weather conditions. Smaller symbol lengths are more tolerant of detector loss. The proposed system supports linking distances from 1 km to 3 km while keeping the SKR almost constant.

To overcome the severe losses beyond 28 GHz in low-cost electrical channels, 4-level pulse-amplitude modulation (4-PAM) wireline links targeting 112 Gb/s incorporate resource- or power-intensive equalization schemes such as decision-feedback equalizers (DFE) with many taps. Alleviating the timing constraints that cause DFEs to balloon in size and power, discrete multitone (DMT) modulation involves independent sub-channels that can be equalized in the frequency domain without feedback. DMT allows flexibility in assigning bits to each sub-channel, thereby potentially avoiding lossy parts of the frequency spectrum. This article presents behavioural modeling results and an experimental setup used to study DMT transceivers. Our simulations show 200 Gb/s operation at a bit error rate (BER) of less than ${10^{-5}}$ over an IEEE P802.3ck channel with 21 dB of loss at 50 GHz and assuming $150~\mathrm{fs_{rms}}$ of jitter, $1.26~{\mathrm{ mV}}_{\mathrm{ rms}}$ of noise at the receiver’s input, and 7-bit 80 GS/s data converters. An updated bit-loading algorithm led to BER values 1–2 orders of magnitude below our previous results. The estimated power and area of the associated digital signal processing are comparable to those of DFE. We also present an experimental DMT setup achieving 61.6 Gb/s at a BER of ${8.6 \times 10^{-4}}$ over a physical channel with severe notches that is very challenging for 4-PAM.

An 8-bit switched-capacitor multiply-and-accumulator (MAC) in 65nm CMOS is presented. Based on a cascaded low-power ring-amplifier-based switched-capacitor DACs, the MAC circuit features a programmable accumulation length in MAC computation. Fabricated in 65nm CMOS, the prototype MAC circuit achieves a precision-scaled energy efficiency of 1.32fJ per MAC operation, which is comparable to other state-of-the-art MAC circuits, along with best-in-class linearity. The noise performance has been verified using four real-world convolutional neural networks (CNNs) and 10,000-image data sets with up to 1,000 classes with an accuracy drop of less than 2% compared to the baseline 32-bit floating-point MAC.

The probability distribution of the signal-to-interference plus noise ratio (SINR) is analyzed and approximated by the generalized gamma distribution for mode-dependent loss (MDL)-impaired fiber links. Based on the characteristics of SINR, an improved reduced-search algorithm (IRS) based on multilevel SINR thresholding (IRS-MST) is proposed. IRS-MST dynamically determines the size of the search space for each mode based on multiple SINR thresholds. Furthermore, a compounding function is used to balance the size of the search space and performance. Simulation results show that IRS-MST can achieve near ML performance for different MDLs. Compared to the conventional IRS algorithm, the complexity of IRS-MST is approximately 5.4 times smaller than that of the IRS.

We propose a Modulated Retro-Reflector (MRR) based Physical-Layer Network Coding (PNC) framework for space two-way relay (TWR) optical communications. MRR PNC simplifies the end node’s design by replacing pointing, acquisition and tracking mechanisms which require large size, weight, and power (SWaP) consumption. Each end node modulates its data on top of the interrogating beam from the relay node so that the two end nodes’ frequencies are synchronized and there is no carrier frequency offset between the two end nodes and the relay. However, the transmitted signal based on the interrogating beam and twice the channel fading leads to noise aggregation. We analyze the impact of this noise aggregation by deriving the bit error rate (BER) for MRR PNC and performing simulations in Gamma-Gamma fading channels. The simulation results show that MRR PNC has a 3 dB optical signal noise ratio penalty compared with MRR “point-to-point” systems. The overall system throughput of MRR PNC is 99% higher than the traditional non-network-coded scheme in the ≥6 dB (for BPSK, ≥9 dB for QPSK) signal noise ratio regime. We propose using low-density parity-check (LDPC) codes to mitigate the problem of the degradation of the BER caused by the noise aggregation in MRR PNC. Our simulation results show that a rate 1/2 LDPC code can achieve 2 dB coding gain on BER 10−3. We show that the asynchrony penalty is 3 dB on BER 10−3 compared with a synchronous system. The implication is that when channel coding is used, the system can still work. Our findings show that MRR PNC can double the system throughput while keeping low values of SWaP, is feasible for space TWR optical communications.

