This paper proposes an improved exponential curvature-compensated bandgap reference circuit to exploit the exponential relationship between the current gainβof the bipolar junction transistor(BJT)and the temperature ...This paper proposes an improved exponential curvature-compensated bandgap reference circuit to exploit the exponential relationship between the current gainβof the bipolar junction transistor(BJT)and the temperature as well as reduce the influence of resistance-temperature dependency.Considering the degraded circuit performance caused by the process deviation,the trimmable module of the temperature coefficient(TC)is introduced to improve the circuit stability.The circuit has the advantages of simple structure,high linear stability,high TC accuracy,and trimmable TC.It consumes an area of 0.09 mm^(2)when fabricated by using the 0.25-μm complementary metal-oxide-semiconductor(CMOS)process.The proposed circuit achieves the simulated power supply rejection(PSR)of about-78.7 dB@1 kHz,the measured TC of~4.7 ppm/℃over a wide temperature range from-55℃to 125℃with the 2.5-V single-supply voltage,and the tested line regulation of 0.10 mV/V.Such a high-performance bandgap reference circuit can be widely applied in high-precision and high-reliability electronic systems.展开更多
A low voltage bandgap reference with curvature compensation is presented. Using current mode structure, the proposed bandgap circuit has a minimum voltage of 900mV. Compensated through the VEB linearization technique,...A low voltage bandgap reference with curvature compensation is presented. Using current mode structure, the proposed bandgap circuit has a minimum voltage of 900mV. Compensated through the VEB linearization technique, this bandgap reference can reach a temperature coefficient of 10ppmFC from 0 to 150℃. With a 1.1V supply voltage,the supply current is 43μA and the PSRR is 55dB at DC frequency. This bandgap reference has been verified in a UMC 0.18μm mixed mode CMOS technology and occupies 0. 186mm^2 of chip area.展开更多
A new method,namely multiple point curvature compensation （MPCC）,is proposed for the design of a bandgap reference,and its design principles, theoretical derivation, and one feasible circuitry implementation are pre...A new method,namely multiple point curvature compensation （MPCC）,is proposed for the design of a bandgap reference,and its design principles, theoretical derivation, and one feasible circuitry implementation are presented. Being different from traditional techniques, this idea focuses on finding multiple temperatures in the whole range at which the first order derivatives of the output reference voltage equal zero. In this way, the curve of the output reference voltage is flattened and a better effect of curvature compensation is achieved. The circuitry is simulated in ST Microelectronics 0. 18μm CMOS technology, and the simulated result shows that the average temperature coefficient is only 1ppm/℃ in the range from - 40 to 125℃.展开更多
Parts with varied curvature features play increasingly critical roles in engineering, and are often machined under high-speed continuous-path running mode to ensure the machining efficiency. However, the continuous-pa...Parts with varied curvature features play increasingly critical roles in engineering, and are often machined under high-speed continuous-path running mode to ensure the machining efficiency. However, the continuous-path running trajectory error is significant during high-feed-speed machining, which seriously restricts the machining precision for such parts with varied curvature features. In order to reduce the continuous-path running trajectory error without sacrificing the machining efficiency, a pre-compensation method for the trajectory error is proposed. Based on the formation mechanism of the continuous-path running trajectory error analyzed, this error is estimated in advance by approximating the desired toolpath with spline curves. Then, an iterative error pre-compensation method is presented. By machining with the regenerated toolpath after pre-compensation instead of the uncompensated toolpath, the continuous-path running trajectory error can be effectively decreased without the reduction of the feed speed. To demonstrate the feasibility of the proposed pre-compensation method, a heart curve toolpath that possesses varied curvature features is employed. Experimental results indicate that compared with the uncompensated processing trajectory, the maximum and average machining errors for the pre-compensated processing trajectory are reduced by 67.19% and 82.30%, respectively. An easy to implement solution for high efficiency and high precision machining of the parts with varied curvature features is provided.展开更多
