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ABSTRACT A variable gain amplifier (VGA) is an essential building block used in the automatic gain control (AGC) loop to provide a continuous, adjustable gain for the signal strength. To maintain the stability and consistency of the AGC loop, it is necessary to ensure that the gain of the VGA has an accurate dB‐linear characteristic. This tutorial provides a detailed overview of the development of dB‐linear VGAs based on differential pair structures over recent years. We categorize various VGA cells based on differential pair structures, analyze their operating principles, and explain the key features of each topology. Based on observation and extraction of the dB‐linear implementation schemes used by these VGAs, we summarize three basic methods for achieving dB‐linear gain control. We also discuss specific methods for realizing the exponential function, using a true exponential and a mathematical approximation, and present the different types of approximation functions adopted in the works described here. Considerations in regard to the tuning range, gain error, bandwidth, linearity, process‐temperature robustness, and circuit simplicity are also discussed. Finally, we draw comparisons and give perspectives for future dB‐linear VGAs. [ABSTRACT FROM AUTHOR]

We present a high‐speed burst‐mode optical receiver operating at 25‐Gb/s with the shortest reconfiguration time of 4.52‐ns reported up to date. The receiver consists of a burst‐mode trans‐impedance amplifier (TIA) with 1/8‐rate clock‐assisted DC offset cancellation loop as well as automatic gain control loop, and a burst‐mode clock‐data recovery (CDR) with two‐stage injection‐locking architecture. Both designed and fabricated in a 28‐nm CMOS process, the TIA + CDR optical receiver consumes 101‐mW from a 0.9‐V supply. With a continuous‐time linear equalizer, series inductive peaking and shunt inductive peaking, the 3‐dB bandwidth of ZT(O‐E) of TIA is 20 GHz with 14‐dB gain dynamic range (45–59 dB). The sensitivity of the burst‐mode receiver is −10.1 dBm at BER = 1E‐12. [ABSTRACT FROM AUTHOR]

In this paper, a novel digital closed-loop interface circuit system of MEMS vibrating gyroscope is proposed, which includes driving, detection and quadrature circuits. Because of the high sensitivity and precision of the MEMS gyroscope, the interface circuit system is established under the condition of mode separation. The driving circuit of MEMS gyroscope adopts digital automatic gain control (AGC) to realize self-excitation closed-loop control, which makes the gyroscope system simple in structure and good in robustness. First, the working principle of the gyroscope's sensitive structure is introduced and the system simulation model of the sensitive structure is developed. Second, a Σ Δ ADC and DAC with single-bit output are designed and the feasibility of the driving circuit design is verified by the system-level model. Third, the quadrature closed-loop correction circuit is designed to reduce the coupling of the quadrature component to the gyroscope detection circuit. The simulation results show that the quadrature correction loop can effectively reduce the influence of the quadrature coupling on the detection loop of MEMS gyroscope. Finally, the system-level model of the gyroscope is established by SIMULINK, the overall system performance of the gyroscope is analyzed, and the test system of MEMS gyroscope is built by field-programmable gate array (FPGA) and application specific integrated circuit (ASIC). The experiment verifies the feasibility of the digital interface circuit design, and the zero-bias instability of the gyroscope system is 1.0∘/h. [ABSTRACT FROM AUTHOR]

Angular velocity is a very important measurement parameter for autonomous driving and industrial applications. The design of MEMS quartz gyro measurement and control circuit has always been the key to restricting the measurement angular velocity performance of gyro system. This paper introduces the application-specific integrated circuit (ASIC) design and implementation of a MEMS quartz gyro measurement and control circuit for angular velocity measurement. The designed nonlinear multiplier can use a square wave to drive the gyro's sensitive structure at the beginning of gyro start-up, thereby reducing the gyro power-up time. The drive circuit replaces the PLL with an automatic gain control unit composed of peak detection and proportional integration (PI) controller, which makes the MEMS gyro system have good robustness. First, SIMULINK is used to model and simulate the MEMS gyroscope system-level model, which illustrates the feasibility of the drive circuit design scheme. Then, the operating principle of the drive loop is analyzed, and the design of the key circuit modules of the measurement and control circuit is introduced. Finally, the performance of the gyroscope drive and detection circuit is experimentally tested, the amplitude and frequency uncertainty of the gyroscope drive circuit are evaluated, and the bias instability and nonlinearity of the gyroscope are tested, the experiment results show that the gyroscope has good performance. [ABSTRACT FROM AUTHOR]

AbstractObjectiveDesignStudy sampleResultsConclusionsOne proposed method to improve sound localisation for bilateral cochlear implant (BiCI) users is to synchronise the automatic gain control (AGC) of both audio processors. In this study we tested whether AGC synchronisation in a dual-loop front-end processing scheme with a 3:1 compression ratio improves sound localisation acuity.Source identification in the frontal hemifield was tested in in an anechoic chamber as a function of (roving) presentation level. Three different methods of AGC synchronisation were compared to the standard unsynchronised approach. Both root mean square error (RMSE) and signed bias were calculated to evaluate sound localisation in the horizontal plane.Six BiCI users.None of the three AGC synchronisation methods yielded significant improvements in either localisation error or bias, neither across presentation levels nor for individual presentation levels. For synchronised AGC, the pooled mean (standard deviation) localisation error of the three synchronisation methods was 24.7 (5.8) degrees RMSE, for unsynchronised AGC it was 27.4 (7.5) degrees. The localisation bias was 5.1 (5.5) degrees for synchronised AGC and 5.0 (3.8) for unsynchronised.These findings do not support the hypothesis that the tested AGC synchronisation configurations improves localisation acuity in bilateral users of MED-EL cochlear implants. [ABSTRACT FROM AUTHOR]