We demonstrate a temperature-insensitive and high-sensitive label-free biosensor for low-concentration Human IgG detection based on S-tapered optical fiber (STF). The sensor is sensitive to local refractive index changes and has high robustness against temperature noise without a temperature control system. The temperature sensitivity of the sensor is −0.02nm/°C in the range of 25°C-45°C. Within 15 minutes at room temperature, the average drift of the center wavelength is 0.04 nm. The calibration experiments demonstrate that STFs for liquid achieved a sensing precision of 0.04 nm and a sensitivity of 538.62 nm/RIU. The STFs are applied for the concentration measurement of multiple diluted ex vivo IgG biomolecule solutions. The results showed that STFs were reliable for low-concentration IgG detection and its lower limit of measurement was demonstrated as 28 ng/ml. With the advantages of temperature-insensitive, compact size, low cost, high precision, real-time detection, fast response, good specificity, this STF sensors are promising for the antigen detection applications.

In this article, a spectral polarimetric filter named moving spectral depolarization ratio (MsDR) filter is proposed to mitigate the effects of clutter and noise for dual-polarization weather radar without cross-polar measurements. The filter is based on a spectral polarimetric variable termed as spectral depolarization ratio (sDR). sDR can be estimated by any polarimetric weather radar, making the MsDR filter widely applicable. Taking advantage of the spectral polarimetric features and the range-Doppler continuity of precipitation, the MsDR filter is implemented in the range-Doppler spectrogram. The performance of the MsDR filter is assessed using data collected by 1) an X-band full-polarimetric radar interfered by narrow-band clutter (both stationary and moving) and sidelobe wind turbine clutter; 2) a C-band operational dual-polarization radar affected by radio frequency interference. In addition, the implementation of the MsDR filter is straightforward, and the computational complexity is relatively low. Hence, the MsDR filter has great potential to be applied in real-time for operational radar systems at different frequencies.

In recent years, the serious vibration and noise problem of high voltage filter capacitor has become the primary problem of noise reduction in high voltage direct current (HVDC) converter station. The current research mainly focuses on the experimental measurement of the vibration and noise of the filter capacitor, without considering the influence of the residual charge on the dielectric interface stress. In this paper, the experimental platform is built for measuring the residual charge of the dielectric film in filter capacitor component, and the measurement results show that there are non-uniform residual charges on the dielectric surface of filter capacitor. In order to study the influence of uneven distribution of charge on dielectric interface stress, 12 different residual charge distributions are designed, and the results show that the uneven distribution of surface residual charge has a great influence on dielectric interface stress, and the higher uneven distribution of residual charge can cause the larger the stress on the dielectric surface of filter capacitor. The negative residual charge can lead to larger dielectric interface stress, which has a more serious impact on the vibration of filter capacitor component.

Quantum state tomography (QST) is the task of statistically constructing the density matrix of an unknown quantum state by measuring its several copies. The presence of noise in the QST setup can considerably degrade the fidelity between the constructed density matrix and the actual state. We consider a noisy QST setup with depolarizing noise and attempt to mitigate the effects of noise by quantum error mitigation (QEM). We compare the performance of different QEM methods with the same resources and find that the measurement error mitigation and zero noise extrapolation provide the best performance in terms of maximizing the fidelity between the state and its density matrix.

