Square-rooting and absolute function circuits using operational amplifiers

Riewruja, Vanchai; Kamsri, Thawatchai

doi:10.1049/iet-cds.2008.0140

Cited by 10 publications

(6 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this study, a bipolar opamp was used for experimental implementation. From Figure 2 a, the supply currents i SP and i SN of the opamp can be expressed as [ 29 , 30 , 31 ]

and

where I B and I S denote the quiescent current and the bias current of the class-AB output state of the opamp, respectively.…”

Section: Principlementioning

confidence: 99%

“…Therefore, the error of the resolver signal on the secondary winding side because of temperature can be extracted from the primary winding side. In this study, the error in the resolver signal due to the temperature effect was investigated from the current flowing through the primary winding of the resolver using the opamp supply-current-sensing technique [ 29 , 30 , 31 ]. The amplitude variation in the resolver signal due to the temperature effect was determined and compensated for using subtract-and-sum topology.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Temperature-Compensation Technique for Improving Resolver Accuracy

Petchmaneelumka

Riewruja

Songsuwankit

et al. 2021

Sensors

View full text Add to dashboard Cite

Variation in the ambient temperature deteriorates the accuracy of a resolver. In this paper, a temperature-compensation technique is introduced to improve resolver accuracy. The ambient temperature causes deviations in the resolver signal; therefore, the disturbed signal is investigated through the change in current in the primary winding of the resolver. For the proposed technique, the primary winding of the resolver is driven by a class-AB output stage of an operational amplifier (opamp), where the primary winding current forms part of the supply current of the opamp. The opamp supply-current sensing technique is used to extract the primary winding current. The error of the resolver signal due to temperature variations is directly evaluated from the supply current of the opamp. Therefore, the proposed technique does not require a temperature-sensitive device. Using the proposed technique, the error of the resolver signal when the ambient temperature increases to 70 °C can be minimized from 1.463% without temperature compensation to 0.017% with temperature compensation. The performance of the proposed technique is discussed in detail and is confirmed by experimental implementation using commercial devices. The results show that the proposed circuit can compensate for wide variations in ambient temperature.

show abstract

“…In this study, a bipolar opamp was used for experimental implementation. From Figure 2 a, the supply currents i SP and i SN of the opamp can be expressed as [ 29 , 30 , 31 ]

and

where I B and I S denote the quiescent current and the bias current of the class-AB output state of the opamp, respectively.…”

Section: Principlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Temperature-Compensation Technique for Improving Resolver Accuracy

Petchmaneelumka

Riewruja

Songsuwankit

et al. 2021

Sensors

View full text Add to dashboard Cite

show abstract

“…rooting is a significant mathematical function finding applications in electrical and electronic circuit analysis and design (Kamsri et al, 2008;Riewruja and Kamsri, 2009;Rungkhum et al, 2007; available at: https://electronics.stackexchange.com/questions/78294/ extracting-the-square-root-of-a-voltage). Square rooting of a voltage or current function can be considered as a typical example of a temporal arc function in which the function possesses more than one value for any given time argument.…”

Section: Time Domain Polynomialmentioning

confidence: 99%

A transform of univariable time domain polynomial for extraction of temporal arcs

Thankappan¹

2020

COMPEL

View full text Add to dashboard Cite

Purpose This paper aims to present a special transformation that is applied to univariable polynomials of an arbitrary order, resulting in the generation of the proposed offset eliminated polynomial. This transform-based approach is used in the analysis and synthesis of temporal arc functions, which are time domain polynomial functions possessing two or more values simultaneously. Using the proposed transform, the submerged values of temporal arcs can also be extracted in measurements. Design/methodology/approach The methodology involves a two-step mathematical procedure in which the proposed transform of the weighted modified derivative of the polynomial is generated, followed by multiplication with a linear or ramp function. The transform introduces a stretching in the temporal or spatial domain depending on the type of variable under consideration, resulting in modifications for parameters such as time derivative and relative velocity. Findings Detailed analysis of various parameters in this modified time domain is performed and results are presented. Additionally, using the proposed methodology, the submerged value of any temporal arc function can also be extracted in measurements, thereby unraveling the temporal arc. Practical implications A typical implementation study with results is also presented for an operational amplifier-based temporal arc-producing square rooting circuit for the extraction of the submerged value of the function. Originality/value The proposed transform-based approach has major applications in extracting the values of temporal arc functions that are submerged in conventional experimental measurements, thereby providing a novel method in unraveling that class of special functions.

show abstract

“…(13) Thus, the displacement signal can be extracted from the LVDT output signal using a synchronous demodulator based on a peak amplitude finder or an analog multiplier. (13)(14)(15)(16)(17) The transfer characteristic of the LVDT provides a nonlinear behavior for the moving core that varies in the maximum stroke range, which can be expressed as a third-order function of the core position. (2,12,18) Note that the linear operating range of the LVDT exists only in the narrow range close to the zero crossing.…”

Section: Introductionmentioning

confidence: 99%

Linear-range Extension for Linear Variable Differential Transformer Using Binomial Series

Petchmaneelumka¹,

Songsuwankit²,

Tongcharoen³

et al. 2020

Sensors and Materials

View full text Add to dashboard Cite

Keywords: linear variable differential transformer, inductive transducer, linear range extension, binomial series, operational amplifier, analog multiplierThe linear-range extension technique for a linear variable differential transformer (LVDT) is described in this paper. Generally, the LVDT has a narrow linear operating range caused by its nonlinear transfer characteristic. To extend the linear operating range, the nonlinear behavior of the LVDT must be adjusted. In this paper, the circuit building block providing the LVDT inverse transfer characteristic using binomial series approximation is proposed for linearizing the nonlinear behavior of the LVDT. The third-order inverse transfer characteristic of the LVDT is synthesized from analog multipliers and a difference amplifier comprising an operational amplifier (opamp). All active devices used in this study are commercially available. Therefore, the attraction of the proposed technique is in the simple configuration and low cost, making it suitable for an embedded measurement system. The performance of the proposed technique is discussed in detail. Simulation and experimental results confirming the performance are also included. As a result, the linear range of the commercial LVDT used in this study can be extended more than 500%. The full scale error of the measured value is about 0.23% over the entire operating range.

show abstract

Square-rooting and absolute function circuits using operational amplifiers

Cited by 10 publications

References 13 publications

A Temperature-Compensation Technique for Improving Resolver Accuracy

A Temperature-Compensation Technique for Improving Resolver Accuracy

A transform of univariable time domain polynomial for extraction of temporal arcs

Linear-range Extension for Linear Variable Differential Transformer Using Binomial Series

Contact Info

Product

Resources

About