Bioimpedance is a diagnostic sensing method used in medical applications, ranging from body composition assessment to detecting skin cancer. Commonly, discrete-component (and at times integrated) circuit variants of the Howland Current Source (HCS) topology are employed for injection of an AC current. Ideally, its amplitude should remain within 1% of its nominal value across a frequency range, and that nominal value should be programmable. However, the method's applicability and accuracy are hindered due to the current amplitude diminishing at frequencies above 100 kHz, with very few designs accomplishing 1 MHz, and only at a single nominal amplitude. This paper presents the design and implementation of an adaptive current source for bioimpedance applications employing automatic gain control (AGC). The "Adaptive Howland Current Source" (AHCS) was experimentally tested, and the results indicate that the design can achieve less than 1% amplitude error for both 1 mA and 100 µA currents for bandwidths up to 3 MHz. Simulations also indicate that the system can be designed to achieve up to 19% noise reduction relative to the most common HCS design. AHCS addresses the need for high bandwidth AC current sources in bioimpedance spectroscopy, offering automatic output current compensation without constant recalibration. The novel structure of AHCS proves crucial in applications requiring higher β-dispersion frequencies exceeding 1 MHz, where greater penetration depths and better cell status assessment can be achieved, e.g., in the detection of skin or breast cancer. [ABSTRACT FROM AUTHOR]

In this paper, a signal model and a mathematical analysis of an efficient approach are derived to acquire the approximate magnitude of a complex signal by inducing a pre-biased or a pre-scaled factor in the design criteria. According to the deductive results, the pre-biased or pre-scaled factor can be 2∼3 dB, which is determined through its application. The numerical evaluations show that the mean square error (MSE) of the proposed efficient approach for the random signal is around −33 dB. Based on the design templates for the considered approaches, the occupied areas of the proposed type-1 and -2 approaches are merely 0.13 and 0.09 times the area of the direct-method, respectively. As a result, the proposed efficient approach is certainly a cost-efficient method for obtaining the approximate magnitude of a complex signal. [ABSTRACT FROM AUTHOR]

A fully differential lumped linear driver for Mach–Zehnder modulator has been presented and assessed in 130‐nm SiGe BiCMOS technology. Multitopology peaking techniques, especially T‐coil peaking method, have been employed to flatten the frequency response and increase the bandwidth. Degeneration resistors have been used to enhance circuit linearity. Simultaneously, improvements have been made to the output stage of the conventional single emitter follower push–pull) circuit to enhance the output eye diagram quality at higher transmission rates. The fabricated driver achieved a differential gain of 16.2 dB with a bandwidth of over 50 GHz, corresponding to a fixed output swing of over 3.2 Vppd within the automatic gain control loop. Time domain measurements, limited in speed by the measurement setup, reported a data rate up to 56 Gb/s none return to zero and 40‐GBaud 4‐levels pulse amplitude modulation with a bit error rate less than 10−12. [ABSTRACT FROM AUTHOR]

Abstract The first 30 min of the aftershock sequence following the 2022 September 17, ML 6.4, Guanshan, Taiwan earthquake is investigated by the back-projection (BP) method. Based on the Automatic Gain Control (AGC) to process individual earthquake record and sort waveforms by epicentral distance, 80 events are identified near the Guanshan earthquake epicenter to verify its temporal variation. However, most of these events cannot clearly image by the BP method to determine its spatial locations for its small amplitude and short time separation. In total, 29 aftershocks are imaged by this study to identify its spatial locations during this time period. The relocated events are compared with the Central Weather Bureau (CWB) rapid report catalogue. Only 5 events have been reported by the CWB rapid report catalogue. These unreported hidden aftershocks are identified to distribute surrounding the epicenter and extended to the east. This extracted information of hidden aftershocks is crucial for assessing the potential for future large aftershocks and estimating the associated seismic hazards in a given region, and provide extra message to evaluate the source physics in general.

