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ADI公司的ADL5336是帶可編RMS檢測器的中頻(IF)可編增益放大器( VGA),具有dB線性增益控制,工作頻率從低頻到1GHz,VGA和AGC工作模式,連續增益控制范圍48dB,最大增益時的噪音(NF)為6.8dB,1.0V輸出時的IMD3大于62dBc,單電源5V工作,主要用在點對多點無線電,儀表和醫療電子.本文介紹了方框圖,VGA1和VGA2功能框圖, 基本連接電路圖以及評估板電路圖,材料清單和元件布局圖. ADL5336 : Cascadable IF VGAs with Programmable RMS Detectors The ADL5336 consists of a pair of variable gain amplifiers (VGAs) designed for cascaded IF applications. The amplifiers have linear-in-dB gain control and operate from low frequencies to 1 GHz. Their excellent gain conformance over the control range and flatness over frequency are due to Analog Devices, Inc., patented X-AMP® architecture, an innovative technique for implementing high performance variable gain control. Each VGA has 24 dB of gain control range. Their maximum gain can be independently programmable over a 6 dB range via the SPI. The VGAs can be cascaded to provide a total range of 48 dB. When connected to a 50 Ω source through a 1:4 balun, the gain is 6 dB higher. The second VGA has an SPI programmable input switch that selects one of two external inputs. When driven from a 200 Ω source or from a 50 Ω source through a 1:4 balun, the noise figure (NF) for the composite amplifier is 6.8 dB at maximum gain. The output of each VGA can drive 100 Ω loads to 5 V p-p maximum. Each VGA has an independent square law detector for autonomous, automatic gain control (AGC) operation. Each detector setpoint can be programmed independently through the SPI from −24 dBV to −3 dBV in 3 dB steps. When both VGAs are arranged in AGC mode and are programmed to the same setpoint, the composite NF increases to 9 dB when backed off by 18 dB from maximum gain. The ADL5336 operates from a 5 V supply and consumes a typical supply current of 80 mA. When disabled, it consumes 4 mA. It is fabricated in an advanced silicon-germanium BiCMOS process and is available in a 32-lead exposed paddle LFCSP package. Performance is specified over a −40°C to +85°C temperature range. ADL5336主要特性: Pair of VGAs with rms AGC detectors VGA and AGC modes of operation Continuous gain control range: 48 dB Noise figure (NF) = 6.8 dB at maximum gain IMD3 > 62 dBc for 1.0 V p-p composite output Differential input and output Multiplexed inputs for VGA2 Programmable detector AGC setpoints Programmable VGA maximum gain Power-down feature Single 5 V supply operation ADL5336應用: Point-to-multipoint radios Instrumentation Medical 
圖1.ADL5336方框圖
圖2. VGA1功能方框圖
圖3. VGA2功能方框圖
圖4.ADL5336基本連接電路圖
圖5.ADL5336評估板電路圖 評估板材料清單(BOM):
圖6.ADL5336評估板元件布局圖 詳情請見: 
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