A photodetector array for a one terabyte optical tape recorder

A 192-channel photodetector array analog/digital IC where each channel contains an integrated photodetector diode, a current-to-voltage amplifier, an optical threshold adjust circuit with differential sample and hole, and a comparator has been fabricated. The measured input referred noise current of the amplifier is less than 0.68 pA/(Hz)/sup 1/2/ with a signal bandwidth of at least 2.15 MHz and a supply current for one amplifier of only 185 mu A. The photodiode responsivity, the noise of the current-to-voltage amplifier, and the accuracy of the threshold adjust circuit with differential sample and hold were found to be better than system requirements.<
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