During industrial signal acquisition, pressure sensors generate various inherent noises within their circuitry. These are inherent interferences of the device itself and cannot be completely eliminated, directly affecting measurement accuracy and signal stability.
Internally, noise in the circuit can be mainly categorized into seven types: thermal noise, shot noise, 1/f flicker noise, burst noise, parasitic resonance noise, leakage current noise, and mutual inductance coupling noise. These are the main internal causes of sensor data drift, fluctuations, and instantaneous jumps.
Thermal noise, also known as Johnson noise, is generated by the random thermal motion of electrons within the device. It increases with temperature and is a type of white noise across the entire frequency range. It causes signal baseline fluctuations and affects static measurement accuracy. Shot noise originates in the semiconductor PN junction. The discrete migration of charge carriers causes current fluctuations. The higher the operating current, the more significant the noise. After amplification by the amplifier circuit, it reduces the detection resolution of weak pressure signals.
1/f flicker noise is low-frequency noise. Its power increases as the frequency decreases. It is mostly caused by chip surface defects, material inhomogeneity, and poor contact. It is the main reason for zero-point drift and slow fluctuations in steady-state data during long-term sensor operation.
Popping noise, commonly known as popcorn noise, is caused by semiconductor lattice defects and impurity inhomogeneity. It manifests as irregular, sudden current pulses, causing instantaneous data jumps and easily leading to misjudgments in control systems.
Parasitic resonance noise originates from the parasitic inductance and capacitance of PCB circuits and components. During high-frequency operation, it forms a resonant circuit, causing waveform distortion and dynamic response inaccuracy, severely affecting detection accuracy under conditions of rapid pressure fluctuations. Leakage current noise is caused by unstable leakage current resulting from insulation aging and moisture accumulation. This leakage current is superimposed on the effective signal, increasing measurement errors, and is particularly prominent in harsh industrial environments.
Mutual inductance coupling noise is crosstalk generated by the mutual inductance coupling of magnetic fields between adjacent circuits and components within the circuit. It is significant in high-density PCB circuits, causing output signal fluctuations and decreased stability. These seven noise sources cover all interference sources under various operating conditions. In practical applications, noise can be suppressed by optimizing wiring, selecting low-noise components, strengthening insulation, and using temperature control for noise reduction, effectively improving the detection stability and accuracy of pressure sensors.
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