Key Engineering Materials Vols. 609-610

Abstract: An ultrasonic anemometer using TDC-GP2 high-accuracy time measuring chip is studied in this paper, the design of software and hardware parts and principle of flying time measurement using TDC-GP2 chip are also discussed in detail. Under this scheme, a prototype has been fabricated, with simpler circuit architecture. A wind tunnel experiment of the prototype was conducted, the test result shows that the ultrasonic anemometer can measure wind speed up to 39.9m/s, and the measurement error does not exceed 0.3m/s when wind speed is below 10m/s, or 3 percentage when its above 10m/s. Wind directions vary from 0 to 359 degree can be detected with accuracy of 3 degree.

Abstract: As AFM tip approach speed is one of the key factors for AFM industrial on-line detection application, a sectional fast tip approach method composed of rough approach and mild approach processes is introduced here. In rough approach process, AFM tip can be approached by step motor to certain distance upon the sample surface with high speed, as a homemade dual-channel reflective intensity modulated fiber optic displacement sensor (DC-RIMFODS) can be integrated to AFM scan head easily to detect the stop position. While continued with mild approach process after rough approach, step motor can run slowly with a common PI feedback controller for Z scanner to make the tip get in touch with sample surface softly. Experimental results show that with the well-defined fiber optical sensor positioning accuracy and repeatability, the tip-sample distance can be limited in certain range after rough approach with 1mm/s high speed, and the whole AFM tip approach process can be finished in 20s by continuing with mild approach, while the initial tip-sample distance is about 10mm.

Abstract: This paper presents a design of fractional-N frequency synthesizer with low dithering, which is fabricated in a 130nm CMOS process. A 3^rd-order delta-sigma modulator is based on digital multi-stage noise shaping (MASH) structure with its second and third stage dithered by 7-bit linear feedback shift register (LFSR) was designed for the frequency synthesizer, and a long word is used for the first modulator in the MASH structure. The simulation result of the whole frequency synthesizer shows that it can output two-way I/Q signal between 2.28GHz and 2.53GHz, and its spurs are lower than-75dBc.

Abstract: The fabrication of butterfly-shape resonator is key for high precision resonator, for requiring suspend on the silicon substrate. This paper is focused on the technology of making butterfly-shape resonator. the variety of structure design can be used to make butterfly-shape resonator have been analyzed, the structure of butterfly-shape resonator is obtained, and for reducing the etch surface roughness, KOH etching conditions, such as composition, concentration, and temperature of etch solution, have been done. Combining with above testing results, the structure design and optimization KOH etching technology are obtained ,based on the technology, using the boron etch stop technique , the silicon butterfly-shape resonator has been done, it can be used effectively in the fabrication of the silicon resonant sensor.

Abstract: Aimed at the dynamic pressure measurement, this paper presents a pressure sensor based on MEMS technology. An absolute pressure sensor is in one silicon chip of which the size is 3.05mm×3.05mm with the diaphragm thickness of 890μm. We combine Piezoresistive Bridge with signal conditioning chip, and design a gain adjustable, high sensitivity dynamic pressure sensors. By changing the depth of the sensor in water, the resulting change in the resistor signal is then used to calculate the depth of the water. The experimental results show that the measuring accuracy can reach 2×10^-4V per 1mm (water depth). The design of the hardware circuit was simple, flexible configuration, versatile features. It was found that the pressure sensor bad a linear response to pressure as expected, and was more sensitive than conventional resistor sensor. Sensor, small size, high sensitivity, will be providing a better way to measure eye aqueous humor.

Abstract: This paper deals with design and simulation of vibratory ring gyroscope which has good performance as resisting vibration, resisting impact, small temperature drift because of the inherent symmetry of structure. The good performance of gyroscope has verified by detailed modeling and simulation. The manufacture of gyroscope using wafer level vacuum packaging technology making the gyroscope has high quality factor .At last we test the gyroscope and the Q factor is 20300 by detecting the resonant state of the gyroscope.

Abstract: This paper presents a laterally driven resonant barometric pressure sensor fabricated using SOI-MEMS technology. In this device, pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in H style doubly-clamped micro beams, leading to resonant frequency shift. In device fabrication, SOI-MEMS fabrication processes were utilized, where a new modified buffered hydrofluoric acid (BHF) solution was used to remove the buried oxide layer and release the suspended resonant beams. Experimental results recorded a device resolution of 10Pa, a nonlinearity of 0.04% and a temperature coefficient of-0.04% F.S/°C in the range of-40°C to 30°C. The long-term stability error of the proposed device was quantified as 0.05% F.S over the past 3 months.

Abstract: Based on the analysis of inclination principle Using MEMS acceleration sensor,we design the divided voltage circuit and regulating circuit.This article based on the MCU minimum system,using MEMS acceleration sensor for development and application, and the angle information can be displayed by LCD or PC.The inclination measurement precision can reach ± 0.2 °,so it can be used for measuring the pose of guided shell , airplane, missiles and other aerocraft construction, also can be used in geological exploration and other fields.

Abstract: Zero bias is an important performance index of MEMS accelerometerscope. Based on the large amount of given accelerometer experiments, we study zero bias of random error properties, temperature characteristic, large overload environment variation, and then calculate MEMS accelerometer bias, bias stability, zero bias repeatability. Through least-square method,we fit temperature scale factor and temperature bias of MEMS accelerometer. The experimental results show that the compensation method has the advantages of simple operation, effectively compensation for measuring error of MEMS accelerometer which is induced by temperature, and has strong engineering using value.

Abstract: A wide range pressure sensor is designed based on the theoretical basis of LC series resonance circuit model to realize the wireless passive measurement in the harsh environment, such as high temperature and high pressure. The capacitive pressure sensitive device is devised by the technology of high-temperature co-fired ceramics (HTCC) to form nine density cavities in zirconia ceramic substrates, and thick film technology to print capacitance plates and planar spiral inductors. The theoretical calculation and simulation analysis of the designed sensor are made respectively under high pressure (10MPa) and temperature (600 °C), the results of which verify the feasibility of the design in a wide range of pressure for high-temperature applications, and provide the reliable theory basis for the fabrication of wide range pressure sensor.