Analog Linearization of Resistance Temperature Detectors (RTD) Using the Intrinsic Curvature of BandGap Voltage References

• Autor(a) principal: Carvalhaes-Dias, P.
• Data de Publicação: 2018
• Outros Autores: Ferreira, I. P., Oliveira Morais, F. J. [UNESP], Caparroz Duarte, L. F., Siqueira Dias, J. A., Yurish, S. Y.
• Tipo de documento: Artigo de conferência
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/209444
• topic: RTD; Bandgap curvature; Brokaw cell; Linearization; Temperature sensors

Although resistance temperature detectors (RTD) are more linear than thermocouples, they present second and third order non-linearities, and a linear signal processing circuit which converts the voltage on a Pt-100 RTD to an output voltage with 10 mV/degrees C presents a maximum non-linearity error of 1.07 degrees C (10.7 mV) in the 0 to 85 degrees C temperature range. Although these non-linearities can be corrected digitally, there are cases where a simple analog linearization can be used with advantages. In this work we present an analog linearization technique that uses the output of a conventional Brokaw bandgap cell as the reference voltage of a differential instrumentation amplifier. The intrinsic curvature of the bandgap voltage reference, caused by the non-linear variation with temperature of the VBE of a transistor, creates a compensation voltage that can reduce the non-linearity of the signal processing circuit by one order of magnitude (down to approximately 0.14 degrees C) in the same temperature range.