Study Of Environmental Electromagnetic Interference Characteristics Of The Saw Filter

Surface acoustic wave(SAW) device is an advanced analog signal processing device by means of acoustic wave character. Since SAW technologies is applied thirty years ago, SAW devices accelerate growth because of their broad use and in the meantime their performance are raised constantly. Because its high performance, light weight and good consistency, it is widely used in modern microwave communication and radar system and so on. With SAW filters and amplifiers used in electronic warfare, radar and communication system, electromagnetic interference (EMI) of SAW devices is evident day and day. So SAW device technologies of the EMI and electromagnetic compatibility in its process of design, fabrication and production must be considered. Aiming at SAW devices and theirs correlative circuits, the interference mechanism and interference immunity character are analyzed in this paper. This paper has built up equivalent models of the interference of external electromagnetic fields and coupling fields through an aperture to wires. Terminal induced voltage changes due to signal frequency are analyzed and calculated by transmission line theory and CAD simulation, which will enter SAW devices. Combining the external circuits character of SAWD and Y matrix, disturbed voltage of the SAWD export is derived. This paper also analyzes crosstalk coupling of SAWF down-leads by the coupling model between two parallel transmission lines. The total crosstalk coupling response to signal frequency is derived from analyzing the capacitance-coupling and inductance-coupling between parallel lines. Besides, this paper also analyze simply the reason bringing triple-transit-echo(TTE) and measure of reducing it. Finally we also use Remez exchange to design SAWF, which may improve the performance of SAWF. This paper meets the requirements of military and civil use. If this research work can be applied in future, it is a practical value to improve the stabilization and credibility of SAW device in complex electromagnetic circumstance.