The first 30 min of the aftershock sequence following the 2022 September 17, ML 6.4, Guanshan, Taiwan earthquake is investigated by the back-projection (BP) method. Based on the Automatic Gain Control (AGC) to process individual earthquake record and sort waveforms by epicentral distance, 80 events are identified near the Guanshan earthquake epicenter to verify its temporal variation. However, most of these events cannot clearly image by the BP method to determine its spatial locations for its small amplitude and short time separation. In total, 29 aftershocks are imaged by this study to identify its spatial locations during this time period. The relocated events are compared with the Central Weather Bureau (CWB) rapid report catalogue. Only 5 events have been reported by the CWB rapid report catalogue. These unreported hidden aftershocks are identified to distribute surrounding the epicenter and extended to the east. This extracted information of hidden aftershocks is crucial for assessing the potential for future large aftershocks and estimating the associated seismic hazards in a given region, and provide extra message to evaluate the source physics in general. Key Points: Propose and verify earthquake location using the back-projection method. Discover 29 hidden events with 30 min after the Guanshan earthquake. Provide extra information to study following large aftershocks and to estimate its associated seismic hazards. [ABSTRACT FROM AUTHOR]

Abstract Key parameters of analog‐to‐digital converters (ADCs) are their sampling rate and dynamic range. Power consumption and cost of an ADC are directly proportional to the sampling rate; hence, it is desirable to keep it as low as possible. The dynamic range of an ADC also plays an important role, and ideally, it should be greater than the signal's; otherwise, the signal will be clipped. To avoid clipping, modulo folding can be used before sampling, followed by an unfolding algorithm to recover the true signal. Here, the authors present a modulo hardware prototype that can be used before sampling to avoid clipping. The authors’ modulo hardware operates prior to the sampling mechanism and can fold higher frequency signals compared to existing hardware. The authors present a detailed design of the hardware and also address key issues that arise during implementation. In terms of applications, the authors show the reconstruction of finite‐rate‐of‐innovation signals, which are beyond the dynamic range of the ADC. The authors’ system operates at six times below the Nyquist rate of the signal and can accommodate eight times larger signals than the ADC's dynamic range.

Tracking systems for wireless power transfer are becoming a necessity. The received target signals are sometimes weak, which is why it is critical to have a dedicated received–signal–strength indicator (RSSI) for signal detection. It can also be used for transmitter localization and automatic gain control (AGC) to ensure continuous coverage. In this paper, a logarithmic detector coupled with a high-speed full-wave rectifier is designed for an RSSI system. The aim is to place the RSSI on the receiver side of unmanned aerial vehicles used, for example, as agricultural drones. This system is intended to operate in a scenario where multiple drones in a smart farm are charged wirelessly whilst airborne. An RSSI is placed in the receiver to detect and track wireless signals and to ensure the drone is charged while in motion. The RSSI system operates at 5.8 GHz, reported for the first time, and is capable of detecting signal strengths from −60 dBm to 0 dBm with a sensitivity level of 17 mV/dBm. A logarithmic error of 0.4 dB with a dynamic range of 34 dB was achieved. The proposed RSSI system was designed using 65 nm TSMC CMOS technology, and it exhibits high sensitivity, better efficiency, and lower power consumption than those in other reported works. [ABSTRACT FROM AUTHOR]

The article focuses on the development of HAVOC, a deep neural network pipeline, to create "Histomic Atlases of Variation Of Cancers." HAVOC aims to provide spatially contextualized estimates of biodiversity in tumor specimens, addressing challenges in resolving cancer heterogeneity across large tissue specimens. This approach leverages histopathological features to objectively define cytoarchitectural variations using computer vision strategies.

Automatic gain control (AGC) filters are commonly applied to potential field data to produce images where both large and small amplitude features become prominent. These filters are usually based on ratios of the derivatives (or Hilbert transforms) of the data and are sensitive to noise as a result. By exploiting the fact that the data has an amplitude and phase component it is possible to produce an edge-enhanced dataset with minimal noise issues. The filters are demonstrated on synthetic data and on datasets from South Africa. [ABSTRACT FROM AUTHOR]

A fully integrated low-power area-efficient receiver using a low–intermediate frequency topology for BDS-3 and GPS L1 bands is presented in this paper. Accurate localization can be achieved without requiring off-chip low-noise amplifiers. The receiver bandwidths for GPS and BDS-3 are 2 MHz and 4 MHz, respectively. Digitally assisted calibration schemes, such as RC calibration, automatic gain control, and DC offset correction are integrated to resist the effects of the process, voltage, and temperature (PVT) variations. The receiver—fabricated in a standard 55 nm CMOS technology—provides a maximum gain of 113.2 dB, a gain control range of 61 dB, and a minimum noise figure of 1.74 dB under a 1.2 V supply. The receiver, with and without the frequency synthesizer that provides the local oscillator frequency, consumes 8.7 mA and 4.8 mA, with areas of 0.73 mm2 and 0.345 mm2, respectively. [ABSTRACT FROM AUTHOR]

