Bandwidth Calibration Research Articles

SPATIAL REGRESSION APPROACH TO MODELLING POVERTY IN JAVA ISLAND 2022

Geographically Weighted Regression (GWR) model is a powerful tool for analyzing spatial patterns in data. However, the standard form of a spatial model that uses a single bandwidth calibration may be unrealistic because the response-predictor relationship may be either linear or nonlinear. To address this issue, the Multiscale GWR (MSGWR) model offers improved model performance by employing Generalized Additive Model (GAM) with varying bandwidth or smoothing function for each covariate in the model. This research aims to analyze the Percentage of Poor Population (PPP) on Java Island in 2022 using the geospatial models and related socioeconomic and demographic attributes, such as Open Unemployment Rate, Human Development Index, Labor Force Participation Rate, and GRDP Per capita to identify the best model in explaining the spatial pattern and to find out the determinant of PPP on Java Island in 2022. This study uses secondary data from Statistics Indonesia. The findings reveal that the MSGWR model provides the highest R2 and smallest AICc value compared to single bandwidth models, specifically the GWR and MXGWR models. Furthermore, the MSGWR model indicates that HDI has a significant negative effect on PPP, whereas LFPR has a significant positive effect on PPP across all districts in Java Island in 2022.

Calibration of Raman Bandwidths on the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Deep Ultraviolet Raman and Fluorescence Instrument Aboard the Perseverance Rover.

In this work, we derive a simple method for calibrating Raman bandwidths for the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument onboard NASA's Perseverance rover. Raman bandwidths and shapes reported by an instrument contain contributions from both the intrinsic Raman band (IRB) and instrumental artifacts. To directly correlate bandwidth to sample properties and to compare bandwidths across instruments, the IRB width needs to be separated from instrumental effects. Here, we use the ubiquitous bandwidth calibration method of modeling the observed Raman bands as a convolution of a Lorentzian IRB and a Gaussian instrument slit function. Using calibration target data, we calculate that SHERLOC has a slit function width of 34.1 cm-1. With a measure of the instrument slit function, we can deconvolve the IRB from the observed band, providing the width of the Raman band unobscured by instrumental artifact. We present the correlation between observed Raman bandwidth and intrinsic Raman bandwidth in table form for the quick estimation of SHERLOC Raman intrinsic bandwidths. We discuss the limitations of using this model to calibrate Raman bandwidth and derive a quantitative method for calculating the errors associated with the calibration. We demonstrate the utility of this method of bandwidth calibration by examining the intrinsic bandwidths of SHERLOC sulfate spectra and by modeling the SHERLOC spectrum of olivine.

Calibration of the temporal drift in absolute and relative Raman intensities in large Raman images using a mercury–argon lamp

AbstractRaman imaging is a powerful tool for the analysis of astromaterials including meteorites, cosmic dust, and samples returned to Earth by spacecraft. Many astromaterials are heterogeneous on mm‐ or cm‐sized scales requiring the collection of large Raman images with long accumulation times of days to weeks. It is known that the wavenumber and bandwidth calibration of a Raman instrument drifts with time and temperature resulting in significant changes in the observed Raman band over the course of Raman image collection. In this work, we examine the temporal and thermal drift of absolute and relative Raman intensities through the collection of a Raman image. We show that the spectrometer throughput and observed Raman intensities change over time and are correlated to small changes in lab temperature. We propose a method of calibrating for the drift in Raman intensities using a Hg–Ar (mercury–argon) calibration lamp integrated into the Raman instrument. We also show that relative Raman intensities drift with time as a function of temperature as a result of changes to the Raman instrument response function. We developed a method to calibrate the drifting instrument response function using only the calibration lines from the Hg–Ar lamp. Overall, our results elucidate the effects of temporal/thermal drift on Raman intensities and we propose calibration techniques to account for these effects.

A Type-I PLL With Foreground Loop Bandwidth Calibration

A 2.4 GHz type-I phase-locked loop with foreground loop bandwidth calibration is presented. A successive approximation method is presented to calibrate the loop bandwidth by digitally adjusting the switch size of the master-slave sampling filter. This brief is fabricated in 45 nm CMOS technology. Its active area is 0.013 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The power consumption is 3.6 mW at 2.4 GHz for a supply of 0.9 V. The integrated jitter over 1 kHz to 100 MHz is 3.6 ps. With the supply voltage of 0.88V~0.92V, the variation of the loop bandwidth is reduced from 18.7% to 4.6% by using the loop bandwidth calibration.