A lowtemperature coefficient（ TC） bandgap reference（ BGR） with novel process variation calibration technique is proposed in this paper. This proposed calibration technique compensating both TC and output value of ...A lowtemperature coefficient（ TC） bandgap reference（ BGR） with novel process variation calibration technique is proposed in this paper. This proposed calibration technique compensating both TC and output value of BGR achieves fine adjustment step towards the reference voltage,while keeping optimal TC by utilizing large resistance to help layout match. The high-order curvature compensation realized by poly and p-diffusion resistors is introduced into the design to guarantee the temperature characteristic. Implemented in 180 nm technology,the proposed BGR has been simulated to have a power supply rejection ratio（ PSRR） of 91 dB@100 Hz. The calibration technique covers output voltage scope of 0. 49 V-0. 56 Vwith TC of 9. 45 × 10^（-6）/℃-9. 56 × 10^（-6）/℃ over the temperature range of-40 ℃-120 ℃. The designed BGR provides a reference voltage of 500 mV,with measured TC of 10. 1 × 10^（-6）/℃.展开更多
A novel curvature-compensated CMOS bandgap voltage reference is presented. The reference utilizes two first order temperature compensations generated from the nonlinearity of the finite current gain β of vertical pnp...A novel curvature-compensated CMOS bandgap voltage reference is presented. The reference utilizes two first order temperature compensations generated from the nonlinearity of the finite current gain β of vertical pnp bipolar transistor. The proposed circuit, designed in a standard 0.18 μm CMOS process, achieves a good temperature coefficient of 2.44 ppm/℃ with temperature range from --40℃ to 85 ℃, and about 4 mV supply voltage variation in the range from 1.4 V to 2.4 V. With a 1.8 V supply voltage, the power supply rejection ratio is -56dB at 10MHz.展开更多
BACKGROUND Myopia and high myopia are global public health concerns.Patients with high myopia account for 0.5%-5.0%of the global population.AIM To examine diopters,axial length(AL),higher-order aberrations,and other o...BACKGROUND Myopia and high myopia are global public health concerns.Patients with high myopia account for 0.5%-5.0%of the global population.AIM To examine diopters,axial length(AL),higher-order aberrations,and other ocular parameters in Chinese children with myopia,to analyze the influence of structural parameters associated with myopia on visual quality,and to provide a theoretical basis for the prevention and treatment of childhood myopia and high myopia.METHODS This study included 195 children aged 6–17 years with myopia.The AL was measured with an ultrasonic ophthalmic diagnostic instrument,and the aberrations,corneal curvature(minimum K1,maximum K2,and average Km),central corneal thickness,anterior chamber depth,and anterior chamber angle were measured using a Sirius three-dimensional anterior segment analyzer.Using a standard formula,the corneal radius of curvature R(337.3/Km)and AL/R values were obtained.RESULTS The diopter of high myopia compared with low-middle myopia was correlated with age and AL(r=-0.336,-0.405,P<0.001),and AL of high myopia was negatively correlated with K1,K2,and Km(r=-0.673,-0.661,and-0.680,respectively;P<0.001),and positively correlated with age and the anterior chamber depth(r=0.214 and 0.275,respectively;P<0.05).AL/R was more closely related to diopter than AL in children with myopia,and 94.4%of children with myopia had an AL/R of>3.00.CONCLUSION The ocular structural parameters of children change because of different diopters.AL/R is more specific and sensitive than AL in evaluating the refractive status of myopia in children.An AL/R of>3.00 may be used as a specific index of myopia in children.There are differences in AL/R between high myopia and low-middle myopia,which can be used for the classification of ametropia.The degree of myopia has a certain influence on higher-order aberrations.展开更多
The precision controlling technology is a key step for the modern ship construction, with the precision controlling of the ship-hull curvature as one of bottlenecks in shipbuilding, where the initial is to present a c...The precision controlling technology is a key step for the modern ship construction, with the precision controlling of the ship-hull curvature as one of bottlenecks in shipbuilding, where the initial is to present a compensation value for the ship-hull plate precisely. The compensation value of the curvature plate is composed of two parts: the construction compensation, which results in the process of heating construction of curvature plate, and the assembling compensation, which results in welding ribbed stiffeners onto the curvature plate. Based on the developed computation system for the local contraction value, this paper presents a method to establish the experimented samples for the assembling compensation by means of numerical experiments, and another method to establish the practical mathematical model for the construction compensation of curvature plate. Furthermore, it introduces the experimental measuring method for the assembling compensation of the curvature plate, based on which the related database system has been developed. Numerical examples are analyzed to demonstrate the process to establish mathematical model for the assembling compensation values.展开更多
