ADL5303ACPZ-R7 (ANALOG DEVICES)

The ADL5303ACPZ-R7 is a monolithic Logarithmic Detector optimized for the measurement of low frequency signal power in fibre optic systems and offers a large dynamic range in a versatile and easily used form. Wide measurement range and accuracy are achieved using proprietary design and precise laser trimming. The ADL5303 requires only a single positive supply, VPS, of 5V. When using low supply voltages, the log slope can be altered to fit the available span. Low quiescent current and chip disable facilitate use in battery-operated applications. The input current, IPD, flows in the collector of an optimally scaled NPN transistor, connected in a feedback path around a low offset JFET amplifier. The current summing input node operates at a constant voltage, independent of current, with a default value of 0.5V, this may be adjusted over a wide range. An adaptive biasing scheme is provided for reducing photo-diode dark current at very low light input levels.