Synchronous phasor measurements have long been an important tool in power flow modelling and network state estimation as well as in many other tasks that support power grid observability. Classic phasor estimation algorithms are often preferred over complex alternatives. They are based on a variant of the Discrete Fourier Transform (DFT) while relying on a sampling frequency locked to the system nominal frequency. The spectral leakage caused by the small off-nominal frequency excursions in such settings introduces errors that are handled by the estimation algorithms to a different extent. Well-known three-point averaging filter (3P) is a low-cost spectral leakage reduction technique in one of the simplest estimators based on a single-bin DFT. However, it only partially removes the oscillating components. When an independent standard-based frequency tracking is available, the errors can be further compensated with minimal cost. We propose a frequency-corrected three-point estimator (F3P) to eliminate the induced spurious spectrum progressively with the increasing sampling rate while building on the analytical expression of the remaining error. We show performance benefits of the F3P under finite sampling rates when compared to the baseline 3P and to the classical Interpolated DFT (IPDFT) in static conditions. The F3P removes most of the leakage without the need of data resampling. In less ideal conditions with additive 50-dB noise, up to a 10-fold reduction of the 3P error is achieved. The error ratio of the reference IPDFT over the F3P is approximately 1.4 under the same conditions and largely independent of the frequency excursion. The presented simulation results prove the algorithm’s superior performance in most of the steady-state tests defined by the relevant Standard, whereas the dynamic performance can be brought to an acceptable level by the use of a single-cycle observation window, with the response times comparable to those of the IPDFT.

This paper presents design, mathematical analysis, and measurement of low noise single-stage transimpedance amplifier (TIA) with scalable bandwidth using 130 nm bipolar complementary metal-oxide-semiconductor (BiCMOS) silicon-germanium (SiGe) process. Common-emitter (CE) shunt-shunt feedback topology with active inductor peaking has been used in the design for improving noise, gain and driving capability of TIA by decreasing the input and output impedance, respectively. The use of active inductive peaking in CE shunt-shunt feedback topology has resulted in a new TIA configuration with better performance. The circuit has been optimized for low noise by adopting the proposed design technique. Validity of the mathematical analysis and design for the proposed TIA has been established with the help of simulations as well as measurement results. The measurement results of Ku-band TIA (10 MHz to 14 GHz) have demonstrated a transimpedance gain of $53.2~dB\Omega $ , input-referred current noise of 16.8 pA/ $\sqrt {Hz}$ with power consumption of $9.8~~mW $ . The design architecture is adaptable for higher frequency bands, which has been demonstrated by designing another TIA covering K- and Ka-bands (10 MHz to 35 GHz) with transimpedance gain of 33.4 dB $\Omega $ , input-referred current noise of 29.4 pA/ $\sqrt {Hz}$ with power consumption of $28.1~~mW $ in the post-layout simulation results, and occupies same chip area as that of 14 GHz, i.e., $0.1\times 0.21\,\,mm^{2}$

This paper proposes a cardiac electrogram acquisition and stimulation integrated circuit (IC) for single-chamber leadless pacemaker applications. The proposed IC features self-determining pacing by acquiring an intracardiac electrogram without an external digital signal processor (DSP). A novel current-feedback instrumentation amplifier (CFIA) is proposed to achieve high noise-power efficiency and high input impedance. In this proposed CFIA, the current-reused cascode differential-difference input stage and class-AB biasing stage are merged. The electrocardiogram (ECG) sensing channel, equipped with a 60-Hz notch filter to relieve powerline interference (PLI), achieves a power supply rejection ratio (PSRR) of 80 dB, a common-mode rejection ratio (CMRR) of 174 dB, and an input-referred noise of $3.47~\mu $ VRMS, in a 350 Hz bandwidth. The ECG acquisition and cardiac pacing functionality of the IC are evaluated in a swine’s right ventricle via a 4-electrode catheter.

