AD641

a 250 MHz Demodulating Logarithmic Amplifier AD641 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 ␮V Input Offset Voltage Low Power ؎5 V Supply Operation 9 mA (+VS), 35 mA (–VS) Quiescent Current Onboard Resistors Onboard 10؋ 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 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 sin...