Analog Compensation Research Articles

A simple and effective method to compensate the thermal drift of implantable blood pressure sensors

This article presents a study of implantable blood pressure sensors based on a probe made up of four piezoresistors. An original method combining both measurements and calculations allows extracting the values of each piezoresistor without degrading the probe is developed. This study made it possible to create a simulation model in Cadence/Pspice electronic simulation software, considering the variation of the piezoresistor according to the temperature and the pressure. To our knowledge, no simulation model considering both the variation of the temperature and the pressure of each piezoresistor exists in the literature. So, the simulation of the sensor allows to quickly test the efficiency of the compensation circuit before its realization. Once the thermal drifts of the sensor have been quantified, a circuit based on PNP transistors is developed to compensate this thermal drift. This analog compensation technique ensures low cost, compactness and low power consumption. It proved experimentally effective in reducing thermal drift of the sensor. For example, the experimental thermal drift of the sensor is reduced from 9.97 mmHg/°C without compensation to 2.12 mmHg/°C after compensation at the pressure of 300 mmHg. This method has been validated with 3 pressure levels (0, 100, 200 and 300 mmHg).

A piezoelectric-driven nanoindentation system for scanning electron microscope with improved analog compensation method.

This paper presents a novel piezoelectric-driven nanoindentation system for a scanning electron microscope (SEM) with an improved analog compensation (IAC) method. This system mainly consists of a piezoelectric-driven indenter head, a rectangle-shaped transducer, and a nanopositioner module. Compared with the state-of-the-art piezoelectric-driven nanoindentation system with a circle-shaped transducer, the proposed nanoindentation system is capable of multi-direction operation inside a SEM with a rectangle-shaped transducer. Self-matched semiconductor strain gauges are selected as the position sensor for the piezoelectric-actuator. The Wheatstone bridge output voltage cannot achieve a zero temperature coefficient because the temperature coefficients of self-matched semiconductor strain gauge pairs become significantly different from each other after installation in practice. An IAC method is proposed to compensate the temperature coefficients further. Compared with the existing analog compensation method, the IAC method solves the problem of amplifier saturation and improves the sensitivity of the self-matched semiconductor strain gauge pairs position sensor by 27%. The multi-direction operation results inside a standard SEM HITACHI SU5000 validate the advantage of the developed nanoindentation system.

A 2MHz, low temperature coefficient relaxation oscillator with hybrid temperature compensation and real-time calibration

An RC relaxation oscillator (ROSC) with hybrid temperature compensation as well as the frequency of 2 MHz is proposed in this paper. Frequency stability is enhanced with analog compensation by replicating the path of comparator and level determination logic (LDL), the compensation approach removes the temperature-dependent delay of the comparator and LDL. Since frequency is undesirable at low temperatures (below 0 °C) due to non-zero-temperature-coefficient current and voltage references, as well as weak carrier mobility, digital low temperature compensation is presented to extend the oscillator’s operating temperature range to −40 °C–125 °C. The digital compensation module, after hybrid compensation, is then utilized for real-time oscillator calibration by the same operating principle. The presented oscillator with hybrid compensation and real-time calibration is developed in a standard 0.18-μm CMOS process with the active area of 0.04 mm2, and post-simulation results reveal that after hybrid compensation, the temperature coefficient (TC) of this oscillator is 43.97 ppm/°C in the temperature range of −40 °C–125 °C. The power of this ROSC is 185 μW when the supply voltage is 1.8V.

Mitigation of Leakage and Stationary Clutters in Short-Range FMCW Radar With Hybrid Analog and Digital Compensation Technique