We propose a scheme for deterministic remote preparation of an arbitrary two-qubit state via a relay node. Afterwards, we investigate how the scheme is influenced by the noise type, the initial state to be remotely prepared, and the decoherence rate. We find that the fidelity is symmetrical with the line (λb-f =λp-f =0.5) in bit-flip and phase-flip channels. In addition, the fidelity decreases with the increase of decoherence rate in the amplitude-damping and phase-damping channels. We also compare it with other RSP schemes. Since only Bell pairs work as the quantum channels, it makes our RSP scheme more available and feasible.

In the resonator fiber optic gyroscope (RFOG), both the residual intensity modulation (RIM)-induced error and backscattering-induced noise need to be effectively suppressed. When the clockwise and counterclockwise resonance detection adopt the same phase modulation and demodulation scheme, namely reciprocal detection, the reciprocity of the RFOG is improved, and the error induced by the RIM of the phase modulator used for detection (PMD) can be effectively suppressed. However, it is inevitable to add a phase modulator used for frequency shift (PMFS) to suppress the backscattering-induced noise. In this paper, the influence of the RIM of the PMFS on the performance of the RFOG is analyzed, and the model of the RIM-induced error in the RFOG with reciprocal detection is established. The analysis shows that in order to reduce the bias to the level of the shot noise, it is necessary to suppress the error induced by the RIM of the PMFS, and reducing the modulation frequency of the PMFS can effectively suppress the RIM-induced error. When a phase modulator is added to the RFOG with reciprocal detection to further suppress the backscattering-induced noise, the RIM-induced error can still be effectively suppressed by reducing the frequency of the added phase modulation.

High-Q microwave photonic filters may be realised with infinite impulse response (IIR) transfer functions, which are implemented typically with all-optical recirculating delay lines (RDL) operating in the incoherent regime. A key problem with these structures is phase-induced intensity noise (PIIN), which results in SNR degradation. Here we show that by using a hybrid optoelectronic loop instead of an all-optical loop for the RDL, it is possible to reduce the PIIN by up to 28 dB and to also achieve a higher finesse by letting the loop gain approach unity. The significance of the PIIN reduction is shown with the comparison of optoelectronic oscillators implemented with the all-optical RDL and the hybrid optoelectronic RDL, with the latter leading to a reduction in phase noise of 14 dB at 10 kHz frequency offset.

Optical networks-on-chips (ONoCs) are the key technology for the sustainable development of multiprocessors system-on-chip (MPSoC) in the future. Micro-ring resonators (MRs) are widely used in ONoCs as key device to select and redirect optical signals. However, MRs have the inherent property of being sensitive to environmental temperature. With the fluctuation of environmental temperature, its resonance wavelength drifts, which can introduce more loss and crosstalk noise to ONoCs and make the network performance decline sharply. Therefore, it is very important to analyze the influence of thermal effect in ONoCs to solve this problem. In this paper, the theoretical models of loss and crosstalk noise changing with temperature are established from device level to network level, respectively. And a series of network performances of mesh-based ONoCs caused by thermal effect are systematically modeled and analyzed employing formal methods. Finally, we conduct case studies for mesh-based ONoCs using optimized crossbar optical router and crux optical router to evaluate the proposed method. The simulation results show that the performance of mesh-based ONoCs declines with the increase of temperature, such as the decrease of optical signal-to-noise ratio (OSNR) and the increase of bit error rate (BER), which severely limits the network scalability. The formal analytical models provide a criterion for the performance analysis of thermal effect in ONoCs. In addition, the formal methods have high portability and scalability, and can provide technical support for future research work.

In this paper, we propose and demonstrate the effect of effective index on silicon waveguide thickness by using MODE solution. The effect of effective index variations is presented for two different fixed core height of 220nm and 200nm, and with each the core width was from 300nm to 600nm at the steps of 100nm for Transverse Electric (TE) and Transverse Magnetic (TM) mode. With the simulation results, the thickness of the core width is used for the determination of fundamental or higher order mode design. It is seen that higher effective index can be achieved as the core width and core height increases. The determination of fundamental or higher order mode design can be achieved by analysing the graphs of effective indices for TE0, TM0, TE1 and TM1 modes at varying core height and width. Based on the analysis, it is concluded that fundamental order can only be achieved when the silicon core width is kept at a value of approximately 500nm while higher mode order can be achieved if the silicon core width is kept more than 500nm. At a higher order mode, excess noise and losses can be introduced.

