Sensor Signal Conditioning Circuits, Electromagnetic Compatibility Study

Sensor is one of the crucial technologies in information era. It is a significant manner to obtain accurate and dependable information. Sensor technique, which make use of various functional materials to carry out information detect into effect, is a synthetic technology. It is one of basic techniques to realize information in the contemporary area of science and technology.In general, sensor is composed of sensitive organ, transductional element and other assistant component in sensor technology. Signal conditional and transform circuit and auxiliary power are also considered as parts of sensor occasionally. In sensor circuit, various signals need to be transformed each other for unite application among element which have different input and output signal. Signal conditional circuit need to be used for noise suppression and signal transformation. The performance of that circuit is unusual important to sensor system of precision, stability and so on. It is very easy for exoteric interfere coupling to the circuit affect useful signal, because signal conditional circuit is relatively complex which deal with relatively weak signal and need to realize signal transformation. Infinitesimal disturbance of environment may cause great error or absolute wrong to output. The interference between components in the circuit is also serious. The EMC of signal conditional circuit is a significant composition of sensor technology.The main thesis of this paper was the EMC problems of signal conditioning circuit on PCB, because a large number of signal conditioning circuits are realized via print the circuit on PCB at present. The basic principles of EMC, and related to standards and norms were first introduced in this paper. After model and analysis of various coupled issues started with the three elements of EMI, the software which was used to analyzed EMC problems of signal conditioning circuit was realized here. The main calculation type such as crosstalk between the wire, shielded cable crosstalk, shielding effectiveness, field coupled to the wire, aperture leakage field coupled to the line and transfer impedance of cable are included in the software. Details of the classification are showed in the categories map of the structure of the framework in chapter V.The component which was often used in design of signal conditional circuit was analyzed in EMC. The technique for suppress interference which was often adopted in design of those circuit was introduced in this paper. A PCB of signal conditioning circuit was designed in consider of EMC. The signal conditioning circuit was used in piezoresistive sensors. MAX1450 was used in this design.