Chronic diseases, specifically Cardiovascular Disease (CVD), pose a substantial worldwide health obstacle, requiring innovative and comprehensive approaches to management. This study presents an innovative method for managing chronic diseases by combining Federated Learning (FL) and the Internet of Things (IoT). The goal is to offer tailored healthcare solutions. The study presents a new approach called Federated Transfer Learning (FTL) that incorporates Adaptive Gradient Clipping (AGC) to improve the performance of models and maintain privacy in a distributed network of healthcare devices. The primary objective of this study is to develop a holistic framework that seamlessly amalgamates data from various sources, including wearables, medical devices, and electronic health records, utilizing FL to build a centralized model while preserving data privacy at the individual level. The proposed Faster Than Light (FTL) algorithm with Automatic Gain Control (AGC) enhances the process of model convergence, guaranteeing stability and dependability in a federated learning environment. The research methodology entails implementing the suggested framework in the management of Cardiovascular Disease (CVD). The performance of the model is assessed using the Area Under the Curve (AUC) metric, resulting in an impressive AUC score of 92.4%. This highlights the efficacy of the integrated approach in precisely forecasting and controlling risks associated with cardiovascular diseases (CVD), showcasing its potential for widespread use in managing chronic diseases. The key findings emphasize the advantages of integrating IoT devices into the FL ecosystem, enabling the immediate surveillance and gathering of various health data. The decentralized nature of the learning process enables model training to occur without compromising data privacy, making it suitable for large-scale healthcare systems. Moreover, the implementation of Faster Than Light (FTL) with Automatic Gain Control (AGC) improves the resilience and effectiveness of the federated learning procedure, thereby enhancing the overall achievement of the suggested framework. In conclusion, this study presents a groundbreaking contribution to the field of chronic disease management, specifically targeting Cardiovascular Disease. The combination of Federated Learning and IoT, along with the innovative Federated Transfer Learning with Adaptive Gradient Clipping, not only achieves outstanding predictive accuracy but also guarantees the privacy and security of sensitive health data. The proposed framework holds significant promise for revolutionizing personalized healthcare solutions, paving the way for a more effective and patient-centric approach to chronic disease management. [ABSTRACT FROM AUTHOR]

The article provides information about connexin-mediated intercellular signaling, which is involved in various physiological and pathological processes. It particularly focuses on Connexin 32 (Cx32) and its significance in the peripheral nervous system, where mutations in Cx32 are linked to Charcot-Marie-Tooth disease (CMT1X), a neuromuscular disorder.

In ground penetrating radar (GPR) surveys of African‐American cemeteries suspected to contain unmarked graves, determining the proficiency of a new GPR practitioner is vital and perhaps even more fundamental than that of the GPR hardware, deployment configuration and software. Proficiency may be defined as the practitioner's true‐positive, true‐negative, false‐positive (i.e., false alarms) and false‐negative (i.e., misses) percentages. We embarked on this research as a means to improve our own proficiency in unmarked grave detection and to develop an algorithm by which to improve the proficiency of any new GPR practitioner. After surveying the Salem Cemetery in Brazos County, TX, and the Old Danville‐Shepherd Hill Cemetery in Montgomery County, TX, we first classified subsurface targets based on in‐field, visual inspection of the real‐time, onscreen, unprocessed (except for an automatic gain control) GPR B‐scans. We then developed a proxy for ground‐truthing that allowed us to calculate the proficiency of the in‐field classifications. From this proxy, we established a quantitative prevalence threshold for identifying or rejecting a subsurface object as a target of interest. Its quantitative nature allowed us to quantitatively control and adjust that threshold, a threshold we set at 70% likely to be to a specific target of interest. We show that our classification accuracy increased from 66.2% at the Salem Cemetery to 75.0% at the Old Danville‐Shepherd Hill Cemetery and, through use of diagnostic evaluations originally developed for medical imaging and herein applied to geophysics, showed that the accuracy improved due to increases in true‐negative classifications, that is, in examining real‐time, onscreen, mostly unprocessed GPR B‐scans, discerning a potential target and correctly concluding it was not an unmarked grave. This research outlines the procedure we developed to measure the proficiency of a new GPR practitioner. [ABSTRACT FROM AUTHOR]

Key parameters of analog‐to‐digital converters (ADCs) are their sampling rate and dynamic range. Power consumption and cost of an ADC are directly proportional to the sampling rate; hence, it is desirable to keep it as low as possible. The dynamic range of an ADC also plays an important role, and ideally, it should be greater than the signal's; otherwise, the signal will be clipped. To avoid clipping, modulo folding can be used before sampling, followed by an unfolding algorithm to recover the true signal. Here, the authors present a modulo hardware prototype that can be used before sampling to avoid clipping. The authors' modulo hardware operates prior to the sampling mechanism and can fold higher frequency signals compared to existing hardware. The authors present a detailed design of the hardware and also address key issues that arise during implementation. In terms of applications, the authors show the reconstruction of finite‐rate‐of‐innovation signals, which are beyond the dynamic range of the ADC. The authors' system operates at six times below the Nyquist rate of the signal and can accommodate eight times larger signals than the ADC's dynamic range. [ABSTRACT FROM AUTHOR]

