Design and Optimization of Interface Circuits of MEMS Thermal Wind Speed Sensor Based on a Macro Model

In this paper, interface circuits of MEMS thermal wind sensor that compensating system temperature drift are designed based on a macro model. The macro model realizes the co-simulation of the sensor and circuits by coupling thermal field, flow field and electric field with the combination of linear time irrelevant (LTI) reduced-order model (ROM) method, convective heat transfer formula and Verilog-A, temperature effects on the sensor are also taken into account. Based on the model, a constant temperature difference (CTD) control circuit is designed and optimized, which consists of a two-Wheatstone bridges structure and two amplifiers in general. It compensates the temperature drift caused by the mismatch of the temperature coefficient of the heating resistor and the ambient temperature measurement resistor in CTD control. To solve the temperature drift problem of the sensor output voltage, a compensation circuit based on a reference voltage generation circuit with adjustable temperature coefficient is designed to meet the needs of integration and low power consumption instead of using micro control unit (MCU) for software compensation. The error of measured wind speed is less than 0.8m/s. The results shows that the proposed circuits meet the requirements of the sensor system, and the design flow with the aid of the macro model has high efficiency and convenience.