A Dual-mode Flow Measurement System for Large Sensing Range with High Accuracy

This paper presents a smart system for large flow range measurement, consisting of a dual-mode MEMS flow sensor and the readout IC. During high flow rate (> 25 m/s), the output of the dual-mode sensor is directly digitized by a switched-capacitor incremental delta-sigma ADC with 12-bits resolution due to its large output amplitude. While in low flow rate, the sensor output is first amplified by a capacitively-coupled instrumentation amplifier (CCIA) before digitization. A comparator is employed to enable a dynamic switching between two operation modes based on the flow rate. The readout IC can handle a large input up to 800 mV and consumes a current as low as 114 μA. The simulation results show the measurement system achieves a maximum sensing flow rate of 73 m/s while contributes a maximum measurement error rate of 300 ppm which is considerably lower than the industry standard of 3%.