In this work we propose a variant of double-tail latched comparator, designed in 22 nm FDSOI (fully depleted silicon on insulator), operating at 2.88 GHz with supply voltage 0.8 V and achieving input referred offset and rms noise of 2.38 mV (1σ) and 33 µV, respectively in post-layout simulations. By modifying the timing control of the conventional double-tail comparator, the gain of the pre-amplifier is increased, thereby enhancing the speed, noise and offset parameters of the comparator.

Frequency generation is an important application in today’s radio frequency (RF) circuit design, especially for RF transceivers. The main challenges are to provide high spectral purity, while keeping the power consumption and area of the system low. In addition, with emerging mobile communication standards e.g. long term evolution (LTE) or 5G, various frequency bands and wide tuning ranges must be provided. This paper gives a brief overview of noise mechanisms, which have to be tackled, and a review of selected state-of-the-art frequency synthesizers (phase-locked-loops (PLLs)), as well as their limitations with respect to spectral purity. A novel interpretation of the figure-of-merit (FoM) for PLLs is shown emphasizing the impact of the resonators quality factor. In addition an outlook on possibilities to overcome the mentioned phase-noise limitations by using high quality factor (high-Q) RF-frequency generation circuit topologies utilizing e.g. surface-acoustic-wave- (SAW-), bulk-acoustic-wave- (BAW-) or micro-electro-mechanical-systems- (MEMS-) resonators.

Performance of a Li-ion battery is affected by temperature; low temperature causes reduced power output and high temperature affects state of health and compromises safety. To overcome these challenges and for reliable performance of batteries, thermal management is needed in electric vehicles. This paper presents a thermal-electrical equivalent circuit model to predict the surface temperature of a battery. Three algorithms are presented for the estimation of thermal-electrical equivalent model parameters. These algorithms are based on least square, constrained least squares, and weighted least squares respectively. It is shown that the performance of a battery thermal model parameter estimation approach can suffer from measurement noise. The performance of the algorithms are compared using computer simulations at various signal-to-noise levels. It is found that the weighted least squares based approach outperforms the other two approaches in parameter estimation accuracy.

This paper presents a novel self-commissioning procedure for the identification of inverter nonlinearity constant comprised of the average voltage drops on switches and diodes in conduction state and switching delays. Simultaneous estimation of phase resistance, d-axis synchronous inductance, and inverter nonlinearity constant is achieved at standstill condition by injecting sinusoidal d-axis current. The advantages of the proposed self-commissioning method are twofold: 1) The co-estimation capability provides insensitivity towards errors in resistance and d-axis inductance. 2) While sinusoidal d-axis current is injected, the q-axis current is actively maintained at 0A. Thus, no torque is generated during the self-commissioning period. The effect of discontinuous distortions due to non-ideal switching as well as current sensor noise is rejected by limiting the estimation period within a feasible estimation window. Thereby, a necessary minimum phase current magnitude is established for achieving accurate estimation. This paper also provides parameter convergence analysis and the existence of unique solutions during proposed self-commissioning process, further justifying the choice of proposed feasible estimation region.

At present, Solid State Power Controller (SSPC) integrated with short-circuit protection function is gradually replacing the traditional mechanical protection device and playing an important role in airborne fuel cell system (FCS). SSPC can quickly isolate short-circuit faults and avoid damage to FCS. However, the response of traditional SSPC is still slow for short-circuit protection, leading to a large fault current. In this paper, a bidirectional DC SSPC for airborne proton exchange membrane fuel cell systems (PEMFC) is proposed. This SSPC adopts a protection scheme based on the current rising rate, which is implemented with high-speed analog devices. Its simulation verification in the power supply system for a fuel-cell-powered unmanned aerial vehicle (UAV) is provided with Simulink. The results show that the protection speed of the scheme is considerably faster than the traditional protection scheme based on the current amplitude. Also, a circuit-level simulation is performed in Saber to show other advantages of the scheme, such as low energy consumption, allowing capacitive load, immunity to noise interference, and the effectiveness of FCS protection.

