Working principle of diffused silicon pressure transmitters

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A diffused silicon pressure transmitter consists of a sensor and a signal processing circuit. The sensor is responsible for converting the pressure signal of the physical quantity to be measured at the work site into a voltage signal ； The signal processing circuit is responsible for transforming the voltage signal output by the sensor through amplification and signal processing, so as to output a standard signal. It is widely used in various industries due to its high measurement accuracy, fast dynamic response, ability to output DC signals, good linearity, wide operating temperature range, light weight, small size, and simple structure. Diffusion silicon pressure sensors are based on single-crystal silicon; they utilize advanced ion implantation and micro-mechanical processing techniques to create silicon sensing elements featuring a Wheatstone bridge and a precise mechanical structure. The pressure to be measured acts on the silicon sensor element via the pressure interface, enabling a linear conversion between the applied pressure and the output signal; a laser-tuned thick-film resistor network compensates for the temperature behavior of the sensor element. Based on the piezoresistive effect of single-crystal silicon, an elastic component is fabricated in a specific direction using advanced processing techniques; four strain resistors with equal resistance values, produced via integrated circuit technology and placed at appropriate positions on this component, are connected to form a Wheatstone bridge. The pressure of the medium under test acts directly on the diaphragm of the sensor (made of stainless steel or ceramic), causing the diaphragm to undergo a slight displacement that is proportional to the pressure of the medium. When the medium pressure passes through the stainless steel isolation diaphragm and reaches one side of the diffused silicon diaphragm via sealed silicone oil, the reference pressure (atmospheric pressure or sealed pressure) acting on the other side contributes to compressing one side of the diaphragm while stretching the other side. This pressure difference causes the bridge to become unbalanced, resulting in a signal that corresponds to the change in pressure. In the circuit section, the Wheatstone bridge is powered by a constant current supply to ensure that the output is not affected by temperature. The output signal from the bridge is amplified by a differential normalization amplifier, and then converted into a current through a V/I converter. This current undergoes compensation via a nonlinear correction circuit, resulting in a standard 4-20 mA ADC signal whose value is linearly related to pressure changes. Jiangsu Huike Automation Instrument Co., Ltd. offers you professional advice on product selection as well as reliable products. If you have any questions, feel free to call us; we will assign professional technicians to assist you.