基于LT5572的芯片简介及应用电路设计

字数:4606,页数:16

摘要
简要介绍高频线性直接积分调制器LT5572的功能、内部结构、引脚排列及典型的应用电路。LT5572 是为高频无线应用而设计的直接I/Q 调节器, 包括无线电系统内各部分. 它允许用微分的基带I/Q信号直接调制射频信号。它支持PHS,GSM,EDGE,TD-SCDMA,CDMA,CDMA2000      W-CDMA和其他的系统。它也可能是被形成映象通过申请对I/Q输入信号的90°移相抵制混频器。 I/Q基带输入的高频阻抗由用来转向驱动双平稳的混频器的电压电流转换器组成。 这些混频器的输出被总计和应用到一个在芯片上的射频变压器，这个变压器能把微分混频信号转换成一个50 的单端输出信号. 第四个平稳的I/Q基带输入端口是为来自一个源头的直流耦合而故意设定的，这个源头带有0.5v左右的模拟电压.LO通道由一个带有单端输入信号的LO缓冲器和为这些混频器产生LO驱动的精密积分发生器所组成。供应电压范围是4.5v到5.25v。
关键字： 调制器  混频器   缓冲器    积分发生器
 

Abstract
It briefly introduced 1.5GHz to 2.5GHz High Linearity Direct Quadrature Modulator function, internal structure, pin array and typical apply circuit. The LT5572 is a direct I/Q modulator designed for high performance wireless applications, including wireless infrastructure. It allows direct modulation of an RF signal using differential baseband I and Q signals. It supports PHS,GSM, EDGE, TD-SCDMA, CDMA, CDMA2000, W-CDMA and other systems. It may also be confi gured as an image reject up-converting mixer by applying 90° phase-shifted signals to the I and Q inputs. The high impedance I/Q baseband inputs consist of voltage-to-current convertersthat in turn drive double-balanced mixers. The outputs ofthese mixers are summed and applied to an on-chip RF transformer which converts the differential mixer signals to a 50Ω single-ended output. The four balanced I and Q baseband input ports are intended for DC coupling from a source with a common mode voltage level of about 0.5V. The LO path consists of an LO buffer with single-ended input and precision quadrature generators that produce the LO drive for the mixers. The supply voltage range is 4.5V to 5.25V.

Key word: Modulator    Mixer    Buffer    Quadrature Generator

目 录
1. LT5572芯片简介---------------------------------------------4
2. LT5572芯片封装与引脚功能-----------------------------------4
3. LT5572内部结构与工作原理-----------------------------------5
 3．1 内部结构图-----------------------------------------------5
 3．2 功能描述-------------------------------------------------5
  3．2．1 基带界面---------------------------------------------5
  3．2．2  LO部分----------------------------------------------7
  3．2．3  RF部分----------------------------------------------8
 3.3  电气特性-------------------------------------------------10
4. 基于LT5572变换发射机的应用电路设计-------------------------11
5. 总结--------------------------------------------------------15
参考文献-------------------------------------------------------16

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