A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some su...A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some sub ranges.At different temperature sub ranges the bandgap reference can be compensated by different linear functions.Since the temperature sub range is much narrower than the whole range,the compensation error can be reduced significantly.Theoretically,the precision can be improved unlimitedly if the sub ranges are narrow enough.In the given example,with only three temperature sub ranges,the temperature coefficient of a conventional bandgap reference drops from 1 5×10 -5 /℃ to 2×10 -6 /℃ over the -40℃ to 120℃ temperature range.展开更多
A high precision high-order curvature-compensated bandgap reference compatible with the standard Bi-CMOS process,which uses a simple structure to realize a novel exponential curvature compensation in lower temperature...A high precision high-order curvature-compensated bandgap reference compatible with the standard Bi-CMOS process,which uses a simple structure to realize a novel exponential curvature compensation in lower temperature ranges,and a piecewise curvature correction in higher temperature ranges,is presented.Experiment results of the proposed bandgap reference implemented with a 0.6-μm BCD process demonstrate that a temperature coefficient of 2.9 ppm/℃is realized at a 3.6-V power supply,a power supply rejection ratio of 85 dB is achieved,and the line regulation is better than 0.318 mV/V for 2.2-5 V supply voltage dissipating a maximum supply current of 45μA.The active area of the presented bandgap reference is 260×240μm;.展开更多
A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate volt...A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate voltage｜VGS｜p of a PMOS transistor working in the saturated region. The second sub-reference is the weighted sum of gate-source voltages｜VGS｜n of NMOS transistors in the subthreshold region and the difference between two base-emitter voltages △VBE of bipolar junction transistors （BJTs）. The voltage reference implemented utilizing the proposed curvature compensation technique exhibits a low temperature coefficient and occupies a small silicon area. The proposed technique was verified in 0.18 μm standard CMOS process technology. The performance of the circuit has been measured. The measured results show a temperature coefficient as low as 12.7 pprrd /℃ without trimming, over a temperature range from -40 to 120℃, and the current consumption is 50 μA at room temperature. The measured power-supply rejection ratio （PSRR） is -31.2 dB @ 100 kHz. The circuit occupies an area of 0.045 mm2.展开更多
A novel high-order curvature compensation negative voltage bandgap reference （NBGR） based on a novel multilevel compensation technique is introduced. Employing an exponential curvature compensation （ECC） term with...A novel high-order curvature compensation negative voltage bandgap reference （NBGR） based on a novel multilevel compensation technique is introduced. Employing an exponential curvature compensation （ECC） term with many high order terms in itself, in a lower temperature range （TR） and a multilevel curvature compen- sation （MLCC） term in a higher TR, a flattened and better effect of curvature compensation over the TR of 165℃ （--40 to 125 ℃） is realised. The MLCC circuit adds two convex curves by using two sub-threshold operated NMOS. The proposed NBGR implemented in the Central Semiconductor Manufacturing Corporation （CSMC） 0.5 #m BCD technology demonstrates an accurate voltage of-1.183 V with a temperature coefficient （TC） as low as 2.45 ppm/℃over the TR of 165℃ at a -5.0 V power supply; the line regulation is 3 mV/V from a -5 to -2 V supply voltage. The active area of the presented NBGR is 370×180 μm2.展开更多