The collection of profile data is standard practice within the field of mass spectrometry (MS). However, profile data collection often results in large data files that require extensive processing times, especially in mass spectrometry imaging (MSI) studies where thousands of high-resolution scans are recorded. Natively collecting centroid MS data is an alternative that effectively reduces both the resulting file size and the data processing time. Herein, high-resolution accurate mass (HRAM) Orbitrap MSI data on mouse liver tissue sections without automatic gain control (AGC) were natively collected in both profile and centroid modes and compared based on the file size and processing time. Additionally, centroid data were evaluated against the profile data with regard to the spectra integrity, mass measurement accuracy (MMA), and the number of lipid annotations to ensure that centroid data did not compromise the data quality. For both native and postacquisition centroided data, the variation in mass measurement accuracy decreased relative to the profile data collection. Furthermore, centroid data collection increased the number of METASPACE database annotations indicating higher sensitivity and greater accuracy for lipid annotation compared to native profile data collection. Profile MSI data was shown to have a higher likelihood of false positive identifications due to an increased number of data points on either side of the peaks, whereas the same trend was not observed in data collected in native centroid data collection. This publication explores and explains the importance in properly centroiding MSI data, either natively or by adequate centroiding methods, to obtain the most accurate information and come to the best conclusions. These data support that natively collecting centroid data significantly improves MMA to sub-ppm levels without AGC and reduces false positive annotations. [ABSTRACT FROM AUTHOR]

The article discusses about plasticity-induced adaptation during standard-of-care chemotherapy temozolomide (TMZ). It further discusses about in vivo single-cell RNA sequencing in patient-derived xenograft (PDX) tumors of glioblastoma (GBM) before, during, and after therapy; dGTP and dCTP production vital for DNA damage response during TMZ therapy; and strong correlations between ribonucleotide reductase regulatory subunit M2 (RRM2) and deoxyguanosine triphosphate (dGTP).

Ultrasonic communication and power transfer are attractive solutions when conventional electromagnetic-based or wired connections are unfeasible. Most ultrasonic communication applications concern a single-solid barrier. Nevertheless, some relevant scenarios can be composed of several fluid—solid media, through which communication and power transfer are intended. Due to its multi-layer nature, insertion loss and, consequently, the system efficiency considerably decrease. This paper presents an ultrasonic system capable of simultaneously power transferring and transmitting data through a set of two flat steel plates separated by a fluid layer using a pair of co-axially aligned piezoelectric transducers on opposite sides of the barrier. The system is based on frequency modulation and adopts a novel technique for automatic gain and automatic carrier control. The modems used herein were developed specifically for this application, rendering the system able to transfer data at a rate of 19,200 bps, using the frequency shift keying (FSK) modulation scheme and simultaneously transferring 66 mW of power through two flat steel plates (5 mm) separated by a fluid layer (100 mm), which completely supplied a pressure and temperature sensor. The proposed automatic gain control allowed a higher data transmission rate and the automatic carrier control reduced power consumption. The former reduced the transmission error from 12% to 5%, while the latter reduced the global power consumption from 2.6 W to 1.2 W. The proposed system is promising for monitoring applications such as oil wellbore structural health monitoring systems. [ABSTRACT FROM AUTHOR]

Purpose: In this investigation, a linear encoder system based on the ultrasonic transducer has been proposed. Ultrasonic transducers are usually designed for distance measurements, such as the time of flight method and sonar system. These applications are defined as discrete-length measurement technologies. The purpose of this study is to develop a continuous displacement measurement system using ultrasonic transducers. Design/methodology/approach: A modified signal processing based on heterodyne signaling is implemented in this system. In the proposed signal processing, there is an automatic gain control module, a phase-shifting module, a phase detection module, an interpolation module and especially a frequency multiplication module, which can enhance the resolution and reduce the interpolation error simultaneously. Findings: The proposed system can generate the encoding signals and is compatible with most motion control systems. For the experimental result, the maximum measurement error and standard deviation are about −0.027 and 0.048 mm, respectively. It shows that the proposed encoder system has the potential for displacement measurement tasks. Originality/value: This study reveals an ultrasonic linear encoder that is capable of generating an incremental encoding signal, accompanied by a corresponding signal processing methodology. In contrast to the conventional heterodyne signal processing approach, the proposed multiplication method effectively reduces the interpolation error that arises because of multiple reflections. [ABSTRACT FROM AUTHOR]

Objectives: Global positioning system (GPS) block IIR and block IIF satellites have the capabili‑ ty to redistribute the power of their transmitted signals between individual signal components. One or more GPS signals upon designated area can be adjusted or even shut off as needed. The analysis of GPS signals is of great importance for both ground and space uses. FengYun-3D (FY-3D) satellite is one of China’s polar orbiting meteorological satellites. We try to help GPS users comprehensively understand the charac‑ teristic of GPS flex power based on real measurement data of FY-3D satellite. Methods: The global coverage of FY-3D satellite is used to analyze the strength of GPS signals, especially the characteristics of the signal change during GPS flex power period. The characteristics of global interference of L band is also researched by using the in-orbit data. And the interference on the automatic gain control and base noise of occultation antenna of global navigation satellite system occultation sounder is reported. Results: The re‑ sults show that the GPS flex power, which started on February 14, 2020, is centered on [35°N，37°E] and [35°N，69°E], and its radius is about 7 500 km. The GPS P(Y) code is increased by about 10 dB in this re‑ gion. The interference of GPS L1 band and L2 band are continuously affected by interference in the Middle East. The base noise in this region is increased about 3—10 times compared with other areas. The centre point of interference and the centre point of GPS flex power is roughly in the same place. Conclusions: GPS flex power and interference have a significant impact on GPS users, especially on the positioning of low earth orbit satellites, which should be taken into account in the design of GNSS receivers. [ABSTRACT FROM AUTHOR]

