To improve the performance of the micro-machined resonant pressure sensor and simplify its fabrication process, a novel structure is proposed in which the boron diffused silicon (up to 15um thickness) and the bulk silicon are used as the resonant beam and pressure membrane respectively. The structural parameters were optimized through FEM to achieve the better sensitivity, and the relationships between the structural parameters and the sensitivity were established. Moreover, the fabrication processes were discussed to increase the product rate and the pressure sensor with the optimal structural parameters was fabricated by the bulk silicon MEMS processes. In order to enhance the signal of the sensor and make the closed-looped control of the sensor easily, electromagnetic excitation and detection was applied. However there is so high noise coming from the distributing capacitances between the diffused silicon layer and electrodes that reduce the signal to noise ratio of the sensor. Through the analysis of the micro-structure of the sensor, the asymmetrical excitation circuit was used to reduce the noise and then the detection circuit was designed for this sensor. The resonator of the sensor was packaged in the low vacuum condition so that the high quality factor (Q) with about 10000 can be achieved. Experimental tests were carried out for the sensor over the range of -80kPa to 100kPa, the results show that the sensitivity of the sensor is about 20kHz/100kPa, the sensitivity is 0.01%F.S. and the nonlinearity is about 1.8%.

No abstract

No abstract

The electromagnetic susceptibility model of discontinuous microstrip circuits with the presence of a uniform plane incident wave is established. First, the analytical expressions are modeled as equivalent voltage and current sources for discussing the global effect of the incident plane wave on the associated interconnects. Then, these field-induced equivalent source expressions are incorporated into ADS circuit solver, and a fast model is established for analyzing the output responses of discontinuous microstrip circuits, such as the cross bend, the band-rejection filter and the single-stage amplifier. The corresponding simulation results from the proposed model are validated by comparing the results from both simulation and measurement. The results also show that the incident plane wave may influence the output terminal responses significantly, and the proposed approach would be an efficient method to solve the electromagnetic susceptibility problems associated with the discontinuous microstrip circuits.

A novel structure of micro-machined resonant pressure sensor with diffused silicon as the resonant beam is proposed in this paper. To improve the signal to noise ratio (SNR) of the sensor so as to realize the close-looped control of electromagnetic excitation and detection easily, the microstructure of the sensor was introduced and analyzed firstly. It is found that the co-channel interference resulting from the capacitance from the electrodes and diffused silicon layer of the sensor is the main noise resource. And then the equivalent circuit model for the micro-structure of the sensor is brought up, moreover the methods to reduce the co-channel interference were tried and discussed. Thus a novel measure with nonsymmetrical excitation was proposed. Experiments show that this measure can effectively eliminate the co-channel interference of the sensor and the SNR is improved from 1.53 to 35, which provide the effective ways to close-looped excitation and detection for the sensor.