Intelligent Sensor Systems, Electromagnetic Compatibility Design

As the development of technology, the electro-magnetic environment is becoming more and more complex, so the requirement of the interference suppression also enhances. As one of the basis of the information technology, the electro-magnetic problem for the intelligent sensor systems is becoming more and more important.Aiming at this problem, this article analyzed and simulated each part of the intelligent sensor systems, the driving circuits of the sensor, the signal conditioning circuits, the power circuits and studied the noise suppression. With these methods and results above, a PCB was designed.The constant voltage and constant current driving methods for the pressure sensors were studied, the differences between them were analyzed and the results showed that the constant current driving method was a better one for high precision situations.The differential amplifier and instrumentation amplifier were studied, theoretic analysis and simulations were made for the influencing factors of their CMRR and input resistors, and the results showed that the instrumentation amplifier formed by three operational amplifiers could satisfy the requirement of high CMRR and input resistors and it suits the signal conditioning circuits.The power circuits were studied, the effect of the value of the filtering capacitance on the harmonic current was analyzed and simulated and the results showed that the value of the filtering capacitance needed the consideration for both the ripple voltage and the harmonic current. The series stablizing power circuits and the EMI filters were studied, and the simulation results showed that the interference suppression ability of the EMI filters was very strong. The noise and noise suppression methods were studied.With these suppression methods and the rules for scheme designs, component choices, layout and routing in EMC designs for PCB, an interface circuit for MPX2010 silicon piezo-resistive pressure sensor has been designed, and circuit simulations and routing were also made.