We report for the first time an implementable method to identify and suppress the driving force misalignment angle for a MEMS gyroscope working either in amplitude modulated (AM) or Lissajous frequency modulated (LFM) mode using parametric excitation. By introducing driving force misalignment angle into gyroscope dynamic equations, we illustrate that gyroscope angular rate output is affected by driving force misalignment angle and cross-axis damping jointly. We propose parametric excitation as a way to both identify and calculate the driving force misalignment angle. The identification results for a gyroscope working in both AM and LFM mode are similar, which indicates the effectiveness of the proposed identification method. Instead of using traditional amplitude control loop by adjusting the driving force, we do the automatic gain control by adjusting the parametric pump voltage so that a fixed drive voltage can be used, which also indicates fixed force coupling. Experimental results show that after suppression, the bias instability (BI) of AM mode is improved from 4.7° h−1 to 2.3° h−1 and the BI of LFM mode is improved from 1.4° h−1 to 0.9° h−1 which is the lowest result reported for LFM gyroscope. [ABSTRACT FROM AUTHOR]

This article establishes a circuit model with which to analyze the difficulty of auto-gain control driving for low-Q micromechanical gyroscopes at room temperature and normal pressure. It also proposes a driving circuit based on frequency modulation to eliminate the same-frequency coupling between the drive signal and displacement signal using a second harmonic demodulation circuit. The results of the simulation indicate that a closed-loop driving circuit system based on the frequency modulation principle can be established within 200 ms with a stable average frequency of 4504 Hz and a frequency deviation of 1 Hz. After the system was stabilized, the root mean square of the simulation data was taken, and the frequency jitter was 0.0221 Hz. [ABSTRACT FROM AUTHOR]

A variable attenuator is one of the essential components in radio frequency (RF) systems, such as automatic gain control amplifiers and full-duplex systems. Variable attenuators based on microelectromechanical systems (MEMS) technology have several advantages over the semiconductor counterparts, including low power consumption and suppressed harmonics. Attenuation can be realized by disruption of signal propagation, which is induced by moving electrodes placed next to a signal line. In this work, the effect of the moving electrodes on the RF characteristics of the variable attenuators is studied via numerical simulation. It is observed that 10 μ m of moving electrode displacement can result in 18 dB of attenuation dynamic range at 20 GHz. The similar type of RF MEMS variable attenuators reported previously showed substantial nonlinearity in attenuation-voltage characteristics, which becomes a serious drawback for applications where high-precision attenuation management is required. The main objective of the current study is, therefore, to achieve high dB-linearity, by employing shaped-finger comb-drive actuators in the moving electrode displacement control. In addition, a nonlinear relationship between force and displacement in a clamped-clamped beam spring is taken into account for more accurate device modelling. Through finite element analysis, it is shown that an improvement by a factor of twelve can be obtained in dB-linearity by using a single-comb shaped-finger actuator, compared to standard straight-finger comb-drives. The study also shows that the dB-linearity can be further (2.2 times additionally) improved by utilizing dual-comb shaped-finger actuators. [ABSTRACT FROM AUTHOR]

Laser interferometry of the space gravitational wave antenna needs to demodulate the gravitational wave signal by a phasemeter with high phase readout precision. A phasemeter in digital phase locking loop structure was proved to be sensitive to the amplitude fluctuation of the input signal experimentally in previous studies. In this work, we have carried out theoretical analysis on the influence of amplitude fluctuation on phase readout precision. The results show that amplitude noise belongs to multiplicative noise, which cannot be eliminated by differential measurement. We used the automatic gain control (AGC) circuit to suppress the fluctuation of amplitude. Contrast experiments were performed to verify that the AGC circuit could promote the performance of the phasemeter system for gravitational wave detection. [ABSTRACT FROM AUTHOR]

For a camera with automatic gain control, two images with high and low optical gain can be output at the same exposure time. Due to the small gain value, most of target details are hidden in the dark pixels for the low gain image, and the brightness saturation usually appears in high gain image for the high luminance areas. To obtain the essential information from the dual gain images, a generation method of high dynamic range image based on dual gain image was developed. The method is composed of five parts, including enhancement of image detail, establishment of Laplacian pyramid, selection of fusion operator, reconstruction of fusion pyramid and adjustment of image contrast. Results showed that combination of the gradient operator for N-1 layer and the neighbourhood filter operator for the Nth layer had better fusion effect. Moreover, based on the analysis of image information entropy and clarity, the fusion efficiency was calculated, and the fusion efficiency of Mertens's method, Jiang's method, Zhang's method, Goshtasby's method and the presented method was 30.5%, 33.5%, 39.5%, 51% and 99%, indicating that the HDR fusion method based on dual gain image is reliable. [ABSTRACT FROM AUTHOR]