In this paper, we explore the effect of practical channel conditions on the achievable secrecy of reconfigurable intelligent surface (RIS)-aided multiple-input single-output (MISO) wireless communications with the existence of both the legitimate (Bob) and the eavesdropper (Eve) nodes. Specifically, by considering beamforming at the source (Alice), we study the practical scenario where Alice has Bob's channel state information (CSI); however, she doesn't know Eve's CSI. (i.e., passive eavesdropping case). To this end, we first derive approximate expressions for modeling the RIS cascaded channel applying the Maximum Likelihood (ML) algorithm. This approach allows for incorporating relevant factors into RIS's channel modeling, including phase shift noise, correlation between RIS elements, and coexistence or not of the direct links at both the legitimate and eavesdropper nodes. Based on these findings, we obtain a closed-form solution of the outage secrecy probability for the underlying system. Finally, some valuable insights on how various channel features and the number of RIS elements affect the secrecy behavior are also presented.

This paper explores PCB winding coupled inductor design for a SiC-based critical conduction mode soft-switching three-phase ac-dc converter with balance technique. Although using SiC devices with the soft-switching technique can achieve high power density and efficiency, high dv/dt over the system parasitic capacitance causes substantial common mode (CM) noise compared to Si devices. To reduce the CM noise, a balance technique is applied to the three-phase ac-dc converter creating a return path and adding inductors in the path. The inductors in the main circuit and the return path are coupled in one core and implemented with the PCB windings to enhance the CM noise reduction capability. A new PCB winding structure is introduced to minimize the winding loss and to have strong coupling between the main and additional inductors. Design considerations and the design process of the PCB winding coupled inductor are discussed in detail. The performance of the soft-switching three-phase acdc converter with the proposed PCB winding coupled inductor is experimentally verified with a SiC-based 25-kW laboratory prototype.

3-level T-type neutral point clamped (NPC) topology is more popular than its 2-level counterparts in energy conversion systems due to their higher efficiency, lower harmonics (THD), and reduced voltage stress on the switches. Wide bandgap (WBG) semiconductors have become the ultimate choice for future high-performance power electronics energy conversion due to their superior material properties compared to traditional silicon power devices. As a wide-bandgap device, while SiC’s faster-switching speed improves overall efficiency by reducing switching loss, the faster voltage and current gradient (dv/dt and di/dt) generate electromagnetic interference (EMI) noise, requiring larger and complicated filter design. A stacked DBC (direct bonded copper) based T-type NPC power module has been proposed, designed, and tested where additional DBC will be acting as an EMI shield. The EMI noise propagation path has been modeled and compared to a traditional power module. A 21 dB reduction of CM (common mode) noise has been observed.

GaN HEMTs permit fast switching, leading to high dV/dt being generated across them. The Common Mode (CM) noise associated with the dV/dt propagates through the gate drivers’ isolation barrier capacitance. Due impedance mismatch between the PWM signal line and return, CM to Differential Mode (DM) noise transformation occurs and distorts the PWM signal at the input of gate driver. This paper investigates the impact of high dV/dt induced noise on gate drive performance in GaN systems. Firstly, noise propagation paths and CM to DM noise transformation are analyzed, followed by simulation and Double Pulse Test (DPT) on hardware. The results show that noise distortion causes mis-triggering of the switches. Further, it is proposed that a cascaded stage comprising power supply and gate driver can suppress the noise by increasing the noise path impedance. The proposed method is verified on hardware with turn-off and turn-on dV/dt equal to 88 V/ns and 62 V/ns respectively at 400 V without mis-triggering.

