The LT1319 is a general purpose building block that contains all the circuitry necessary to transform modulated photodiode signals back to digital signals. The circuit's flexibility permits it to receive multiple modulation methods. A low noise, high frequency preamplifier performs a current-to-voltage conversion while rejecting low frequency ambient interference with an AC coupling loop. Two separate high impedance filter buffer inputs are provided so that off-chip filtering can be tailored for specific modulation schemes. The filter buffers drive separate differential gain stages that end in comparators with internal hysteresis. The comparator thresholds are adjustable externally by the current into Pin 11. One channel has a high speed 25ns comparator required for high data rates. The second channel's comparator has a 60ns response time and is well suited to more modest data rates. A power saving shutdown feature is useful in portable applications.