A low-cost circuit for high-value resistive sensors varying over a wide range

Abstract

In this paper, a low-cost interface for high-value resistive sensors ranging from kΩ to GΩ is presented. The proposed circuit acts as a ‘resistance-to-period converter’ and overcomes limits of previously developed solutions due to sensor parasitic capacitance. Particularly, this circuit estimates sensor resistance over six orders of magnitude without changing any scaling factor and is able to quantify sensor parasitic capacitance, in the order of pF. Estimation errors, due to real electronic components, are taken into account. Experimental results, obtained by the realized prototype, show a good resolution and repeatability, always better than 0.05%. Thermal effects have been considered and experimentally evaluated from θ = 10 °C to θ = 60 °C.

Advanced interfaces for resistive sensors

“…By using the integrator architecture and a suitable reset circuit, it is possible to perform the R s estimation only during one phase of the integration (e.g., during the V int falling ramp) and to restart the measurement without the need to modify the sensor excitation voltage V exc (Depari et al ., 2006). This concept is illustrated by using the circuit in Fig.…”

Ultra-low power read-out integrated circuit design

“…The resistance-to-voltage method is biasing a fixed current source for the chemical CNTs based sensors [17][18][19][20], and then resistance change is converted to voltage change according to Ohm's law. The depicted architectures in [17][18][19][20] are limited for the relatively small resistance variations.…”

“…The depicted architectures in [17][18][19][20] are limited for the relatively small resistance variations.…”

A single-chip integrated interfacing circuit for wide-range resistive gas sensor arrays

“…In this sense, the use of oscillating circuits, performing a Resistanceto-Time (R-T) conversion, seems to be the best solution, because other kind of interfaces cannot ensure a wide output range without the use of either scaling factors or high-resolution pico-ammeters [19][20][21][22][23][24][25]. However, MOX sensors present also a parasitic capacitive component, C SENS , in parallel with the resistance, generally on the order of few picofarads, whose presence could affect the estimation of the resistive sensor component, if the excitation signal is an AC voltage.…”