In short-range sensing, the frequency-modulated continuous-wave (FMCW) radar is subject to the leakage between the transmitter (Tx) and the receiver (Rx) and the stationary clutter reflections, which are difficult to deal with due to the proximity to the target. The proximity ghost image may not only interfere with the target but also pose limitations on the radar performance, such as the degradation of the signal-to-noise ratio (SNR). This article proposes a novel hybrid analog and digital compensation techniques, which mitigates the leakage and the stationary clutters by compensating with the prestored anti-interference signals in both analog and digital domains at the intermediate-frequency (IF) stage. A novel modulation signal-based synchronization (MBS) technique is developed to align the real-time IF signal with the anti-interference signal during the compensation process. By significantly suppressing both the Tx-Rx leakage and the stationary clutters, the proposed technique greatly improves the signal-to-interference ratio (SIR) of the IF beat signals and makes possible the detection of targets with weak reflections. Moreover, the analog compensation enables the full use of the dynamic range of the analog-to-digital converter (ADC), which will reduce the impact of quantization noise and, thus, improve the SNR. Experiments have been carried out to validate the performance of the proposed technique in leakage compensation, weak target detection, stationary clutter compensation, and gesture sensing. The experimental results show that the SIR and the SNR have been improved by around 38 and 10 dB, respectively.

A Multiple-Time-Scale Analog Circuit for the Compensation of Long-Term Memory Effects in GaN HEMT-Based Power Amplifiers

In this article, we present an analog circuit for the compensation of long-term memory effects in power amplifiers (PAs) based on GaN high-electron-mobility transistors (HEMTs). The analog compensation circuit (ACC) is supported on a charge-trapping behavioral model that features a state-dependent variable emission time constant, rather than a fixed emission time constant. This allows not only for the more accurate modeling and compensation of the nonlinear long-term memory effects experienced by GaN HEMT-based PAs, but also for the adaptation of the dynamics of the ACC to varying operating conditions, such as the ambient temperature. We demonstrate that the proposed ACC is able to successfully eliminate any multiple-time-constant transient symptom of current collapse following a high-power radio-frequency pulse or two-tone excitation and accurately preserve the class of operation of a GaN HEMT-based PA. Moreover, we also demonstrate that the proposed ACC can aid the linearization of GaN HEMT-based PAs for fifth-generation (5G) New Radio (NR) communications, allowing for the reduction in the complexity of the digital predistorter. For a 5G NR time-division duplexing signal with a bandwidth of 20 MHz, the inclusion of the ACC improved out-of-band emissions by over 15 dB and improved the error-vector magnitude by over 10 p.p. at essentially no cost to the PA’s power-added efficiency.

Analog I/Q FIR Filter in 55-nm SiGe BiCMOS for 16-QAM Optical Communications at 112 Gb/s

We propose a novel implementation of a complex analog equalization filter for the compensation of frequency-dependent variations in coherent optical links. The analog compensation filter can be used in coherent-lite optical communication links where digital signal processing (DSP) is removed to limit the complexity and power consumption. In these links, the filter can compensate for electrical bandwidth limitations and distortion introduced by chromatic dispersion in the fiber. The complex filter is implemented by combining four distributed analog finite-impulse response (FIR) filters to obtain the necessary response. The filter delays are implemented using active delay cell structures to create a compact solution. The analog filter is implemented in a 55-nm BiCMOS technology and consumes 185-mW core power for five complex filter taps. Performance is evaluated using the S-parameter measurements, noise and linearity measurements, and real-time system experiments using 112-Gb/s 16-QAM-modulated signals.

A 9.2-g Fully-Flexible Wireless Ambulatory EEG Monitoring and Diagnostics Headband With Analog Motion Artifact Detection and Compensation.

An 8-channel wearable wireless device for ambulatory surface EEG monitoring and analysis is presented. The entire multi-channel recording, quantization, and motion artifact removal circuitries are implemented on a 4-layer polyimide flexible substrate. The recording electrodes and active shielding are also integrated on the same substrate, yielding the smallest form factor compared to the state of the art. Thanks to the dry non-contact electrodes, the system is quickly mountable with minimal assistance required, making it an ideal ambulatory front- and temporal-lobe EEG monitoring device. The flexible main board is connected to a rechargeable battery on one end and to a 13×17mm 2 rigid board on the other end. The mini rigid board hosts a low-power programmable FPGA and a BLE 5.0 transceiver, which add diagnostic capability and wireless connectivity features to the device, respectively. Design considerations for a wearable EEG monitoring and diagnostic device are discussed in details. The theory of the novel fully-analog method for motion artifact detection and removal is described and the detailed circuit implementation is presented. The device performance in terms of voltage gain (260 V/V), bandwidth (DC-300 Hz), motion artifact removal, and wireless communication throughput (up to 1Mbps) is experimentally validated. The entire wearable solution with the battery weighs 9.2 grams.

