Linear LT5570 RF功率检测方案

Linear 公司的LT5570是 40MHz到2.7GHz的对数均方值 RF功率检测器，动态范围从–52dBm 到13dBm（和频率有关），线性动态范围高达 60dB。LT5570适合各种 RF标准，包括CDMA, W-CDMA, CDMA2000, TD-SCDMA 和WiMAX的精密RF功率测量和电平控制。本文介绍了LT5570的主要性能，应用电路以及应用测试电路图。

LT5570: 2.7GHz, 60dB Mean-Squared Power Detector Responds in 500ns
The LT®5570 is a 40MHz to 2.7GHz monolithic Logarithmic Mean-Squared RF power detector. It is capable of RMS measurement of an AC signal with wide dynamic range, from –52dBm to 13dBm depending on frequency. The power of the AC signal in an equivalent decibel-scaled value is precisely converted into DC voltage on a linear scale, independent of the crest factor of the waveforms. The LT5570 is suitable for precision RF power measurement and level control for a wide variety of RF standards, including CDMA, W-CDMA, CDMA2000, TD-SCDMA and WiMAX.
The DC output is buffered with a low output impedance amplifi er capable of driving a high capacitance load.
主要特性：
n Frequency Range: 40MHz to 2.7GHz
n Accurate RMS Power Measurement of High Crest
Factor Modulated Waveforms
n Linear DC Output vs Input Power in dBm
n Linear Dynamic Range: Up to 60dB
n Exceptional Accuracy over Temperature: ±0.3dB
n Fast Response Time: 0.5μs Rise Time,
8μs Fall Time
n Low Supply Current: 26.5mA
n Low Impedance Output Buffer Capable of Driving
High Capacitance Load
n Small 3mm 3mm 10-Lead DFN Package
主要应用：
n RMS Power Measurement
n RF Power Control
n Receive and Transmit Gain Control
n W-CDMA, CDMA2000, TD-SCDMA, WiMAX
n RF Instrumentation



图1。LT5570应用电路图



图2。40MHz 到 860MHz 应用时LT5570测试电路图