The work is devoted to the problem of signal transducers of high-sensitivity differential temperature sensors. The conducted studies have shown that the scheme of the signal converter with the stabilization of the total emitter currents of a transistors pair is characterized by a combination of high sensitivity and stability of the steepness of a transformation function. In particular, as compared to the circuit with the stabilization of the collector current of a reference transistor, the instability of steepness is reduced 20-fold. The research of the developed signal converters and their parametric analysis was carried out on the basis of transistors SPICE models.
For the number of modern sensors problems, in particular in micro and nanocalorimetry, a combination of high resolution of measurement of differential temperature and the speed of such measurement is necessary. Obviously, these requirements are inherent in the contradiction, i.e. increasing the speed leads to an inevitable loss of measurement accuracy. To eliminate this contradiction, the scheme of the signal converter on the basis of an integrator, which allows increase the resolution of the temperature difference measurement, is proposed.
In the schemes of the signal converter of differential temperature and the integrator, the high-precision operational amplifier of series AD8551 / AD8552 / AD8554 have been used. They operate on principle of the signal modulation-demodulation, which allows reach the minimum values of the bias voltage and its instability of 0.005 mV/°C. The characteristic relationship between accuracy and measurement time on the basis of the high-precision micro converter ADuC834 based on 24-bit sigma-delta (S-D) ADC used in the developed sensor of differential temperature is considered.
Experimental results of the developed sensor investigation have underlined the significant exactness: depending on the ADC range, the non-reproducibility of the voltage measurement is within ± 1 (10) μV, which corresponds to the resolution of the temperature measurement ±(10-4…10-3)°C.
[1] M. Pertijs, J. Huijsing, Precision temperature sensors in CMOS technology. Springer Science & Business Media, 2006.
[2] M. Pertijs, A. Niederkorn, X. Ma, “A CMOS smart temperature sensor with a 3σ in accuracy of ±0.5°C from -50°C to 120°C”, IEEE Journal of Solid-State Circuits, vol.40, iss.2, p.454-461, 2005.
[3] W. Wuicik, R. Holyaka, Z. Hotra et al, Analogue microprocessor measuring and sensory devices. Lviv. Ukraine: Publ. house Lviv Polytechn. Nat. Un., 1999.
[4] O. Boyko, R. Holyaka, Z. Hotra, “Functionally integrated sensors on magnetic and thermal methods combination basis”, in Proc. 14th Int. Conf. on Adv. Trends in Radioel., Telecom. Comp. Eng., Lviv-Slavske, Ukraine, 2018, pp. 697-701.
[5] C. Sosna, R. Buchner, W. Lang, “Temperature Compensation Circuit for Thermal Flow Sensors Operated in Constant-Temperature-Difference Mode”, IEEE Trans. on Instr. and Meas., vol.59, iss.6, p.1715-1721, 2010.
[6] Z. Hotra, V. Pavlov, R. Holyaka et al, Microelectronic signal converters of thermal flow sensors, Vinnytsya, Ukraine: VNTU, 2012.
[7] R. Behme, D. Brooke, “Heat of Fusion measurement of a low melting polymorph of carbamazepine that undergoes multiplephase changes during DSC analysis”, J. Pharm Sci., vol.80, iss.10, p.986-990, 2006.
[8] B. Cassel, R. Packer, Modulated Temperature DSC and the DSC 8500: A Step Up in Performance. Perkin Elmer Inc. [Online]. Available: https://www.perkinelmer.com/lab-solutions/resources/docs/TCH_ModulatedTe... DSC_009122B_01.pdf.
[9] C. Barreneche, A. Solé., L. Miró, et al, “New methodology developed for the differential scanning calorimetry analysis of polymeric matrixes incorporating phase change mate-rials”, Meas. Sci. and Techn., vol.23(8), p.085606-085610, 2012.
[10] A. Elhissi, M. O'Neill, W. Ahmed, K. Taylor, “High-sensitivity differential scanning calorimetry for measurement of steroid entrapment in nebulised liposomes generated from proliposomes”, Micro & Nano Letters, vol.6(8), p.694-697, 2011.
[11] L. Kunal, Highly sensitive nanocalorimeter. The laureates of nano ART 2013. Fondation Nanosciences. http://www.fondation-nanosciences.fr/ RTRA/en/ 659/2013-nanoart-laureates.html.
[12] Nano DSC technology. TA Instruments Microcalori-metry, 2012. [Online]. Available: http:// www.tainstruments .com.
[13] F. Mohammadi, S. Attar, “Development of an electrothermal simulation tool for integrated circuits: Application to a two-transistor circuit”, Can. Journ. El. and Comp. Eng., vol.33(3/4), p.191-200, 2008.