ОПТИМІЗАЦІЯ ВИМІРЮВАЛЬНИХ ЗАСОБІВ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ ЗА ДОПОМОГОЮ ТЕНЗОДАТЧИКІВ

In the article, the principles of construction, design and mathematical modeling of deformation and stresses of complex technical constructions are developed with the help of strain gauges and strain gauges taking into account destabilizing factors, which allows to significantly reduce the level of errors in relation to existing measurement methods and known analogs.The method of digital compensation provides a more significant reduction in the errors of measuring transducers compared with the method of analog compensation. Features and technical indicators of this method are considered on an example of measuring pressure transducer with foil strain gauges.This method is universal, allows us to adjust not only the errors of the measurement channel nonlinearity and additional errors but also the errors associated with the effect of interferences of the general type due to ground resistance, which induces the connection between the measuring channels of the main and destabilizing factor.The disadvantages of this method include a significant amount of computations, which sharply increases with increasing order of approximating polynomials.The purpose is to develop a method and means of measuring stress-strain state using strain gauge, free from the above - mentioned shortcomings.The main destabilizing factors that limit the measurement accuracy using strain gauge are:- random processes (noises, obstacles, etc.);- changes in parameters of measuring transducers due to aging and physical degradation;- effects of external climatic and mechanical factors (temperature, humidity, etc.).The influence of the main destabilizing factors limiting the accuracy of the measurement of the stress-strain state of complex technical constructions with the help of strain gauges was analyzed, among which the influences of external climatic and mechanical factors are one of the most important ones. Regarding the systematic components, the most important in statistical measurements are the errors of nonlinearity and the temperature component of the error.For the study, two main alloys were taken, which today has the widest use as a material for strain gauges - it is constantan and karma. For these materials, the influence of the range of temperature changes, the spread of the values of temperature error on the mean-square value of the error of approximation by power polynomials was investigated.Using the NUMERY package, the dependence of the approximation error on the order of the approximating polyphony was determined. It is established that the mean square error value in the wide temperature range for both constantan and karma has a weak correlation with the order of a polynomial.

РОЗРОБКА СПОСОБУ ТА ЗАСОБУ ВИМІРЮВАНЬ НАПРУЖЕНО – ДЕФОРМОВАНОГО СТАНУ ЗА ДОПОМОГОЮ ТЕНЗОДАТЧИКА

Nowadays due to the modern wave of intellectualization of measuring instruments the digital methods of correction not only for primary measuring transducers, but also for secondary sensors are practiced on a large scale. Since the conversion function of secondary measuring transducers is linear, the method of model measures by two points is used for automatic correction of systematic components of the errors of such converters. The method of digital compensation, which provides a more significant reduction in the errors of measuring transducers compared with the method of analog compensation has been described. Features and technical indicators of this method are considered on the example of measuring pressure transducer with foil strain gauges. This method is universal, allows to adjust not only the errors of measurement channel nonlinearity and additional errors, but also the errors associated with the effect of interferences of general type due to ground resistance, which induces the connection between measuring channels of the main and destabilizing factor. The disadvantages of this method include a significant amount of computations, which sharply increases with the increase of the order of approximating polynomials. The aim of the paper is to develop a method and means of measuring stress-strain state using strain gauge, free from the above mentioned shortcomings. The main destabilizing factors that limit the measurement accuracy using strain gauge are the following: - random processes (noises, obstacles, etc.); - changes in parameters of measuring transducers due to aging and physical degradation; - effects of external climatic and mechanical factors (temperature, humidity, etc.). Regarding systematic components, the errors of nonlinearity and temperature component of the error are the most important in statistical measurements. We have studied the influence of temperature range variations, the spread of values of temperature error (± 10 %) on the mean square error of approximation by power polynomials. Using the NUMERY Program, the dependence of approximation error on the order of approximating polynomial has been determined. It is established that in a wide temperature range, the error for constantan has a weak relation with the order of a polynomial.

