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Linear公司的LTC5569是300MHz-4GHz頻段雙路有源下變換混頻器,1950MHz時(shí)的IIP3為26.8dBm,噪音為11.7dB,變換增益為2dB,通路間隔離為44dB,3.3V的總功耗為600mW,主要用在無線基礎(chǔ)設(shè)備分集接收器,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, 下變換器測試電路圖以及多種應(yīng)用電路. LTC5569 300MHz to 4GHz 3.3V Dual Active Downconverting Mixer 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(yīng)用: Wireless Infrastructure Diversity Receivers MIMO Infrastructure Receivers Remote Radio Units 
圖1. LTC5569方框圖
圖2. LTC5569下變換器測試電路圖(190MHz帶通IF匹配)
圖3. LTC5569 190MHz帶通IF匹配分集接收器電路圖
圖4. LTC5569評估板布局圖
圖5. LTC5569帶通匹配和8:1變壓器的IF輸出電路圖
圖6. LTC5569寬帶匹配和4:1變壓器的IF輸出電路圖
圖7. LTC5569分立IF平衡/不平衡變壓器匹配電路圖
圖8. LTC5569 200歐姆差分低通IF輸出匹配電路圖(所示元件值對應(yīng)于190MHz IF) 詳情請見: 
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