原标题：Linear LTC6946高性能低噪音5.7GHz PLL解决方案

　　Linear 公司的LTC6946是集成了VCO的高性能低噪音5.7GHz 锁相环(PLL)，包括基准电源分压器，带锁相指示器的锁相频率检测器(PFD)，超低噪音电荷泵，整数反馈除法器，VCO输出驱动器。归一化带内本底相位噪音-226dBc/Hz，归一化带内1/f噪音为 -274dBc/Hz,宽带输出相位噪音为-157dBc/Hz，主要用于无线基站(LTE, WiMAX, W-CDMA, PCS)，宽带无线接入，军用和安全无线电，测试测量。本文介绍了LTC6946主要特性，方框图，5.7GHz宽带接收器电路图和驱动调制器电路图。

　　The LTC®6946 is a high performance, low noise, 5.7GHz phase-locked loop (PLL) with a fully integrated VCO, including a reference divider, phase-frequency detector (PFD) with phase-lock indicator, ultralow noise charge pump, integer feedback divider, and VCO output divider. The charge pump contains selectable high and low voltage clamps useful for VCO monitoring.

　　The integrated low noise VCO uses no external components. It is internally calibrated to the correct output frequency with no external system support.

　　The part features a buffered, programmable VCO output divider with a range of 1 through 6, providing a wide frequency range.

　　LTC6946主要特性：

　　Low Noise Integer-N PLL with Integrated VCO

　　–226dBc/Hz Normalized In-Band Phase Noise Floor

　　–274dBc/Hz Normalized In-Band 1/f Noise

　　–157dBc/Hz Wideband Output Phase Noise Floor

　　Excellent Spurious Performance

　　Output Divider (1 to 6, 50% Duty Cycle)

　　Output Buffer Muting

　　Low Noise Reference Buffer

　　Charge Pump Current Adjustable from 250μA to 11.2mA

　　Configurable Status Output

　　SPI Compatible Serial Port Control

　　PLLWizard™ Software Design Tool Support

　　LTC6946应用：

　　Wireless Base Stations (LTE, WiMAX, W-CDMA, PCS)

　　Broadband Wireless Access

　　Military and Secure Radio

　　Test and Measurement

　　图1。LTC6946方框图

　　图2。LTC6946 5.7GHz宽带接收器电路图

　　图3。采用LTC6946-2驱动调制器电路图