A 2.4–3.0GHz Process-Tolerant Sub-Sampling PLL With Loop Bandwidth Calibration

A sub-sampling phase-locked loop (SSPLL) with loop bandwidth calibration is presented. By using a sub-sampling phase detector with gain calibration and a pulse width control circuit, the loop bandwidth deviation of the SSPLL can be reduced. This SSPLL is fabricated in a 40 nm CMOS process and its core area is 0.15mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The power consumption of the SSPLL is 5.81mW from a supply of 1.1V. The reference frequency is 75 MHz and the output frequency range of the SSPLL is 2.4~3.0GHz. The measured rms jitter is 2.02ps at the output frequency of 3.0GHz. With the calibration, the largest loop bandwidth deviation from 3.5MHz among five samples is reduced from -71.4% to -18.5% at 3.0GHz.

A Bandwidth and Frequency Calibration Method for OOK UWB-IR Transmitter with High Energy Efficiency

In this paper, an offline bandwidth and frequency calibration method for an on–off LC oscillator-based ultra-wideband impulse radio (UWB-IR) transmitter is presented. Implemented in 0.18-[Formula: see text]m CMOS, the offline calibration circuits consume very little power. This allows the transmitter to consume an ultra-low average power of 319[Formula: see text][Formula: see text]W over 3–5[Formula: see text]GHz at 2[Formula: see text]Mbps. The calibration is critical to ensure the FCC spectral mask compliance despite the process–voltage–temperature (PVT) variations. The transmitter can deliver a large differential output swing of 1.8–3[Formula: see text]V to a 100-[Formula: see text] load with minimal power efficiency of 7% at different data rates (2–30[Formula: see text]Mbps). It is suitable for WPAN application with localization and positioning capabilities.

A Fully Integrated Bluetooth Low-Energy Transceiver with Integrated Single Pole Double Throw and Power Management Unit for IoT Sensors.

This paper presents a low power Gaussian Frequency-Shift Keying (GFSK) transceiver (TRX) with high efficiency power management unit and integrated Single-Pole Double-Throw switch for Bluetooth low energy application. Receiver (RX) is implemented with the RF front-end with an inductor-less low-noise transconductance amplifier and 25% duty-cycle current-driven passive mixers, and low-IF baseband analog with a complex Band Pass Filter(BPF). A transmitter (TX) employs an analog phase-locked loop (PLL) with one-point GFSK modulation and class-D digital Power Amplifier (PA) to reduce current consumption. In the analog PLL, low power Voltage Controlled Oscillator (VCO) is designed and the automatic bandwidth calibration is proposed to optimize bandwidth, settling time, and phase noise by adjusting the charge pump current, VCO gain, and resistor and capacitor values of the loop filter. The Analog Digital Converter (ADC) adopts straightforward architecture to reduce current consumption. The DC-DC buck converter operates by automatically selecting an optimum mode among triple modes, Pulse Width Modulation (PWM), Pulse Frequency Modulation (PFM), and retention, depending on load current. The TRX is implemented using 1P6M 55-nm Complementary Metal–Oxide–Semiconductor (CMOS) technology and the die area is 1.79 mm2. TRX consumes 5 mW on RX and 6 mW on the TX when PA is 0-dBm. Measured sensitivity of RX is −95 dBm at 2.44 GHz. Efficiency of the DC-DC buck converter is over 89% when the load current is higher than 2.5 mA in the PWM mode. Quiescent current consumption is 400 nA from a supply voltage of 3 V in the retention mode.

