基于LT5527的400MHz至3.7GHz高信号电平下变频混频器电路设计

字数:6127,页数:23

摘 要
   简要介绍LT5527有源混频器的特点、应用与典型应用、绝对最大额定值、封装与引脚功能、DC电特性、AC电特性、典型AC性能特性、典型DC性能特性、测试电路与应用信息。LT5527 有源混频器专为高线形度、宽动态范围下变频器应用而优化。该IC包括一个用于驱动双平衡混频器的高速差分LO缓冲放大器。RF和LO输入端上的宽带、集成变压器提供了单端50Ω接口。差分IF输出可提供至差分IF滤波器和放大器的便利连接，也可轻松地实现匹配以驱动50Ω单端负载（采用或不采用外部变压器均可）。LT5527的高集成度最大限度地减少了总体解决方案的成本、电路板占用空间和系统级偏差。
关键字：转换增益  RF输入
  LO输入  IF输出  AC电特性

Abstract
   It briefly introduced the features,application and typical application,absolute maximum ratings,package and pin functions, DC electrical characteristics ,AC electrical characteristics ,typical AC performance characteristics, typical DC performance characteristics,test circuits and applications information of The LT5527 active mixer. The LT 5527 active mixer is optimized for high linearity,wide dynamic range downconverter applications. The ICincludes a high speed differential LO buffer amplifier driving a double-balanced mixer. Broadband, integrated transformers on the RF and LO inputs provide singleended 50? interfaces. The differential IF output allows convenient interfacing to differential IF filters and amplifiers,or is easily matched to drive 50? single-ended, with or without an external transformer. The LT5527’s high level of integration minimizes the total solution cost, board space and system-level variation.
Key word:  Conversion Gain   RF Input 
LO Input   IF Output  AC Electrical Characteristics

                         　　　目 录

LT5527芯片简介.....................................................................4
１.１　特点........................................................................4
１.２　应用........................................................................4
１.２.１　典型应用.................................................................4
    １.３　绝对最大额定值..........................................................5
2. LT5527芯片封装与引脚功能........................................................5
２.１　封装........................................................................5
２.２　封装描述....................................................................6
２.３　引脚功能....................................................................6
3. LT5527内部结构与工作原理........................................................7
    ３.１　LT5527内部结构方框图....................................................7
    ３.２　LT5527的工作原理........................................................7
３.２.１　DC电特性.................................................................７
３.２.２　AC电特性.................................................................8
３.２.３　AC电特性　标准下变频器应用...............................................8
３.２.４　典型AC性能特征...........................................................9
中间频段（无外部RF／LO匹配.........................................................9
高频段（采用外部RF匹配的3500MHz应用...............................................11
低频段（采用外部RF／LO匹配的450MHz应用）..........................................11
低频段（采用外部RF／LO匹配的900MHz应用）..........................................11
３.２.５　典型DC性能特征..........................................................12
４. LT5527应用电路设计............................................................12
４.１　测试电路原理图.............................................................12
　４.１.１　下混频器测试原理图――标准IF匹配(240MHz IF)...........................12
　　　４.１.２　下混频器测试原理图――分立型IF平衡-不平衡转换器匹配(240MHz IF)....13
　　　４.１.３　对上面两图可使用两种评价板........................................13
　　４.２　RF输出端口.............................................................14
　　４.３　LO输入端口.............................................................16
　　４.４　IF输出口...............................................................17
　　　4.4.1  直接8：1IF变压器匹配.................................................18
　　　4.4.2  低通+4：1IF变压器匹配................................................18
　　　4.4.3  分立型IF平衡-不平衡转换器匹配........................................19
５. 总结..........................................................................22
参考文献..........................................................................23