Due to high efficiency and bidirectional capability, unregulated CLLC converters have significant potential for the DC transformer and chargers with two stages, where the switching frequency is designed to be fixed at resonance. However, the actual resonant frequency may drift from the designed value because of resonant tank component tolerances, temperature, and aging. This leads to a decrease in efficiency for unregulated CLLC converters with a fixed frequency. To solve these issues, a bidirectional resonant frequency tracking method is proposed for CLLC converters in this paper. Based on the analysis of input and output impedance, a unique feature is discovered that no matter how resonant tank parameters deviate, the switching frequencies harvesting maximum efficiency are identical for bidirectional operations. To track this global optimal switching frequency, the proposed method adopts a voltage edges-based sensing technique, so the bidirectional tracking is realized and costly current sensors of conventional methods are eliminated. It is lower cost and robust against noise. Experimental results show that bidirectional fast-tracking and efficiency improvement are achieved for parameter deviation conditions.

Unbalanced magnetic forces have been identified as one of the main causes of noise and vibration in small permanent magnet machines. Dynamic and static eccentricity as well as nonuniform magnetization are known as the dominant sources of the aforementioned forces. This paper analyzes the effect of the interaction of these different types of manufacturing imperfections on the unbalanced radial forces, focusing particularly on their phase difference. It shows the wide range of resulting distributions of the magnetic force that significantly exceeds those of the single-effect analyses. This explains the widespread structure-borne noise observed with sub-fractional HP machines, also reflected in extensive experimental investigations. The analyses also explore how dynamic eccentricity can counteract nonuniform magnetization and vice versa.

A miniature Fourier transform spectrometer is designed with tailored optical path differences for visible spectral reconstruction. The combination of intelligent algorithms, the convex optimization algorithm (CVX) and the one-dimension modified convolutional neural network (Unet), is used to retrieve spectra under measurement with noise. This scheme recovers four kinds of spectra accurately with the mean-square error of 8.32 × 10−4.

A method based on a constellation diagram is proposed to identify QAM modulation of different orders in static, slow, and frequency selective fading channels. Although constellation diagrams have been studied and classified in literature, most of the work focused on noise. Little has been done to study the effect of multipath fading channels. We develop a highly accurate modulation classification method by exploiting deep learning with the constellation diagram. Based on the experimental results, our CNN model achieves a classification accuracy of 100% at −10 dB signal-to-noise ratio (SNR) under a multipath Rayleigh fading channel.

The paper presents a dual low voltage chopper offset-stabilized operational amplifier with symmetrical RC notch filters, having a 1.6-5.5 V supply range, and being fabricated in a 0.25 µm CMOS process. The chopping frequency is 100 kHz. A new constant-gm technique is implemented within the input stage of main amp, improving most electrical performances. The amplifier has a typical offset voltage of 1 µV, a minimum PSRR of 128 dB, a minimum CMRR of 120 dB, a noise PSD of 42 nV/√Hz, 1.5 MHz unity gain bandwidth, and THD + noise of 0.001 % at 1 kHz, while consuming 70 µA per channel.

Chemiresistive sensor technologies can detect chemical trace in the air down to the low Part Per Billion (ppb)/Part Per Trillion (ppt) level. Achieving such low detection levels requires low-noise and high-accuracy analog front-end interfaces. One such interface uses a Sigma Delta $(\Sigma\triangle)$ Analog to Digital Converter (ADC) topology that leads to lower noise at low frequency and better effective resolution. The slow charging dynamics of chemicals in the environment is well-suited for $\Sigma\triangle$ converters. While $\Sigma\triangle$ converters are a well-studied topic, the potential resolution of chemical sensing using chemiresistive sensors has not yet been demonstrated in a fully integrated mixed-signal interface. In this paper, we develop a $\Sigma\triangle$ architecture combined with a 10-pA resolution Digitally Controlled Current Sources (DCCS) and an integrated Proportional Integrator Derivative (PID) controller feedback loop. The PID drives back the current sources at 250 kHz to maintain a constant voltage across the sensor, acting as a variable resistor Implemented on a 180 nm CMOS process with an 8-bits current source resolution at 250 kHz and coupled with nanofiber chemiresistive sensors, it translates into lppb level detection. Compared to the state-of-the-art chemical sensing interface, our circuit shows a 5$\times$improvement in detection level and a $ 10\times$ improvement in power efficiency, given the same detection level.

