摘 要：调幅发射机目前正广泛应用于无线电广播系统中，课题以电子线路课程设计实践为背景，通过查阅大量教学文献，并结合专业基础课程教学需要，以原教学内容为基础，完成了小功率调幅发射机从设计、仿真到安装、调试等一系列完整设计工作。

　　　发射机的主要任务是完成有用的低频信号对高频载波的调制，将其变为在某一中心频率上具有一定带宽、适合通过天线发射的电磁波。

　　　所谓调幅，就是指使振幅随调制信号的变化而变化，严格的讲，就是指载波振幅与调制信号的大小成线性关系，而它的频率和相位不变。振幅调制分为4种方式：AM（普通调幅）、DSB（抑制载波双边带调幅）、SSB（单边带调幅）、VSB（残留边带调幅）。本设计调幅发射机指的是AM调幅发射机。

　　　文中系统的设计了振荡器、音频放大器、振幅调制器和谐振功率放大器等系统单元电路，并通过具有射频仿真模块的软件Mμltisim，试验和仿真优化了系统电路。

关键词：调幅发射机；振荡器；音频放大器；调幅调制器；功率放大器

Abstract：AM transmitters are now widely used in radio broadcasting systems， this thesis as the background of electronic circuit，Through access to a large number of teaching literature, combined with teaching needs, based on the original teaching, completed the low-power AM transmitters from the design, simulation to the installation and commissioning of a full range of design work.  

　　The main task of the transmitter is complete the useful signal frequency modulated high frequency carrier. to turn it into a center frequency at a certain bandwidth, suitable for electromagnetic waves emitted by the antenna.

　　The so-called spinodal means make the amplitude with the modulation signal changes, strictly speaking, refers to the carrier amplitude modulated with signal size linearly, but its frequency and phase constant. Amplitude modulation is divided into 4 ways: AM ( amplitude ), DSB ( bilateral with carrier suppression modulation ), SSB ( single sideband modulation ), VSB ( VSB ). The design of AM transmitters is referred to as AM am transmitter.

　　Oscillator, audio amplifier, power amplifier and resonant amplitude modulator is designed by the system using software Multisim circuit simulation and optimization of the system.

Key words：Low-power AM transmitters; Oscillator; Audio amplifier; Amplitude Modulator; Power amplifier.