Linear公司的LTC5569是雙路有源下變換混頻器,每個混頻器包括單獨的LO緩沖放大器,有源混頻器核,以及帶使能引腳的偏壓電路.1950MHz時的IIP3高達26.8dBm,變換增益2dB,1950MHz的噪音為11.7dB,通路間的隔離度為44dB,總功耗為3.3V/600W,主要用在無線接收器,MIMO接收器和遙控無線電單元.本文介紹了LTC5569主要特性, 方框圖, 多用途接收器電路圖以及低通和高通IF輸出匹配電路圖,測試電路和評估板布局圖.

The LTC®5569 dual active downconverting mixer is optimized for diversity and MIMO receiver applications that require low power and small size. Each mixer includes an independent LO buffer amplifier, active mixer core, and bias circuit with enable pin. The symmetry of the IC assures that a phase and amplitude coherent LO is applied to each mixer.

The RF inputs are 50Ω matched from 1.4GHz to 3.3GHz, and easily matched for higher or lower RF frequencies with simple external matching. The LO input is 50Ω matched from 1GHz to 3.5GHz, even when one or both mixers are disabled. The LO input is easily matched for higher or lower frequencies, as low as 350MHz, with simple external matching. The low capacitance differential IF outputs are usable up to 1.6GHz.

LTC5569主要特性：

High IIP3: 26.8dBm at 1950MHz

2dB Conversion Gain

Low Noise Figure: 11.7dB at 1950MHz

17dB NF Under 5dBm Blocking

44dB Channel Isolation

Low Power: 3.3V/600mW Total

Very Small Solution Size

Enable Pins for Each Mixer

Wide IF Frequency Range

LO Input 50Ω Matched in All Modes

–40℃ to 105℃ Operation

16-Lead (4mm × 4mm) QFN package

LTC5569應用：

Wireless Infrastructure Diversity Receivers

MIMO Infrastructure Receivers

Remote Radio Units

圖1.LTC5569方框圖

圖2.LTC5569 190MHz通帶IF匹配的多用途接收器電路圖

圖3.LTC5569 200歐姆低通IF輸出匹配電路圖(所示元件為190MHz IF)

圖4.LTC5569 200歐姆高通IF輸出匹配電路圖(所示元件為190MHz IF)

圖5.LTC5569 測試電路圖

圖6.LTC5569評估板布局圖
詳情請見:
http://cds.linear.com/docs/Datasheet/5569f.pdf