Inverter-based low-noise amplifier (LNA) offers an elegant solution in terms of power and area efficiency, which is favorable for ultrasound receivers. Nevertheless, it imposes challenges on circuit designs regarding the biasing circuit, the limited gain, robustness over process, supply voltage and temperature (PVT) variations. This paper presents an in-depth study of various inverter-based LNAs for ultrasound receiver design. In addition, three fully differential inverter-based LNAs are designed and optimized with minimum power and area penalty in the common-mode feedback (CMFB) circuit. The LNAs are implemented in a standard 0.18 - $\mu m$ CMOS process, with the identical power consumption, simulation results show that LNA with single CMFB achieves lower distortion, i.e. a third harmonic distortion (HD3) of $\lt -51.5$ dB with 35 mVp-p input, LNA with dual CMFB obtains better noise performance, i.e. $4.85 nV / \sqrt{Hz}$ at 3 MHz.

For the first time, RIN reduction in gain-switched quantum dot laser is demonstrated with an optical beam illumination to the excited state. It is also found that pulses having a width of 27–29 ps with a high peak power are generated under the noise.

This is a case study of the variational quantum eigensolver (VQE) method using numerical simulations to test the influence of noise on the accuracy of the underlying circuit ansatz. We investigate a computational chemistry application of VQE to calculate the electronic ground state and its energy for Sodium Hydride (NaH), a prototypical two-electron problem. Using a one-parameter ansatz derived from unitary coupled cluster (UCC) theory, we simulate the effects of noise on the energy expectation value and variance with respect to the ansatz parameter. These numerical simulations provide insights into the accuracy of the prepared quantum state and the efficiency of the classical optimizer that iteratively refines the ansatz. We conduct a comparative study between analytical results derived for the UCC ansatz in the absence of noise and the noisy numerical simulation results obtained using an isotropic depolarizing noise model for each gate. We also compare the relative increase in noise on logically equivalent UCC ansatz circuits generated by randomized compiling. Notably, we observe that the intrinsic variance in the energy due to the simplicity of the ansatz itself compares with the noise induced by the bare circuit.

This paper proposes a parallel photonic architecture for computing dense dot products, such as those found during deep neural network (DNN) inference, and quantifies the architecture's computation error induced by crosstalk and noise.

Untethered channel sounders are used to measure mobile radio propagation channels. As high data rate, millimeter-wave and multiple-input multiple output (MIMO) are considered in the next generation communications systems, knowledge of the propagation channel needs to be studied in high accuracy. Measuring time stability of the clocks in both transmitter and receiver is essential when characterizing relative delay between multipath components (MPCs), absolute delay, angle of arrival (AoA) and angle of departure (AoD) of MPCs. This paper describes timing circuit design of untethered electronic switched MIMO millimeter-wave channel sounders, proposes practical method to remove a constant initial time error, and experimentally estimates time stability of the channel sounders. Time stability is classified in three categories: short-term (in order of microseconds) that impacts relative delay, AoA and AoD; medium-term (in order of minutes) that impacts absolute delay; and long-term stability (in order of days) that can be calibrated. This is the first time to apply standard parameters for measuring clock stability, such as timing Allan deviation (TDEV) and time interval error (TIE), to channel sounding and modeling. Novel methods are developed for measuring jitter and short-term noise. It was found that TDEV for short-term measurements was less than 1 ps and the medium-term timing errors due to clock noise could be maintained at 0.4 ns/min.