Optimization of work of the instrument system of measurement of the stress - deformed state of complex technical objects and systems

Nowadays the modern wave of intellectualization of measuring instruments proposes the digital methods of correction are acquired not only for primary measuring transducers, but also for secondary sensors. Since the conversion function of the secondary measuring transducers is linear, the method of the model measures by two points is used for automatic correction of the systematic components of the errors of such converters.The method of digital compensation was describe [4], which provides a more significant reduction in the errors of measuring transducers compared with the method of analog compensation. Features and technical indicators of this method are considered on an example of measuring pressure transducer with foil strain gauges.This method is universal, allows us to adjust not only the errors of the measurement channel nonlinearity and additional errors, but also the errors associated with the effect of interferences of the general type due to ground resistance, which induces the connection between the measuring channels of the main and destabilizing factor.The disadvantages of this method include a significant amount of computations, which sharply increases with increasing order of approximating polynomials.The purpose is to develop a method and means of measuring stress - strain state using strain gauge, free from the above - mentioned shortcomings.The main destabilizing factors that limit the measurement accuracy using strain gauge are:- Random processes (noises, obstacles, etc.);- Changes in parameters of measuring transducers due to aging and physical degradation;- Effects of external climatic and mechanical factors (temperature, humidity, etc.).Regarding the systematic components, the most important in statistical measurements are the errors of nonlinearity and the temperature component of the error.We studied the influence of temperature range variations, the spread of values of temperature error (± 10%) on the mean square error of approximation by power polynomials.Using the NUMERY Program, the dependence of the approximation error on the order of the approximating polyphony was determined.It is established that in a wide temperature range, the error for constantan has a weak relation with the order of a polynomial.

A ±4-A High-Side Current Sensor With 0.9% Gain Error From −40 °C to 85 °C Using an Analog Temperature Compensation Technique

This paper presents a fully integrated shunt-based current sensor that supports a 25-V input common-mode range while operating from a single 1.5-V supply. It uses a high-voltage beyond-the-rails ADC to directly digitize the voltage across an on-chip shunt resistor. To compensate for the shunt’s large temperature coefficient of resistance (~0.335%/°C), the ADC employs a proportional-to-absolute-temperature voltage reference. This analog compensation scheme obviates the need for the explicit temperature sensor and calibration logic required by digital compensation schemes. The sensor achieves 1.5-V noise over a 2-ms conversion time while drawing only 10.9 $\mu \text{A}$ from a 1.5-V supply. Over a ±4-A range, and after a one-point trim, the sensor exhibits a 0.9% (maximum) gain error from −40 °C to 85 °C and a 0.05% gain error at room temperature.

Line-impedance matching and signal conditioning capabilities for high-speed feed-forward voltage-mode transmit drivers

This work presents the design and implementation of a power-efficient 2-tap feed-forward voltage mode driver which has impedance tuning and signal conditioning capabilities. The driver has a robust mechanism to match its impedance to the line impedance even when signal conditioning is enabled which minimizes reflection and improves signal quality. A mixed signal approach that detects and compensates for NMOS and PMOS transistor resistance variation is presented. An analog circuit detects the driver's resistance variation, and a digital circuit controls an analog compensation circuit to maintain line impedance matching for all signal conditioning configurations of the driver. When maximum signal conditioning is enabled, the driver can transmit a 40Gbits/sec PRBS7 signal through a 10 in. FR4 channel. It achieves a differential eye-opening amplitude of 100mVppd and an eye-opening width of 0.8UI consuming 9.7mW of at-speed power. Simulations demonstrate that worst case impedance deviation from 50Ω due to process, voltage and temperature variation is 2.7%. The driver is designed in 28nm CMOS process using a 0.85V nominal supply voltage. It is simulated using HSPICE circuit simulator and mixed mode simulations tools.

Research of Phase Compensation Technology in Electronic Instrument Transformer

Introduces the analog phase compensation technology used in electronic instrument transformer, put forward a method of digital phase compensation in electronic transformer and carries out in the 220KV electronic instrument transformer measurement system, the resolution ratio of the phase compensation is 1 second and the maximum range of the phase compensation is 270 second, which can meet the phase adjustment of electronic instrument transformer; compares the analog compensation technology and digital phase compensation technology, analyzes their characteristics and different applications.

