成 都 信 息 工 程 学 院学 位 论 文电视 RF-AV 转换电路的设计电视 RF-AV 转换电路的设计摘 要本文介绍了将电视射频信号转换为音视频信号的工作原理。利用 TDQ-3 型全增补调谐器、声表面滤波器、中频处理芯片 TA7680AP 和 LM386 集成运算放大器设计了一个电视 RF-AV 转换电路。天线接收的空间电视 RF 信号输入高频调谐器，经高频滤波、放大、调谐、变频等电路处理后，将电视 RF 信号转换成38MHz 第一中频信号，第一中频信号由声表面滤波器进行残留边带滤波后送入中频处理芯片 TA7680AP，最后经检波、解调后输出音视频信号。设计的 RF-AV 转换电路接收频率范围 45MHz～860MHz，输出视频 1VP-P，阻抗 75Ω，音频输出 0dbm，阻抗 600Ω，具有自动增益控制（ AGC）和自动频率微调（AFT）功能。给出了电视 RF-AV 转换电路、DC32V 和 DC12V 供电电源的电路设计原理图，完成了样机 PCB 板的设计，制作了样机并对样机进行了调试和检测。关键词：射频；调谐器；声表面滤波器；TA7680；中频处理The design of the radio frequency converting to the audio frequency and the video frequencyAbstractThis paper introduces the principle of the radio frequency converting to the audio frequency and the video frequency. The circuit of RF-AV Conversion has been designed using all added tuner TDQ-3, surface acoustic wave filter, IF TA7680AP chip and Integrated Operational Amplifier LM386. Space television RF signal received by antenna is inputted into high-frequency turner. After high frequency filter, amplification, Tuner, frequency conversion and so on electric circuit processing, television RF signal transforms into the first intermediate frequency signal whose frequency is 38MHz. the first intermediate frequency signal which Carries on the vestigal sideband filter by the sound surface filter, Then, sent them into IF TA7680AP chip, the last by the detector, the output audio and video post-demodulation signal. The design of RF-AV conversion circuit to receive the frequency ran...