This paper presents the design of an automatic gain control (AGC) loop for high‐speed communication systems, which can be used in wired, wireless, or optical receiver. The design is performed in 130 nm SiGe BiCMOS technology. A Gilbert cell‐based variable gain amplifier is designed, which shows approximately linear gain control with respect to the gain control voltage. The variable gain amplifier is followed by two fixed gain cascode amplifiers. Then, a full wave rectifier‐based peak detector is designed and analyzed. To reduce the peak detector error, a compensation technique is applied. Finally, an operational amplifier is designed, which is used as voltage adder and comparator. The designed AGC loop is simulated with sinusoidal and pseudorandom binary sequence (prbs) input signal with high frequency signal of 1 to 30 GHz. The simulation results of the AGC loop show that a gain tuning range of 47 dB (−7 to 40 dB) is obtained in this design. It is also seen that the reference signal can be varied from 50 to 200 mV. This AGC works in the input voltage signal range between 3 mV peak and 230 mV peak, and the power dissipation of is 79 mW. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a low-cost, expansible, and compatible measurement and control system for atomic force microscopes (AFM) based on a quartz tuning fork (QTF) self-sensing probe and frequency modulation, which is mainly composed of an embedded control system and a probe system. The embedded control system is based on a dual-core OMAPL138 microprocessor (DSP + ARM) equipped with 16 channels of a 16-bit high-precision general analog-to-digital converter (ADC) and a 16-bit high-precision general digital-to-analog converter (DAC), six channels of an analog-to-digital converter with a second-order anti-aliasing filter, four channels of a direct digital frequency synthesizer (DDS), a digital input and output (DIO) interface, and other peripherals. The uniqueness of the system hardware lies in the design of a high-precision and low-noise digital—analog hybrid lock-in amplifier (LIA), which is used to detect and track the frequency and phase of the QTF probe response signal. In terms of the system software, a software difference frequency detection method based on a digital signal processor (DSP) is implemented to detect the frequency change caused by the force gradient between the tip and the sample, and the relative error of frequency measurement is less than 3%. For the probe system, a self-sensing probe controller, including an automatic gain control (AGC) self-excitation circuit, is designed for a homemade balanced QTF self-sensing probe with a high quality factor (Q value) in an atmospheric environment. We measured the quality factor (Q value) of the balanced QTF self-sensing probes with different lengths of tungsten tips and successfully realized AFM topography imaging with a tungsten-tip QTF probe 3 mm in length. The results show that the QTF-based self-sensing probe and the developed AFM measurement and control system can obtain high quality surface topography scanning images in an atmospheric environment. [ABSTRACT FROM AUTHOR]

Radio waves and strong magnetic fields are used by Magnetic Resonance Imaging (MRI) scanners to detect tumours, wounds and visualize detailed images of the human body. Wi-Fi and other medical devices placed in the MRI procedure room produces RF noise in MRI Images. The RF noise is the result of electromagnetic emissions produced by Wi-Fi and other medical devices that interfere with the operation of the MRI scanner. Existing techniques for RF noise mitigation involve RF shielding techniques which induce eddy currents that affect the MRI image quality. RF shielding techniques are complex and lead to RF leakage. VLC (Visible light Communication) is an emerging and efficient technology to avoid RF interference near MRI scanners. Range augmentation with power conservation of the LED is a big challenge in existing VLC systems. The major objective of the proposed work is to develop an intelligent-MRI room design without RF interference using visible light communication and enhance the distance between VLC transmitter and VLC receiver. In this paper, it is proposed to implement VLC using On-Off keying modulation and enhance distance using large active area photodiodes with Automatic Gain Control Circuit (AGC) using software and hardware. The performance of the proposed intelligent MRI-VLC system is analyzed by calculating Bit Error Rate at an inclined distance of 50 cm away from line of sight of the LED. The Experimental results showed that the maximum distance achieved was 400 cm at Bit Error Rate (BER) of 1.5 × 10−5 . [ABSTRACT FROM AUTHOR]

The article presents a study which explores that deep top-down proteomics (TDP) has revealed significant proteoform-level differences between metastatic and nonmetastatic colorectal cancer cells. It mentions that study represents a pivotal advance in TDP toward the characterization of human proteome in a proteoform-specific manner, which will transform basic and translational biomedical research.

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This paper presents a 5.8 GHz highly sensitive, high-dynamic-range RF receiver front-end with Automatic-Gain Control (AGC) and a high image-rejection for a Dedicated Short-Range Communication (DSRC) application. It is formed by a transceiver common matching, a single to differential Low-Noise Amplifier (LNA), an active mixer with an Image Rejection Filter, and an AGC unit. The proposed AGC unit is composed of a power-detector over the intermediate-frequency signals of the downconverter mixer. The power detector produces a wide dynamic range response signal, which eases the controllability of the AGC unit. In addition, external components are minimized, and area occupation is optimized. The proposed RF-FE is fabricated and measured in a 130-nm RF CMOS process. Experimental results show an overall dynamic range of 77.6 dB while a high sensitivity performance to an input power level of −85 dBm is measured. An overall gain of 26.4 dB for the RF-FE is obtained. The input referred P1dB is measured to be around −28.3 dBm. The 2-stage RC poly-phase filter that is applied to reject the image signal results in a maximum image rejection ratio of 39 dB.

