Fml. Vandergoes et Gcm. Meijer, A UNIVERSAL TRANSDUCER INTERFACE FOR CAPACITIVE AND RESISTIVE SENSOR ELEMENTS, Analog integrated circuits and signal processing, 14(3), 1997, pp. 249-260
This paper presents a new universal transducer interface. This interfa
ce, which is read out by a microcontroller, services the following sen
sor elements: capacitors, platinum resistors, thermistors, resistive b
ridges and potentiometers. The A/D conversion is based on a first-orde
r oscillator A combination of classical and some new measurement techn
iques has been applied on a single chip to obtain high accuracy, good
long-term stability and a reduction of the effects of interference and
parasitic elements. The circuit has been fabricated in a 0.7 mu m CMO
S process. The main test results are: an accuracy of 10-15 bits and a
resolution up to 16 bits while the measurement time is in the range 1-
100ms. These results hold over the temperature range -20 degrees-C to
80 degrees-C. Calibration of the electronic part is not required. The
number of external components has been kept to a minimum.