The Study Of TV-IF SAWF Design And Compensation For SAWF Second-order Effects

Progress in the communication industry has led to an increasing need for SAW filters.Traditional impulse response method can design and analysis the SAW device. With the development of stereo TV and high-definition television(HDTV),an improvement in filter performance becomes necessary.Some second order effects such as diffraction and Triple Transmit Signal(TTS)must be compensated strictly.In this article,the design of SAW-TV-IF filter is discussed.The diffraction and Triple Transmit Signal(TTS)effect are analyzed and the diffraction effect is compensated in order to increase the stop band attenuation and suppress signals of adjacent frequency channels.Firstly,the article introduces the basic principles of interdigital transducer and SAW filter.On this foundation the design method of a basic SAW filter is discussed.An example of designing a SAW-TV-IF filter is intrduced using the Remez exchange algorithm,and a SAW-TV-IF filter is designed,the center frequency of which is 37MHz.The ideal frequency response is analyzed and simulated.The diffraction effect in SAW filters is described and analysed.We calculated the effects of diffraction of the SAW filter in both the frequency and time domains to correct the aperture so that the diffracted frequency response is close to the desired response.The frequency response with diffraction is simulated.Then we contrast and analyze the corrected and uncorrect IDT results in detail.The SAW-TV-IF filter is compensated and the frequency after compensation is simulated.Then the affect of triple transmit signal(TTS)is analysed using the equivalent circuit model,and the frequency response with TTS effect is simulated.Besides,this paper also analyze simply the reason bringing Body Acoustic Wave(BAW),Electrode Reflection measure of reducing them.