Question -- Principle of single-crystal silicon resonant transmitters

http://www.shiyou365.com/js_show.asp?newsId=3046 – there is a detailed explanation there

A single-crystal silicon resonant sensor is a single-crystal silicon chip on which microelectromechanical processing techniques are used to create two identical H-shaped resonant beams, which vibrate at a certain frequency. Its resonant frequency depends on the length and tension of the beam; the length of the beam is fixed, while the tension changes with pressure. Thus, the change in pressure is converted into a change in frequency; frequency difference technology is applied to the differential pressure, and the frequency difference signal is directly output to the CPU for processing and A/D conversion. 1. High precision: Thanks to the use of single-crystal silicon resonant sensors, their excellent performance ensures high measurement accuracy; the precision of this transmitter can reach ±0.065%, a level that is unattainable by other transmitters.       2. Good stability: Since the circuit incorporates a characteristic correction memory, the temperature and static pressure data collected are processed by the CPU to correct any measurement drift that may occur. At the same time, the intelligent converter uses large-scale integrated circuits and transforms the amplifier into an AISC type, reducing the number of components and enhancing the reliability of the amplifier itself, thereby ensuring that the instrument possesses very high stability and repeatability. Our factory has been using EJA smart transmitters since 1997, and to date there has been almost no need for maintenance; neither the zero point nor the range shifts, which makes them very popular among those responsible for transmitter maintenance.       3. Good hydrostatic properties: Due to the precise manufacturing process of the two resonant beams, their dimensions are exactly the same and they lie on the same surface; as a result, the frequency changes that occur under pressure are identical, with no variation in their difference. Therefore, the introduction of a static pressure gauge has almost no impact on the measurement, ensuring its accuracy.       4. Good unidirectional compression performance: The transmitter has an excellent ability to withstand repeated compressive forces on the high-pressure and low-pressure sides; this value can reach up to 16 Mpa. Its compression time can reach 30 seconds. Its advantage is that it eliminates the need for a balance valve during installation, saving on costs. On the other hand, it can prevent the transmitter from being damaged due to unilateral pressure caused by misoperation or blockage of the pressure guiding tube, thus avoiding losses for the enterprise.       5. Wide measurement range: Within its typical operating range, the EJA smart transmitter has a span ratio of 100:1; it can also be 30:1 to 40:1. However, in addition to assessing whether a transmitter has a wide measurement range, it is also necessary to consider the materials used for various components of the transmitter as well as whether many additional specifications allow the device to be used for multiple purposes. The EJA transmitter excels in this regard: the materials used for its contact parts, the body, and the exhaust valve are all JIS SUS316, while the diaphragm box is made of JIS SUS316L (and the diaphragm itself is made of Hastelloy C-276). Such highly corrosion-resistant materials enhance the versatility of the transmitter. Therefore, a wide range ratio, versatile materials for the liquid-contacting components, and a reduction in additional specifications enhance the practicality and versatility of the transmitter, bringing convenience to designers and users. At the same time, it also reduces the number and variety of auxiliary tables, thereby cutting maintenance costs for enterprises.       6. Convenient configuration capabilities and self-diagnosis functions The EJA transmitters feature intelligent communication capabilities, allowing remote adjustment of parameters such as range, engineering units, calculation functions, damping time, and tag numbers via handheld terminals like BT200/HART375 or DCSs (with I/O cards that have field communication functions). It is also possible to perform fault diagnosis and zero-point adjustment on the transmitter ； Additionally, the transmitter’s self-diagnosis function can display its operating status and fault information, thereby assisting maintenance personnel in analyzing and diagnosing faults.

Emerson’s Rossmont 3051 model can achieve an accuracy of ±0.05%