Analog Devices' new ADL5310 dual logarithmic converter offers the functionality of two discrete converters on a single chip, providing designers of optical communication systems an alternative to using multiple individual logarithmic converters. The ADL5310 operates from a single supply as low as 3 V, and converts input current over a 100-dB dynamic range. It is housed in a space-efficient 24-pin LFCSP (lead-frame chip-scale package) for increased board space savings.
The ADL5310 contains two independent signal channels for photodiode interfacing. This flexible design allows the transfer function constants (slope and intercept) to be individually configured for each channel. In addition, the internal bias circuitry is shared between the two channels for improved power consumption and channel matching. The ADL5310 simplifies the design of control loops for erbium-doped fiber amplifiers (EDFA), variable optical attenuators (VOA), and optical add/drop multiplexers (OADM), as its log transformation allows the measurement signals to be differenced to compute the gain or absorbance across a network element. Traditional solutions require more expensive digital signal processing with switched-gain trans-impedance amplifier front-ends.
The ADL5310 is optimized for power monitoring in a wide-range of optical communication system applications, including laser-control circuitry, optical switches, attenuators, amplifiers, and general system monitoring. General-purpose applications for the ADL5310 include log-ratio signal compression, absorbance and gain measurements, multi-channel optical power measurements, and wide-range baseband log-compression.
The ADL5310 is available in a 4 x 4 mm, 24-pin LFCSP and is specified for operation from -40 degrees C to +85 degrees C. The part is priced at $11.33 per unit in 1,000-piece quantities.