摘 要
在高频电子线路中，振幅调制、同步检波、混频、倍频、鉴频等调制与解调的过程均可视为两个信号相乘的过程，而集成模拟乘法器正是实现两个模拟量，电压或电流相乘的电子器件。采用集成模拟乘法器实现上述功能比用分立器件要简单得多，而且性能优越，因此集成模拟乘法器在无线通信、广播电视等方面应用较为广泛。
混频器在通信工程和无线电技术中，应用非常广泛，在调制系统中，输入的基带信号都要经过频率的转换变成高频已调信号。在解调过程中，接收的已调高频信号也要经过频率的转换，变成对应的中频信号。特别是在超外差式接收机中，混频器应用较为广泛，混频电路是应用电子技术和无线电专业必须掌握的关键电路。 Multisim10是属于新一代的电子工作平台，是一种电子技术界广泛应用的优秀计算机仿真软件。
主要内容是基于MC1496的混频器应用设计与仿真，阐述混频器基本原理，并在电路设计与Multisim仿真环境中创建集成电路乘法器MC1496电路模块，利用模拟乘法器MC1496完成各项电路的设计与仿真，并结合双踪示波器实现对信号的混频，对接收信号进行频率的转换,变成需要的中频信号。
关键词：MC1496乘法器；混频器；Multisim
Abstract
In high frequency electronic circuit course, amplitude modulation,synchronization demodulation, mixer, frequency, frequency modulation and demodulation are regarded as the process of the two signals are multiplied, and the integrated analog multiplier is the realization of two analog electronic device, a voltage or current multiplication. The integrated analog multiplier to achieve the above functions than discrete devices are much more simple, and superior performance, therefore the integrated analog multiplier is widely used in wireless communications, radio and television broadcasting.
The mixer in communication engineering and radio technology,application is very extensive, in modulation system, the input of baseband signal are through frequency conversion into a high frequency modulated signal. In the demodulation process, the received modulated high frequency signal after frequency conversion, into intermediate frequency signals corresponding to. Especially in the superheterodyne receiver, mixer is widely used, mixing circuit is the key module of Applied Electronic Technology and professional radio must master.
Multisim10 is a new generation of electronic platform belongs to, is an excellent computer widely used an electronic technology field simulation software.
The main content is the mixer application design and simulation based on MC1496, expounds the basic principle of mixer, and the circuit design and Simulation in Multisim environment to create integrated circuit MC1496 multiplier circuit module, the analog multiplier MC1496 to complete the design and Simulation of the circuit, and combined with the dual trace oscilloscope to achieve signal mixing, the switching frequency of the received signal the intermediate frequency signal, a need.
Key Words：MC1496 multiplier; mixer; Multisim
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目 录
摘 要 .......................................................................................................... 1 Abstract ............................................................................................................ II 引 言 .......................................................................................................... 1 1.方案分析 ........................................................................................................ 2 2.单元电路的工作原理 ..................................................................................... 4 2.1 LC正弦波振荡器 .................................................................................. 4 2.2 模拟乘法器电路 .................................................................................... 6 2.3 选频﹑放大电路 .................................................................................... 8
3.电路性能指标的测试 ..................................................................................... 9 结 论 ........................................................................................................ 11 致 谢 ........................................................................................................ 12 参 考 文 献 ................................................................................................... 13
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辽宁工程技术大学硕士学位论文
引 言
混频技术应用的相当广泛，混频器是超外差接收机中的关键部件。直放式接收机是高频小信号检波，工作频率变化范围大时，工作频率对高频通道的影响比较大（频率越高，放大量越低，反之频率低，增益高），而且对检波性能的影响也较大，灵敏度较低。采用超外差技术后，将接收信号混频到一固定中频，放大量基本不受接收频率的影响，这样，频段内信号的放大一致性好，灵敏度可以做得很高，选择性也较好。因为放大功能主要放在中放，因此可以用良好的滤波电路。采用超外差接收后，调整方便，放大量﹑选择性主要由中频部分决定，且中频较高频信号低，性能指标容易得到满足。混频器在一些发射设备中也是必不可少的。在频分多地址信号的合成、微波接力通信、卫星通信等系统中也有其重要地位。此外，混频器也是许多电子设备、测量仪器（如频率合成器、 频谱分析仪等）的重要组成部分。
混频器是频谱线性搬移电路，能够将输入的两路信号进行混频。具体原理框图如图1所示。
振荡器输出一频率为f1=10MHz、幅值0.2V＜U1m＜1V的正弦波信号，此信号作为混频器的第一路输入信号；高频信号源输出一正弦波信号，f2=10MHz、幅值
U2m=200mV，此信号作为混频器的第二路信号，将这两路信号作为模拟乘法器的输入进行混频。选频放大电路则对混频后的信号进行选频、放大，最终输出2MHz的正弦波信号。
正弦波 模拟 选频、放大 高频
图1 混频器原理框图
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