A new low-voltage CMOS bandgap reference （BGR） that achieves high temperature stability is proposed. It feeds back the output voltage to the curvature compensation circuit that constitutes a closed loop circuit to c...A new low-voltage CMOS bandgap reference （BGR） that achieves high temperature stability is proposed. It feeds back the output voltage to the curvature compensation circuit that constitutes a closed loop circuit to cancel the logarithmic term of voltage VBE. Meanwhile a low voltage amplifier with the 0.5 μm low threshold technology is designed for the BGR. A high temperature stability BGR circuit is fabricated in the CSMC 0.5μm CMOS technology. The measured result shows that the BGR can operate down to 1 V, while the temperature coefficient and line regulation are only 9 ppm/℃ and 1.2 mV/V, respectively.展开更多
文摘This paper proposes an improved exponential curvature-compensated bandgap reference circuit to exploit the exponential relationship between the current gainβof the bipolar junction transistor(BJT)and the temperature as well as reduce the influence of resistance-temperature dependency.Considering the degraded circuit performance caused by the process deviation,the trimmable module of the temperature coefficient(TC)is introduced to improve the circuit stability.The circuit has the advantages of simple structure,high linear stability,high TC accuracy,and trimmable TC.It consumes an area of 0.09 mm^(2)when fabricated by using the 0.25-μm complementary metal-oxide-semiconductor(CMOS)process.The proposed circuit achieves the simulated power supply rejection(PSR)of about-78.7 dB@1 kHz,the measured TC of~4.7 ppm/℃over a wide temperature range from-55℃to 125℃with the 2.5-V single-supply voltage,and the tested line regulation of 0.10 mV/V.Such a high-performance bandgap reference circuit can be widely applied in high-precision and high-reliability electronic systems.
文摘A low voltage bandgap reference with curvature compensation is presented. Using current mode structure, the proposed bandgap circuit has a minimum voltage of 900mV. Compensated through the VEB linearization technique, this bandgap reference can reach a temperature coefficient of 10ppmFC from 0 to 150℃. With a 1.1V supply voltage,the supply current is 43μA and the PSRR is 55dB at DC frequency. This bandgap reference has been verified in a UMC 0.18μm mixed mode CMOS technology and occupies 0. 186mm^2 of chip area.
文摘A new method,namely multiple point curvature compensation （MPCC）,is proposed for the design of a bandgap reference,and its design principles, theoretical derivation, and one feasible circuitry implementation are presented. Being different from traditional techniques, this idea focuses on finding multiple temperatures in the whole range at which the first order derivatives of the output reference voltage equal zero. In this way, the curve of the output reference voltage is flattened and a better effect of curvature compensation is achieved. The circuitry is simulated in ST Microelectronics 0. 18μm CMOS technology, and the simulated result shows that the average temperature coefficient is only 1ppm/℃ in the range from - 40 to 125℃.
基金Supported by National Natural Science Foundation of China(Grant Nos.51575087,51205041)Science Fund for Creative Research Groups(Grant No.51321004)+1 种基金Basic Research Foundation of Key Laboratory of Liaoning Educational Committee,China(Grant No.LZ2014003)Research Project of Ministry of Education of China(Grant No.113018A)
文摘Parts with varied curvature features play increasingly critical roles in engineering, and are often machined under high-speed continuous-path running mode to ensure the machining efficiency. However, the continuous-path running trajectory error is significant during high-feed-speed machining, which seriously restricts the machining precision for such parts with varied curvature features. In order to reduce the continuous-path running trajectory error without sacrificing the machining efficiency, a pre-compensation method for the trajectory error is proposed. Based on the formation mechanism of the continuous-path running trajectory error analyzed, this error is estimated in advance by approximating the desired toolpath with spline curves. Then, an iterative error pre-compensation method is presented. By machining with the regenerated toolpath after pre-compensation instead of the uncompensated toolpath, the continuous-path running trajectory error can be effectively decreased without the reduction of the feed speed. To demonstrate the feasibility of the proposed pre-compensation method, a heart curve toolpath that possesses varied curvature features is employed. Experimental results indicate that compared with the uncompensated processing trajectory, the maximum and average machining errors for the pre-compensated processing trajectory are reduced by 67.19% and 82.30%, respectively. An easy to implement solution for high efficiency and high precision machining of the parts with varied curvature features is provided.
