Linear 公司的LTC6946是集成了VCO的高性能低噪音5.7GHz 鎖相環（PLL），包括基準電源分壓器，帶鎖相指示器的鎖相頻率檢測器（PFD），超低噪音電荷泵，整數反饋除法器，VCO輸出驅動器。歸一化帶內本底相位噪音-226dBc/Hz，歸一化帶內1/f噪音為-274dBc/Hz,寬帶輸出相位噪音為-157dBc/Hz，主要用于無線基站(LTE, WiMAX, W-CDMA, PCS)，寬帶無線接入，軍用和安全無線電，測試測量。本文介紹了LTC6946主要特性，方框圖，5.7GHz寬帶接收器電路圖和驅動調制器電路圖。

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應用：

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

Broadband Wireless Access

Military and Secure Radio

Test and Measurement


圖1。LTC6946方框圖

圖2。LTC6946 5.7GHz寬帶接收器電路圖

圖3。采用LTC6946-2驅動調制器電路圖

詳情清見：
http://cds.linear.com/docs/Datasheet/6946f.pdf