ADI ADL5336帶可編RMS檢測器的IF VGA解決方案

發布時間：2011-9-29 15:45 發布者：Liming

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