A 0.5-V 35-$ \mu $W 85-dB DR Double-Sampled $\Delta\Sigma$ Modulator for Audio Applications

This paper presents a 0.5-V 1.5-bit double-sampled ΔΣ modulator for audio applications. Unlike existing double-sampled designs, the proposed double-sampled ΔΣ modulator employs an input-feedforward topology to reduce internal signal swings, thereby relaxing design requirements for the low-voltage building blocks and reducing distortion. Moreover, in order to avoid instability and noise shaping degradation, the proposed architecture restores the noise transfer function (NTF) of the double-sampled modulator to its single-sampled equivalent with the help of compensation loops. In the circuit implementation, the proposed fully-differential amplifier adopts an inverter output stage and a common-mode feedback (CMFB) circuit with a global feedback loop in order to reduce power consumption. A resistor-string-reference switch matrix based on a direct summation quantizer is used to simplify the analog compensation loop. The chip prototype has been fabricated in a 0.13-μm CMOS technology with a core area of 0.57 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The measured results show that when operating from a 0.5-V supply and clocked at 1.25 MHz, the modulator achieves a peak signal-to-noise and distortion ratio (SNDR) of 81.7 dB, a peak signal-to-noise ratio (SNR) of 82.4 dB and a dynamic range (DR) of 85.0 dB while consuming 35.2 μW for a 20-kHz signal bandwidth.

The Third Transmembrane Segment of Orai1 Protein Modulates Ca2+ Release-activated Ca2+ (CRAC) Channel Gating and Permeation Properties

Orai1, the pore subunit of Ca(2+) release-activated Ca(2+) channels, has four transmembrane segments (TMs). The first segment, TMI, lines the pore and plays an important role in channel activation and ion permeation. TMIII, on the other hand, does not line the pore but still regulates channel gating and permeation properties. To understand the role of TMIII, we have mutated and characterized several residues in this domain. Mutation of Trp-176 to Cys (W176C) and Gly-183 to Ala (G183A) had dramatic effects. Unlike wild-type channels, which exhibit little outward current and are activated by STIM1, W176C mutant channels exhibited a large outward current at positive potentials and were constitutively active in the absence of STIM1. G183A mutant channels also exhibited substantial outward currents but were active only in the presence of 2-aminoethoxydiphenyl borate (2-APB), irrespective of STIM1. With W176C mutant channels inward, monovalent currents were blocked by Ca(2+) with a high affinity similar to the wild type, but the Ca(2+)-dependent blocking of outward currents differed in the two cases. Although a 50% block of the WT outward current required 250 μm Ca(2+), more than 6 mm was necessary to have the same effect on W176C mutant channels. In the presence of extracellular Ca(2+), W176C and G183A outward currents developed slowly in a voltage-dependent manner, whereas they developed almost instantaneously in the absence of Ca(2+). These changes in permeation and gating properties mimic the changes induced by mutations of Glu-190 in TMIII and Asp-110/Asp-112 in the TMI/TMII loop. On the basis of these data, we propose that TMIII maintains negatively charged residues at or near the selectivity filter in a conformation that facilitates Ca(2+) inward currents and prevents outward currents of monovalent cations. In addition, to controlling selectivity, TMIII may also stabilize channel gating in a closed state in the absence of STIM1 in a Trp-176-dependent manner.

A Review of PVT Compensation Circuits for Advanced CMOS Technologies

The recent high-performance interfaces like DDR2, DDR3, USB and Serial ATA require their output drivers to provide a minimum variation of rise and fall times over Process, Voltage, and Temperature (PVT) and output load variations. As the interface speed grows up, the output drivers have been important component for high quality signal integrity, because the output voltage levels and slew rate are mainly determined by the output drivers. The output driver impedance compliance with the transmission line is a key factor in noise minimization due to the signal reflections. In this paper, the different implementations of PVT compensation circuits are analyzed for cmos45nm and cmos65nm technology processes. One of the considered PVT compensation circuits uses the analog compensation approach. This circuit was designed in cmos45nm technology. Other two PVT compensation circuits use the digital compensation method. These circuits were designed in cmos65nm technology. Their electrical characteristics are matched with the requirements for I/O drivers with respect to DDR2 and DDR3 standards. DDR2 I/O design was done by the Freescale wireless design team for mobile phones and later was re-used for other high speed interface designs. In conclusion, the advantages and disadvantages of considered PVT control circuits are analyzed.