基金Supported by the National Natural Science Foundation of China(61604109)the National High-Tech R&D Program of China(2015AA042605)
文摘A lowtemperature coefficient（ TC） bandgap reference（ BGR） with novel process variation calibration technique is proposed in this paper. This proposed calibration technique compensating both TC and output value of BGR achieves fine adjustment step towards the reference voltage,while keeping optimal TC by utilizing large resistance to help layout match. The high-order curvature compensation realized by poly and p-diffusion resistors is introduced into the design to guarantee the temperature characteristic. Implemented in 180 nm technology,the proposed BGR has been simulated to have a power supply rejection ratio（ PSRR） of 91 dB@100 Hz. The calibration technique covers output voltage scope of 0. 49 V-0. 56 Vwith TC of 9. 45 × 10^（-6）/℃-9. 56 × 10^（-6）/℃ over the temperature range of-40 ℃-120 ℃. The designed BGR provides a reference voltage of 500 mV,with measured TC of 10. 1 × 10^（-6）/℃.
文摘A novel curvature-compensated CMOS bandgap voltage reference is presented. The reference utilizes two first order temperature compensations generated from the nonlinearity of the finite current gain β of vertical pnp bipolar transistor. The proposed circuit, designed in a standard 0.18 μm CMOS process, achieves a good temperature coefficient of 2.44 ppm/℃ with temperature range from --40℃ to 85 ℃, and about 4 mV supply voltage variation in the range from 1.4 V to 2.4 V. With a 1.8 V supply voltage, the power supply rejection ratio is -56dB at 10MHz.
基金Supported by Scientific Research Project of Heilongjiang Health Commission,China,No.2020-141.
文摘BACKGROUND Myopia and high myopia are global public health concerns.Patients with high myopia account for 0.5%-5.0%of the global population.AIM To examine diopters,axial length(AL),higher-order aberrations,and other ocular parameters in Chinese children with myopia,to analyze the influence of structural parameters associated with myopia on visual quality,and to provide a theoretical basis for the prevention and treatment of childhood myopia and high myopia.METHODS This study included 195 children aged 6–17 years with myopia.The AL was measured with an ultrasonic ophthalmic diagnostic instrument,and the aberrations,corneal curvature(minimum K1,maximum K2,and average Km),central corneal thickness,anterior chamber depth,and anterior chamber angle were measured using a Sirius three-dimensional anterior segment analyzer.Using a standard formula,the corneal radius of curvature R(337.3/Km)and AL/R values were obtained.RESULTS The diopter of high myopia compared with low-middle myopia was correlated with age and AL(r=-0.336,-0.405,P<0.001),and AL of high myopia was negatively correlated with K1,K2,and Km(r=-0.673,-0.661,and-0.680,respectively;P<0.001),and positively correlated with age and the anterior chamber depth(r=0.214 and 0.275,respectively;P<0.05).AL/R was more closely related to diopter than AL in children with myopia,and 94.4%of children with myopia had an AL/R of>3.00.CONCLUSION The ocular structural parameters of children change because of different diopters.AL/R is more specific and sensitive than AL in evaluating the refractive status of myopia in children.An AL/R of>3.00 may be used as a specific index of myopia in children.There are differences in AL/R between high myopia and low-middle myopia,which can be used for the classification of ametropia.The degree of myopia has a certain influence on higher-order aberrations.
文摘The precision controlling technology is a key step for the modern ship construction, with the precision controlling of the ship-hull curvature as one of bottlenecks in shipbuilding, where the initial is to present a compensation value for the ship-hull plate precisely. The compensation value of the curvature plate is composed of two parts: the construction compensation, which results in the process of heating construction of curvature plate, and the assembling compensation, which results in welding ribbed stiffeners onto the curvature plate. Based on the developed computation system for the local contraction value, this paper presents a method to establish the experimented samples for the assembling compensation by means of numerical experiments, and another method to establish the practical mathematical model for the construction compensation of curvature plate. Furthermore, it introduces the experimental measuring method for the assembling compensation of the curvature plate, based on which the related database system has been developed. Numerical examples are analyzed to demonstrate the process to establish mathematical model for the assembling compensation values.