Hyper-local geographically weighted regression: extending GWR through local model selection and local bandwidth optimization

Geographically weighted regression (GWR) is an inherently exploratory technique for examining process non-stationarity in data relationships. This paper develops and applies a hyper-local GWR which extends such investigations further. The hyper-local GWR simultaneously optimizes both local model selection (which covariates to include in each local regression) and local kernel bandwidth specification (how much data should be included locally). These are evaluated using a measure of model fit. The hyper-local GWR approach evaluates different kernel bandwidths at each location and selects the most parsimonious local regression model. By allowing models and bandwidths to vary locally, this approach extends and refines the one-size-fits-all "whole map model" and "constant bandwidth calibration" under standard GWR. The results provide an alternative, complementary and more nuanced interpretation of localized regression. The method is illustrated using a case study modeling soil total nitrogen (STN) and soil total phosphorus (STP) from data collected at 689 locations in a watershed in Northern China. The analysis compares linear regression, standard GWR, and hyper-local GWR models of STN and STP and highlights the different locations at which covariates are identified as significant predictors of STN and STP by the different GWR approaches and the spatial variation in bandwidths. The hyper-local GWR results indicate that the STN processes are more non-stationary and localized than found via a standard application of GWR. By contrast, the results for STP are more confirmatory (i.e., similar) between the two GWR approaches providing extra assurance about the nature of the moderate non-stationary relationships observed. That is, a standard GWR may underestimate localized spatial heterogeneity where it is strongly present (as in the STN case study) and may overestimate it where spatial homogeneity is present (as in the STP case study). The overall benefits of hyper-local GWR are discussed, particularly in the context of the original investigative aims of GWR. A hyper-local approach provides a useful counter view of local regression modeling to that found with standard GWR. Where spatial non-stationarity exists, the hyper-local GWR provides a more spatially nuanced indication of the localization than a standard GWR analysis and can be used to suggest the direction of further analyses and investigations. Some areas of further work are suggested.

A constant loop bandwidth in delta sigma fractional-N PLL frequency synthesizer with phase noise cancellation

This work presents the design of a new and unique design technique of constant loop bandwidth and phase-noise cancellation in a wideband ΔΣ fractional-N PLL frequency synthesizer. Phase noise performance of the proposed ΔΣ fractional-N PLL frequency synthesizer has been verified using CppSim simulator with the help of transistor level simulation results in Cadence SpecctreRF. Transient response of the proposed ΔΣ fractional-N PLL has been verified in transistor level simulation using Cadence SpectreRF in 0.13 μm standard CMOS process. The proposed phase-noise cancellation and constant loop bandwidth in wideband ΔΣ fractional-N PLL reduces the out of band phase noise by 18 dBc/Hz at 2 MHz offset frequency for a closed loop bandwidth of 1 MHz, when ICP,max is equal to 2.6 mA. PLL locking time has been reduced with phase-noise cancellation and a constant loop bandwidth calibration circuits using the proposed CP unit current cell for the mismatch compensated PFD/DAC in wideband ΔΣ fractional-N PLL frequency synthesizer. Optimum phase noise performance can be achieved with the help of proposed design technique. Proposed ΔΣ fractional-N PLL frequency synthesizer is locked within 14.0 μs with an automatic frequency control circuit of the LC VCO and a constant loop bandwidth calibration circuit through the use of proposed CP unit current cell for the mismatch compensated PFD/DAC for the phase-noise cancellation in worst case condition of KVFC = 10 and KLBC = 150. Our new design technique can be extensively integrated for wideband fractional-N PLL for new type of wireless communication paradigm using the thinnest channel subharmonic transistor and low power devices, and it has the potential to open a new era of fractional-N PLLs for wideband application.

Phase noise analysis of proposed PFD and CP switching circuit and its advantages over various PFD/CP switching circuits in phase-locked loops

