METROLOGICAL ANALYSIS OF CHARGE TRANSFER CAPACITIVE TRANSDUCER IN THE PRESENCE OF RESISTANCE

Yıl 2012, Cilt: 2 Sayı: 3, 288 - 292, 01.12.2012

Plamen Nıkovskı

Öz

One of the major tasks in the design of measuring transducers is improving their accuracy in real conditions. Above all, this problem makes it necessary to evaluate the impact that various non-idealities have on the work of the measuring device. This study points that the presence of active resistance in the input of capacitive transducers, realizing the charge-transfer method, influences the measured result. With a configuration, composed of four analogue switches, the magnitude of the occurring in this case additional error depends on: the value of resistance in the input; the value of the capacity, which is the object of the measurement; the frequency and the phase offset of the clock signals, controlling the switches. The conditions under which error does not exceed 0,1% have been defined and a simple equation, by which its value can be assessed in the general case, has been validated. Presented results are useful in the design and implementation of industrial capacitive transducers

Anahtar Kelimeler

Capacitive transducer, resistance, methodological error

Kaynakça

• Webster J., Measurement instrumentation and sensors handbook, CRC Press LLC, p.2587, 1999.
• Huang S., A. Stott, R. Green et al., Electronic measurement of low value capacitance, Sci. Instruments, Vol. 21, pp.242-250, 1988.
• Toth F., A design methodology for low- cost, high-performance capacitive sensors, Delft University -Netherlands, p.152, 1997.
• Willem de Jong G., Smart capacitive sensors - physical, geometrical and electronic aspects, Delft University -Netherlands, p.313, метрологични капацитивни преобразователи с прехвърляне на заряд при наличие на фазово-константен елемент във входната верига, Дисертация за присъждане на образователна и научна степен "Доктор", ТУ-София, стр.128, 2011.
• Baxter L., Capacitive sensors, John Wiley and Sons, p.320, 1996. for industrial
• Никовски Пл., Подобряване на характеристики на измервателни Фархи С., Г. Ненов и др., Практически схеми с превключваеми кондензатори, Издателство Техника, стр.254, 1987.
• Philipp H., Charge transfer sensing, Sensor Review, Vol.19, No2, pp.96-105, 1999.
• Philipp H., The charge transfer sensor, Sensors - The Journal of Applied Sensing Technology, Vol.13, No.11, 1996.
• Cheng L., H. Zhang, Q. Li, Design of a capacitive flexible weighing sensor for vehicle WIM system, Sensors, No.7, pp.1530-1544,
• Hu X., M. Katsouros, W. YANG et al., Further capacitance measuring circuit used with tomography sensors, Sensors & Transducers Journal, Vol.80, Issue 6, 2007, pp.1246-1256.
• AN 367, Eeffects of ESD protection devices on capacitive sensing performance. – application note, Silicon Laboratories Inc., pp.6, 2001.
• Reverter F., Ò. Casas, Direct interface circuit for capacitive humidity sensors, Sensors and Actuators A 143, p.315-322, 2008.
• Carrara С., F. Gürkaynakb, C. Guiduccic, et al., Interface Layering Phenomena in Capacitance Detection of DNA with Biochips, Sensors and Transducers Journal, Vol 76, p. 977, 2007.
• Krommenhoek E., J. Gardeniers, J. Bomer, et al., Monitoring of yeast cell concentration impedance sensor, Sens. Actuators B 115, p.384–389, 2006.
• Брандински К., Ж. Георгиев и др., Теоретична електротехника II част, Кинг, стр.495, 2005. of charge/discharge using a micromachined