文摘A bandgap voltage reference is presented with a piecewise linear compensating circuit in order to reduce the temperature coefficient.The basic principle is to divide the whole operating temperature range into some sub ranges.At different temperature sub ranges the bandgap reference can be compensated by different linear functions.Since the temperature sub range is much narrower than the whole range,the compensation error can be reduced significantly.Theoretically,the precision can be improved unlimitedly if the sub ranges are narrow enough.In the given example,with only three temperature sub ranges,the temperature coefficient of a conventional bandgap reference drops from 1 5×10 -5 /℃ to 2×10 -6 /℃ over the -40℃ to 120℃ temperature range.
文摘A high precision high-order curvature-compensated bandgap reference compatible with the standard Bi-CMOS process,which uses a simple structure to realize a novel exponential curvature compensation in lower temperature ranges,and a piecewise curvature correction in higher temperature ranges,is presented.Experiment results of the proposed bandgap reference implemented with a 0.6-μm BCD process demonstrate that a temperature coefficient of 2.9 ppm/℃is realized at a 3.6-V power supply,a power supply rejection ratio of 85 dB is achieved,and the line regulation is better than 0.318 mV/V for 2.2-5 V supply voltage dissipating a maximum supply current of 45μA.The active area of the presented bandgap reference is 260×240μm;.
基金Project supported by the National Natural Science Foundation of China(No.61376032)
文摘A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate voltage｜VGS｜p of a PMOS transistor working in the saturated region. The second sub-reference is the weighted sum of gate-source voltages｜VGS｜n of NMOS transistors in the subthreshold region and the difference between two base-emitter voltages △VBE of bipolar junction transistors （BJTs）. The voltage reference implemented utilizing the proposed curvature compensation technique exhibits a low temperature coefficient and occupies a small silicon area. The proposed technique was verified in 0.18 μm standard CMOS process technology. The performance of the circuit has been measured. The measured results show a temperature coefficient as low as 12.7 pprrd /℃ without trimming, over a temperature range from -40 to 120℃, and the current consumption is 50 μA at room temperature. The measured power-supply rejection ratio （PSRR） is -31.2 dB @ 100 kHz. The circuit occupies an area of 0.045 mm2.
基金Project supported by the Fund of Liaoning Province Education Department(No.L2013045)
文摘A novel high-order curvature compensation negative voltage bandgap reference （NBGR） based on a novel multilevel compensation technique is introduced. Employing an exponential curvature compensation （ECC） term with many high order terms in itself, in a lower temperature range （TR） and a multilevel curvature compen- sation （MLCC） term in a higher TR, a flattened and better effect of curvature compensation over the TR of 165℃ （--40 to 125 ℃） is realised. The MLCC circuit adds two convex curves by using two sub-threshold operated NMOS. The proposed NBGR implemented in the Central Semiconductor Manufacturing Corporation （CSMC） 0.5 #m BCD technology demonstrates an accurate voltage of-1.183 V with a temperature coefficient （TC） as low as 2.45 ppm/℃over the TR of 165℃ at a -5.0 V power supply; the line regulation is 3 mV/V from a -5 to -2 V supply voltage. The active area of the presented NBGR is 370×180 μm2.
文摘A new low-voltage CMOS bandgap reference （BGR） that achieves high temperature stability is proposed. It feeds back the output voltage to the curvature compensation circuit that constitutes a closed loop circuit to cancel the logarithmic term of voltage VBE. Meanwhile a low voltage amplifier with the 0.5 μm low threshold technology is designed for the BGR. A high temperature stability BGR circuit is fabricated in the CSMC 0.5μm CMOS technology. The measured result shows that the BGR can operate down to 1 V, while the temperature coefficient and line regulation are only 9 ppm/℃ and 1.2 mV/V, respectively.