This paper presents the design of a new phase frequency detector (PFD) and different type of charge pump (CP) circuits for phase-locked loops. A proposed phase frequency detector circuit can eliminate the effect of missing edge and phase ambiguity problems in many PFDs. A novel CP circuit with a special switching scheme has been incorporated to reduce the current mismatch error, charge injection error and clock feed through effect in many CP circuits using a new and unique clocking scheme of up delay (UPD) and down bar-delay (DNBD) signals in place of the conventional UPD and DNB clock pulses. Output noise, input referred phase noise, and phase noise performance (with 10 fF load capacitance) of the proposed PFD and true single phase clock (TSPC) PFD have been studied with different CP circuits. The effect of CP current mismatch and DC offset current at any of the current source or sink has been incorporated to check the effect on spur and phase noise performance of the ΔΣ fractional-N PLL frequency synthesizer. In addition, PFD and charge pump circuit phase noise estimation theory has been illustrated and it has been verified through the transistor level simulation. PLL locking response has been verified through the transistor level simulation in Cadence SpectreRF for the different CPs configuration with the proposed PFD and it shows that the proposed PFD and different CP circuits lock much faster than other works in literature. This condition also holds for the automatic frequency control unit along with the loop bandwidth calibration circuit and in special case of both loop bandwidth calibration and phase noise cancellation circuit. According to our knowledge this work shows a new state of the art performances for this proposed charge pump circuit and phase noise analysis of the charge pump circuit in presence of an error amplifier and many switching circuits.

A Clock and Data Recovery Circuit with Adaptive Loop Bandwidth Calibration and Idle Power Saved Frequency Acquisition

This paper presents a clock and data recovery circuit with an adaptive loop bandwidth calibration scheme and the idle power saved frequency acquisition. The loop bandwidth calibration adaptively controls injection currents of the main loop with a trimmable bandgap reference circuit and trains the VCO to operate in the linear frequency control range. For stand-by power reduction of the phase detector, a clock gating circuit blocks 8-phase clock signals from the VCO and cuts off the current paths of current mode D-flip flops and latches during the frequency acquisition. 77.96% reduction has been accomplished in idle power consumption of the phase detector. In the jitter experiment, the proposed scheme reduces the jitter tolerance variation from 0.45-UI to 0.2-UI at 1-MHz as compared with the conventional circuit.

Adaptive Mean Shift-Based Identification of Individual Trees Using Airborne LiDAR Data

Identifying individual trees and delineating their canopy structures from the forest point clouddataacquiredbyanairborneLiDAR(LightDetectionAndRanging)hassignificantimplications in forestry inventory. Once accurately identified, tree structural attributes such as tree height, crown diameter, canopy based height and diameter at breast height can be derived. This paper focuses on a novel computationally efficient method to adaptively calibrate the kernel bandwidth of a computational scheme based on mean shift—a non-parametric probability density-based clustering technique—to segment the 3D (three-dimensional) forest point clouds and identify individual tree crowns. The basic concept of this method is to partition the 3D space over each test plot into small vertical units (irregular columns containing 3D spatial features from one or more trees) first, by using a fixed bandwidth mean shift procedure and a small square grouping technique, and then rough estimation of crown sizes for distinct trees within a unit, based on an original 2D (two-dimensional) incremental grid projection technique, is applied to provide a basis for dynamical calibration of the kernel bandwidth for an adaptive mean shift procedure performed in each partition. The adaptive mean shift-based scheme, which incorporates our proposed bandwidth calibration method, is validated on 10 test plots of a dense, multi-layered evergreen broad-leaved forest located in South China. Experimental results reveal that this approach can work effectively and when compared to the conventional point-based approaches (e.g., region growing, k-means clustering, fixed bandwidth or multi-scale mean shift), its accuracies are relatively high: it detects 86 percent of the trees (“recall”) and 92 percent of the identified trees are correct (“precision”), showing good potential for use in the area of forest inventory.

A fast and efficient constant loop bandwidth with proposed PFD and pulse swallow divider circuit in [formula omitted] fractional-N PLL frequency synthesizer

