PRODUCT DESCRIPTION
The AD641 is a 250 MHz, demodulating logarithmic amplifier with an accuracy of ±2.0 dB and 44 dB dynamic range. The AD641 uses a successive detection architecture to provide an output current that is logarithmically proportional to its input voltage. The output current can be converted to a voltage using one of several on-chip resistors to select the slope. A single AD641 provides up to 44 dB of dynamic range at speeds up to 250 MHz, and two cascaded AD641s together can provide 58 dB of dynamic range at speeds up to 250 MHz. The AD641 is fully stable and well characterized over either the industrial or military temperature ranges.

FEATURES
    Logarithmic Amplifier Performance
        Usable to 250 MHz
        44 dB Dynamic Range
        ±2.0 dB Log Conformance
        37.5 mV/√dB Voltage Output
        Stable Slope and Intercepts
    2.0 nV/√Hz Input Noise Voltage
    50 μV Input Offset Voltage
    Low Power
        ±5 V Supply Operation
        9 mA (+VS), 35 mA (–VS) Quiescent Current
    Onboard Resistors
    Onboard 10x Attenuator
    Dual Polarity Current Outputs
    Direct Coupled Differential Signal Path
   
APPLICATIONS
    IF/RF Signal Processing
    Received Signal Strength Indicator (RSSI)
    High Speed Signal Compression
    High Speed Spectrum Analyzer
    ECM/Radar