Curvature Compensation Method Research Articles

A Sub-1 ppm/°C Reference Voltage Source with a Wide Input Range

With the continuous advancement of electronic technology, the application of high-voltage integrated circuits is becoming increasingly prevalent in fields such as power systems, medical devices, and industrial automation. The reference circuit within high-voltage integrated circuits must not only exhibit insensitivity to temperature variations but also maintain stability across a broad voltage supply. This paper presents a bandgap reference (BGR) source capable of operating over a wide input range. This BGR employs a high-order curvature compensation method to eliminate nonlinear voltage terms, resulting in minimal temperature drift. The circuit achieves an impressive temperature coefficient (TC) of 0.88 ppm/°C over a temperature range from −40 °C to 130 °C. To ensure stable operation within a 4–40 V range, the design incorporates a pre-regulation circuit that stabilizes the supply voltage of the BGR core at a fixed value, thereby enhancing the ability to withstand variations in power supply voltage.

Fully Distributed Shape Sensing of a Flexible Surgical Needle Using Optical Frequency Domain Reflectometry for Prostate Interventions.

In minimally invasive procedures such as biopsies and prostate cancer brachytherapy, accurate needle placement remains challenging due to limitations in current tracking methods related to interference, reliability, resolution or image contrast. This often leads to frequent needle adjustments and reinsertions. To address these shortcomings, we introduce an optimized needle shape-sensing method using a fully distributed grating-based sensor. The proposed method uses simple trigonometric and geometric modeling of the fiber using optical frequency domain reflectometry (OFDR), without requiring prior knowledge of tissue properties or needle deflection shape and amplitude. Our optimization process includes a reproducible calibration process and a novel tip curvature compensation method. We validate our approach through experiments in artificial isotropic and inhomogeneous animal tissues, establishing ground truth using 3D stereo vision and cone beam computed tomography (CBCT) acquisitions, respectively. Our results yield an average RMSE ranging from 0.58 ± 0.21 mm to 0.66 ± 0.20 mm depending on the chosen spatial resolution, achieving the submillimeter accuracy required for interventional procedures.

Study on a curvature compensation method for improving the end face matching of large-segment steel box girders during full-span erection

As precast segments are increasingly preferred for bridge construction owing to their efficiency and environmentally benign attributes, this study aims to enhance the end face matching technology for large-segment steel box girders. The curvature compensation method, which is a form of extension of the elevation compensation for pre-camber setting, is proposed based on the unstressed geometry of the steel box girder. It is found that the curvature compensation is equivalent to the end face angle compensation of segments if the construction technology of “combining several straight lines into a curve” is adopted. Three practical formulas for calculating curvature compensation angles are derived, namely, the moment method, intersection angle secant method, and incremental moment method, and theoretical values of the errors caused by using matching line shape calculation are provided. Furthermore, considering the specific continuous bridge with large-segment steel box girders in the Shenzhen-Zhongshan Channel as a case study, the calculation results of manufacturing parameters, matching line shapes, and end matching are presented. The findings indicate that the curvature compensation angle's maximum error reaches 55.7 % when calculated conservatively using erection geometry, while the manufacturing geometry's maximum error reaches 4.84 cm if the curvature compensation angle is disregarded. The results of on-site monitoring show that the curvature compensation method proposed in this study is able to provide the continuous fabrication geometry and achieve the perfect matching of end faces of neighbouring large-segment steel box girders.

A 1.16-V 5.8-to-13.5-ppm/°C Curvature-Compensated CMOS Bandgap Reference Circuit With a Shared Offset-Cancellation Method for Internal Amplifiers

This article introduces an accurate current-mode bandgap reference circuit design with a novel shared offset compensation scheme for its internal amplifiers. This bandgap circuit has been designed to operate over a very wide temperature range from −40 °C to 150 °C. Its output voltage is 1.16 V with a 3.3-V supply voltage. A multi-section curvature compensation method alleviates the error from the bipolar junction transistor’s base–emitter nonlinear voltage dependence on temperature. The bandgap reference circuit contains two operational amplifiers that are utilized to generate proportional-to-absolute-temperature (PTAT) and complementary-to-absolute-temperature (CTAT) current sources. With the implementation of the described shared offset-cancellation methodology, the simulated output inaccuracy introduced by the amplifier is kept to a 5 $\sigma $ offset within ±4.6 $\mu \text{V}$ while allowing to conserve die size and power consumption by preventing that each amplifier is accompanied by its own active auxiliary offset-cancellation circuit. Designed and fabricated in a 130-nm CMOS process technology, the bandgap reference has a measured output voltage shift of less than 1 mV over a −40 °C to 150 °C temperature range and an overall variation of ±8.2 mV across seven measured samples without trimming.

A 2.5 ppm/°C Voltage Reference Combining Traditional BGR and ZTC MOSFET High-Order Curvature Compensation

This brief presents a voltage reference with high-order curvature compensation based on the zero temperature coefficient (ZTC) of MOSFET. The proposed voltage reference uses a conventional current reference to generate a constant current as of the bias of ZTCMOS. A curvature compensation method based on the α power model is combined with the conventional curvature compensation method to obtain a low temperature coefficient. Test results of the proposed voltage reference fabricated with the CSMC 0.18 μm CMOS process demonstrate that the output voltage is 628 mV. The trimmed temperature coefficient achieves 2.5 ppm/°C. The line sensitivity is 0.03 %/V, the chip area is 0.024 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , power consumption is 77 μW. The simulated power supply rejection ratio (PSRR) reaches -91.4 dB at 100 MHz.

