由于频率合成器特有的优越性是从一个高稳定度和准确度的标准频率产生无限多个同一稳定度和准确度的频率.因此在通讯、导航、雷达、电视、遥控遥测、现代化仪器仪表、全息照相、激光技术等方面的用途日益广泛.频率合成器目前有三种.1.直接式(加法式)2.锁相式3.数字式.前二种线路复杂,体积大,调试困难.随着中、大规模集成电路发展,特别是高速ECL集成电路的配套生产,为数字式频率合成器的研制提供了广阔前景.数字式频率合成器的特点是线路简单,调试方便、成本低廉、维修方便;但动态范围较小,因此用在某一个频段范围是十分合适的.本文介绍的频率合成器用于主被动锁模激光器,作为声光调制器的激励级.根据要求频率调节范围为20MH_z～60MH_z,频道间距10KH_z.装调后频率合 Because of the unique advantages of a frequency synthesizer, which is to generate an infinite number of frequencies of the same stability and accuracy from a standard frequency of high stability and accuracy, in modern applications such as communications, navigation, radar, television, telemetry, Hologram, laser technology, etc. The frequency synthesizer has three kinds: 1. Direct type (Addition type) 2. Phase-locked type 3. Digital type The first two kinds of circuits are complex, bulky and difficult to debug. The development of large-scale integrated circuits, especially high-speed ECL integrated circuits, provides a broad prospect for the development of digital frequency synthesizers.Digital frequency synthesizers are characterized by simple circuits, convenient debugging, low cost and maintenance Convenient, but the dynamic range is smaller, so it is very suitable to use in a certain range of frequency band.The frequency synthesizer introduced in this paper is used as active-active mode-locked laser as the excitation level of acousto-optic modulator.According to the requirement, the frequency adjustment range is 20MH_z ~ 60MH_z, channel spacing 10KH_z. After loading and adjusting the frequency together