This work presents the design of a ΔΣ fractional-N PLL frequency synthesizer with a new loop bandwidth calibration and automatic frequency control (AFC) circuit, applicable for wide band RF communication system. This new and unique loop bandwidth calibration circuit has been implemented using logarithmic and anti-logarithmic (Base2) architecture. This architecture is an efficient design technique as well as faster operation in CMOS domain. The operating frequency range of the ΔΣ fractional-N PLL frequency synthesizer is from 2.158 to 5.133GHz. The variation of LC VCO gain (KVCO) is obvious due to wide band application and it varies from 30.65MHz/Volt to 368MHz/Volt for the frequency range of 2.158–5.133GHz. Constant loop bandwidth is maintained by controlling the charge pump current. Power consumption of the ΔΣ fractional-N PLL frequency synthesizer is 34mW from a 1.2Volt power supply and the work has been carried out in 0.13μm standard CMOS process. Also, this design includes an automatic frequency control unit for the LC VCO circuit which is coarsely tuned within 1.825μs for KVFC=10 for worst case condition and it completes the loop bandwidth (LBW) calibration within 7.84μs for KLBC=150 for worst case condition. The maximum locking time of the ΔΣ fractional-N PLL frequency synthesizer with loop bandwidth calibration and automatic frequency control circuit is 12.7μs for KVFC=10 and KLBC=150 for worst case condition. The ΔΣ fractional-N PLL is locked much faster than any work reported earlier using the proposed PFD, CP, proposed pulse swallow divider, efficient AFC circuit for LC VCO and a new loop BW calibration technique in transistor level simulation using Cadence SpectreRF. The main advantage of this loop bandwidth calibration technique is that the calibration time can be adjusted according to the PLL output frequency, loop bandwidth calibration accuracy and tuning frequency range of the LC VCO.

A CMOS Delta-Sigma PLL Transmitter with Efficient Modulation Bandwidth Calibration

A delta-sigma $(\Delta\Sigma)$ phase locked loop (PLL) transmitter with an efficient modulation bandwidth calibration technique is proposed in this paper. With the proposed technique, the digital-analog mismatch between digital pre-emphasis filter and PLL is calibrated. The loop filter $RC$ variation is tracked in the first place, and then the variation of the loop gain is calibrated by sensing the magnitude differences of the modulator between DC and ten times of the loop bandwidth. The proposed transmitter has been implemented in 0.18- $\mu{\rm m}$ CMOS technology for GSM/GPRS application. Measurement results show that the maximum RMS phase error of the proposed transmitter is 0.8 $^{\circ}$ . In addition, the measured calibration accuracies for $RC$ and loop gain variations are 0.5% and 0.8%, respectively. By reusing the PLL locking time, 18- $\mu{\rm s}$ calibration time is achieved. Moreover, most parts of the calibration circuitries can be shared with the receiver chain, reducing the circuit complexity overhead.

Frequency Response Bandwidth Calibration of High Speed Photodetector Using Frequency-Stabilized Laser by Optical Heterodyne Technique

In this paper, frequency-stabilized laser technology is introduced into photodetector frequency response measurement system. A 1531nm frequency-stabilized laser fulfilled by acetylene saturated absorption is employed to produce coherent light with a tunable laser source, gaining stable beat frequency light that reaches as high as several hundred ghz, fulfilling measurement of 40ghz high-speed photodetector frequency response bandwidth, and lowering impacts caused by instability of light frequency. In addition, measurement uncertainty analysis is conducted, which is better than 7 %(k=2).

A 58.9-dB ACR, 85.5-dB SBA, 5–26-MHz Configurable-Bandwidth, Charge-Domain Filter in 65-nm CMOS

A configurable-bandwidth charge-domain filter (CDF) with bandwidth calibration and clock-pulse modulation (CPM) is proposed. The bandwidth calibration scheme controls the insertion loss at a pre-specified frequency by modulating the feedback gain and delay; this helps the CDF to suppress the sinc distortion and thus achieve near-ideal brick-wall filtering. For multi-frequency compensation, a multi-stage CDF architecture is utilized to organize the feedback delay. Together with non-decimation filtering, the noise folding effect as well as the chip area can be reduced. On the other hand, to provide a stable gain under variable channel bandwidth, a CPM scheme is proposed; it adjusts the clock period with a fixed pulse width by zero-insertion. Implemented in a 65-nm CMOS technology, the proposed CDF achieves 58.9-dB adjacent-channel rejection (ACR), 85.5-dB stop-band attenuation (SBA), 41-dB conversion gain, and 19.5-MHz channel bandwidth at 320-MS/s input-sampling rate. Furthermore, for input-sampling rates range from 300 to 480 MS/s, the channel bandwidth can be configured from 5 to 26 MHz. At 1.2-V supply, the chip consumes 8.4-mW power and occupies 0.52-mm² area.

