A very high dynamic range interface circuit for resistive gas sensor matrix read-out

In this paper a low-cost integrated wide-range gas sensor interface based on a resistance-to-time converter is presented. The circuit in transistor level simulation achieves a linearity better than 0.5% over a range of 6 decades i. e. 1 kΩ ÷ 1 GΩ, without requiring any calibration or auto-ranging. The maximum sensing time is 0.5 s, while measuring the highest resistance value. The state-of-the-art of this measurement has been improved by extending the acceptable input resistance range, while lowering the maximum power consumption. More over, a very high linearity has been achieved by canceling the parasitic effects of the multiplexer addressing the sensor matrix.