Reflection loss field visualization of curved RAS based on scanning free-space measurement and curvature compensation using perfect electric conductor

Electromagnetic properties of radar absorbing structures (RASs) are highly affected by their curvatures. Therefore, novel full-field curvature compensation methods in the reflection loss evaluation of curved RASs are proposed. These methods are commonly based on the scanning free-space measurement (SFM), whose curvature compensation method is based on the measurement of the actual perfect electric conductor (PEC) or the PEC reflection loss function-based prediction, which allows the analysis of the original reflection loss of a curved RAS. In the first method, an actual PEC specimen with the same shape as the RAS to be evaluated is used, and the full-field reflection loss of the PEC is obtained by the SFM. As a measure, when the PEC specimen is not available, the second method using the PEC reflection loss function-based prediction is also proposed to obtain the full-field reflection loss of the PEC. This method can predict the reflection loss map of the PEC quickly by defining the PEC reflection loss function according to the curvature and incident angle using the data from measurement. To determine the PEC reflection loss function, it is necessary to secure the reflection loss maps of the PEC specimens with constant curvatures as database, which is also prepared easily by the SFM. Therefore, once they are measured, it can be applied to RASs with various curvatures based on simple compensation. The database for the PEC reflection loss maps with various constant curvatures is ready in the SFM system, and this curvature compensation method can be performed in real time during the scanning. The two methods are validated by comparing each other in double-curvature and airfoil-shaped RASs.

A high precision logarithmic-curvature compensated all CMOS voltage reference

This paper presents a resistor-less high-precision, sub-1 V all-CMOS voltage reference. A curvature-compensation method is used to cancel the logarithmic temperature dependence regardless of mobility temperature exponent $$(\upgamma)$$ . The circuit is simulated in 65 nm CMOS technology and yields an output voltage of 594 mV, temperature coefficient of $$7\frac{\text{ppm}}{{^{ \circ } {\text{C}}}}$$ in the range of −40 to 125 °C, a power supply rejection ratio (PSRR) of − 43 dB at of 100 Hz, a line sensitivity of $$\frac{{76\,\upmu{\text{V}}}}{\text{V}}$$ in the supply voltage range of 1.2 to 2 V, a power dissipation of $$1.4\,\upmu{\text{W}}$$ at 1.2 V supply and an output noise of $$2.8\frac{{\upmu{\text{V}}}}{{\sqrt {\text{Hz}} }}$$ at $$100\,{\text{Hz}}$$ . The total active area of the design is $$0.03\,{\text{mm}}^{2}$$ . This voltage reference is suitable for low-power, low-voltage applications which also require high precision.

Efficient Terahertz Wide-Angle NUFFT-Based Inverse Synthetic Aperture Imaging Considering Spherical Wavefront.

An efficient wide-angle inverse synthetic aperture imaging method considering the spherical wavefront effects and suitable for the terahertz band is presented. Firstly, the echo signal model under spherical wave assumption is established, and the detailed wavefront curvature compensation method accelerated by 1D fast Fourier transform (FFT) is discussed. Then, to speed up the reconstruction procedure, the fast Gaussian gridding (FGG)-based nonuniform FFT (NUFFT) is employed to focus the image. Finally, proof-of-principle experiments are carried out and the results are compared with the ones obtained by the convolution back-projection (CBP) algorithm. The results demonstrate the effectiveness and the efficiency of the presented method. This imaging method can be directly used in the field of nondestructive detection and can also be used to provide a solution for the calculation of the far-field RCSs (Radar Cross Section) of targets in the terahertz regime.

A Novel Wide-Temperature-Range, 3.9 ppm/$^{\circ}$C CMOS Bandgap Reference Circuit

This paper presents an innovative CMOS Bandgap Reference Generator topology that leads to an improved curvature compensation method over a very wide temperature range. The proposed design was implemented in a standard 0.35 μm CMOS process. The compensation is performed by using only poly-silicon resistors. This is achieved by using a second Op-amp that generates a CTAT current, which is subsequently used to enhance the curvature compensation method. The performance of the circuit was verified experimentally. Measured results have shown temperature coefficients as low as 3.9 ppm/°C over a temperature range of 165°C ( -15°C to 150°C ) and temperature coefficients as low as 13.7 ppm/°C over an extended temperature range of 200°C (-50°C to 150°C ). In addition the circuit demonstrated very good line regulation performance for a broad range of supply voltages. The measured line regulation at room temperature is 0.039% V.

Curvature-compensated BiCMOS bandgap with 1-V supply voltage

We present a bandgap circuit capable of generating a reference voltage of 0.53 V. The circuit, implemented In a submicron BiCMOS technology, operates with a supply voltage of 1 V, consuming 92 /spl mu/W at room temperature. In the bandgap circuit proposed, we use a nonconventional operational amplifier which achieves virtually zero systematic offset, operating directly from the 1-V power supply. The bandgap architecture used allows a straightforward implementation of the curvature compensation method. The proposed circuit achieves 7.5 ppm/K of temperature coefficient and 212 ppm/V of supply voltage dependence, without requiring additional operational amplifiers or complex circuits for the curvature compensation.