A 1.9–3.8 GHz $\Delta \Sigma$ Fractional-N PLL Frequency Synthesizer With Fast Auto-Calibration of Loop Bandwidth and VCO Frequency

A fast and high-precision all-digital automatic calibration circuit that is highly suited for ΔΣ fractional-N synthesizers is designed to achieve a constant loop bandwidth and fast lock time over an octave tuning range. A high-speed frequency-to-digital converter (FDC) measures VCO frequency on-chip with a sub-fREF frequency resolution of fREF/k in a time period of k·TREF. The on-chip detected VCO frequency is then used for calibrating the loop bandwidth and the VCO frequency. The loop bandwidth calibration circuit measures the VCO gain KVCO and uses it to precisely control the charge pump current, hence making the loop bandwidth constant. For the VCO frequency calibration, a minimum error code finding block significantly enhances the calibration accuracy by finding the truly closest code to the target frequency. Moreover, this method does not need to activate ΔΣ modulator to achieve sub- fREF calibration resolution, which makes this technique much accurate and faster than the conventional ones. A 1.9-3.8 GHz ΔΣ fractional-N synthesizer is implemented in 0.13 μm CMOS, demonstrating that the loop bandwidth calibration is completed in 1.1-6.0 μs with ±2% accuracy and the VCO frequency calibration is completed in 1.225-4.025 μs, all across the entire octave tuning range.

Full bandwidth calibration procedure for acoustic probes containing a pressure and particle velocity sensor

Calibration of acoustic particle velocity sensors is still difficult due to the lack of standardized sensors to compare with. Recently it is shown by Jacobsen and Jaud [J. Acoust. Soc. Am. 120, 830-837 (2006)] that it is possible to calibrate a sound pressure and particle velocity sensor in free field conditions at higher frequencies. This is done by using the known acoustic impedance at a certain distance of a spherical loudspeaker. When the sound pressure is measured with a calibrated reference microphone, the particle velocity can be calculated from the known impedance and the measured pressure. At lower frequencies, this approach gives unreliable results. The method is now extended to lower frequencies by measuring the acoustic pressure inside the spherical source. At lower frequencies, the sound pressure inside the sphere is proportional to the movement of the loudspeaker membrane. If the movement is known, the particle velocity in front of the loudspeaker can be derived. This low frequency approach is combined with the high frequency approach giving a full bandwidth calibration procedure which can be used in free field conditions using a single calibration setup. The calibration results are compared with results obtained with a standing wave tube.

Spectrophotometer spectral bandwidth calibration with absorption bands crystal standard

A procedure for calibration of a spectral bandwidth standard for high-resolution spectrophotometers is described. Symmetrical absorption bands for a crystal standard are adopted. The method relies on spectral band shape fitting followed by a convolution with the slit function of the spectrophotometer. A reference spectrophotometer is used to calibrate the spectral bandwidth standard. Bandwidth calibration curves for a minimum spectral transmission factor relative to the spectral bandwidth of the reference spectrophotometer are derived for the absorption bands at the wavelength of the band absorption maximum. The family of these calibration curves characterizes the spectral bandwidth standard. We calibrate the spectral bandwidth of a spectrophotometer with respect to the reference spectrophotometer by determining the spectral transmission factor minimum at every calibrated absorption band of the bandwidth standard for the nominal instrument values of the spectral bandwidth. With reference to the standard spectral bandwidth calibration curves, the relation of the spectral bandwidth to the reference spectrophotometer is determined. We determine the discrepancy in the spectrophotometers' spectral bandwidths by averaging the spectral bandwidth discrepancies relative to the standard calibrated values found at the absorption bands considered. A weighted average of the uncertainties is taken.

Scalability support for multiparty multimedia communications

In this paper, we propose a new communication abstraction known as the group channel which facilitates and supports the implementation of multiparty interactive multimedia (MIM) applications such as video conferencing. The group channel is a high-level abstraction for group communication. The credit scheme and the dynamic bandwidth calibration scheme are provided as an integral part of the group channel service for allocating network bandwidth dynamically as participants join and leave the group channel. The multimedia transport protocol (MTP) is proposed as a realization of the group channel service in the ATM network. Its prototype implementation and a simple multiparty video-conferencing application built on top of the MTP prototype are described in this paper. Our results show that the group channel is capable of guaranteeing the performance of MIM applications irrespective of the group size and differences in workstation speeds.