Analog compensation of parasitic sensor signals in a subsampling impedance analyzer circuit for resonating sensors

Many sensor signals are afflicted with unwanted components induced by parasitic but well known sensor effects. With utilization of digitizing interface circuits the suppression of these components is typically performed in the digital domain. Hence the effective resolution of the system is reduced, especially when unwanted signal components are dominating the signal’s magnitude. In this contribution, a method of parasitic signal compensation as implemented in an impedance analyzer circuit for a quartz crystal resonating sensor is presented.

Identification of an Evolutionarily Conserved Extracellular Threonine Residue Critical for Surface Expression and Its Potential Coupling of Adjacent Voltage-sensing and Gating Domains in Voltage-gated Potassium Channels

The dynamic expression of voltage-gated potassium channels (Kvs) at the cell surface is a fundamental factor controlling membrane excitability. In exploring possible mechanisms controlling Kv surface expression, we identified a region in the extracellular linker between the first and second of the six (S1-S6) transmembrane-spanning domains of the Kv1.4 channel, which we hypothesized to be critical for its biogenesis. Using immunofluorescence microscopy, flow cytometry, patch clamp electrophysiology, and mutagenesis, we identified a single threonine residue at position 330 within the Kv1.4 S1-S2 linker that is absolutely required for cell surface expression. Mutation of Thr-330 to an alanine, aspartate, or lysine prevented surface expression. However, surface expression occurred upon co-expression of mutant and wild type Kv1.4 subunits or mutation of Thr-330 to a serine. Mutation of the corresponding residue (Thr-211) in Kv3.1 to alanine also caused intracellular retention, suggesting that the conserved threonine plays a generalized role in surface expression. In support of this idea, sequence comparisons showed conservation of the critical threonine in all Kv families and in organisms across the evolutionary spectrum. Based upon the Kv1.2 crystal structure, further mutagenesis, and the partial restoration of surface expression in an electrostatic T330K bridging mutant, we suggest that Thr-330 hydrogen bonds to equally conserved outer pore residues, which may include a glutamate at position 502 that is also critical for surface expression. We propose that Thr-330 serves to interlock the voltage-sensing and gating domains of adjacent monomers, thereby yielding a structure competent for the surface expression of functional tetramers.

P‐8: A New Hybrid Analog‐Digital Driving Method to Improve AMOLED Lifetime

AbstractWe propose a new hybrid pixel driving method that combines conventional digital driving with analog compensation for the declining electrical performance that occurs as OLEDs age. Image uniformity, and thus display lifetime, is improved by directly measuring the variation in OLED voltage at each pixel for a given OLED current level and then controlling the voltage drop across its driving TFT of an individual pixel.

CO/sub 2/ laser pulse monitoring instrument based on PVDF pyroelectric array

This paper proposes to extend the use of low-cost, pyroelectric, polyvinylidene fluoride four-quadrant arrays, originally devoted to monitoring the beam point stability of CO/sub 2/ laser beams, to the temporal profiling of the same laser pulse providing an instrument that is not commercially available. The advantage of using a single sensor for both types of measurements can be fully exploited if the pyroelectric sensor bandwidth is made almost flat in the typical frequency range (10 Hz-20 kHz) of the signal spectrum generated by a modulated CO/sub 2/ laser. In this paper, we present the design of an active analog compensation filter aimed to improve the reconstruction accuracy of the laser pulses and its circuit implementation with a quad operational amplifier for an easy integration of the compensation filter on the same board hosting the sensor. Experimental results obtained with modulated CO/sub 2/ laser beams, at pulse repetition rates from 10 to 1000 Hz and variable duty cycle, proved accurate in the laser pulse reconstruction with sensitivity of commercial semiconductor HgCdZnTe sensors.