Featured Application: This work presents common-mode driven synchronous filtering (SF) of powerline interference (PLI) by a software demodulator-remodulator concept. SF is shown to be robust against deviations in PLI amplitude, frequency, and phase with calibration and physiologic ECG signals. The presented SF algorithm is generalizable to different biopotential acquisition settings via surface electrodes (electroencephalogram, electromyogram, electrooculogram, etc.) and can benefit many diagnostic and therapeutic medical devices. Powerline interference (PLI) is a major disturbing factor in ground-free biopotential acquisition systems. PLI produces both common-mode and differential input voltages. The first is suppressed by a high common-mode rejection ratio of bioamplifiers. However, the differential PLI component evoked by the imbalance of electrode impedances is amplified together with the diagnostic differential biosignal. Therefore, PLI filtering is always demanded and commonly managed by analog or digital band-rejection filters. In electrocardiography (ECG), PLI filters are not ideal, inducing QRS and ST distortions as a transient reaction to steep slopes, or PLI remains when its amplitude varies and PLI frequency deviates from the notch. This study aims to minimize the filter errors in wide deviation ranges of PLI amplitudes and frequencies, introducing a novel biopotential readout circuit with a software PLI demodulator–remodulator concept for synchronous processing of both differential-mode and common-mode signals. A closed-loop digital synchronous filtering (SF) algorithm is designed to subtract a PLI estimation from the differential-mode input in real time. The PLI estimation branch connected to the SF output includes four stages: (i) prefilter and QRS limiter; (ii) quadrature demodulator of the output PLI using a common-mode driven reference; (iii) two servo loops for low-pass filtering and the integration of in-phase and quadrature errors; (iv) quadrature remodulator for synthesis of the estimated PLI using the common-mode signal as a carrier frequency. A simulation study of artificially generated PLI sinusoids with frequency deviations (48–52 Hz, slew rate 0.01–0.1 Hz/s) and amplitude deviations (root mean square (r.m.s.) 50–1000 μV, slew rate 10–200 μV/s) is conducted for the optimization of SF servo loop settings with artificial signals from the CTS-ECG calibration database (10 s, 1 lead) as well as for the SF algorithm test with 40 low-noise recordings from the Physionet PTB Diagnostic ECG database (10 s, 12 leads) and CTS-ECG analytical database (10 s, 8 leads). The statistical study for the PLI frequencies (48–52 Hz, slew rate ≤ 0.1 Hz/s) and amplitudes (≤1000 μV r.m.s., slew rate ≤ 40 μV/s) show that maximal SF errors do not exceed 15 μV for any record and any lead, which satisfies the standard requirements for a peak ringing noise of < 25 μV. The signal-to-noise ratio improvement reaches 57–60 dB. SF is shown to be robust against phase shifts between differential- and common-mode PLI. Although validated for ECG signals, the presented SF algorithm is generalizable to different biopotential acquisition settings via surface electrodes (electroencephalogram, electromyogram, electrooculogram, etc.) and can benefit many diagnostic and therapeutic medical devices. [ABSTRACT FROM AUTHOR]

This article presents a neural-recording IC with automatic gain control (AGC) according to the input signal level. AGC enhances the dynamic range (DR) of the recording IC by more than 30 dB and allows it to take the benefits of the front-end amplification-based and direct-conversion-based recording structures concurrently. By adaptively controlling the analog front-end (AFE) gain, the input-referred noise (IRN) of the overall system is greatly reduced while ensuring a wide DR. A continuous-time (CT) dynamic-zoom $\Delta \Sigma $ ADC (CT-Zoom-ADC) is used for power-efficient two-step conversion. The coarse conversion output is reused for AGC, and the fine conversion resolution is adjusted adaptively by modifying the oversampling ratio according to the varying AFE gain. The presented neural-recording IC achieves 99.5-dB DR and 6.1- $\mu \text{V}_{\textrm {rms}}$ IRN over 5-kHz bandwidth, resulting in FoMDR of 185.2 dB, the effective number of bits (ENOB) of 11.4 bits, and tolerance against artifacts with differential voltage amplitudes up to 1.6 $\text{V}_{\text {pp}}$. Measurements with pulsatile artifacts and experiments in vivo validate that the proposed IC is applicable to the closed-loop neural interface. [ABSTRACT FROM AUTHOR]

Free space optical (FSO) communication is coming up as an attractive alternative to solve the connectivity hindrances. It is an efficient optical technology having several advantages such as narrow beam size, unlicensed spectrum, high reliability, huge modulation bandwidth, low power and higher grade of security. In this paper, we have proposed an FSO communication system model using EDFA-EDFA hybrid optical amplifier (HOA) configuration which provides enhanced reach and higher data rate. For transmitting channel, weak turbulence approximation which exhibits log-normal statistics is considered. Q-factor, bit error rate (BER) and Eye diagram have been taken as performance metrics. From simulative results, it has been observed that the designed FSO communication system efficiently enhances the transmission reach from 1,000 to 5,000 m along with a substantial improvement in Q-factor and BER. [ABSTRACT FROM AUTHOR]