Linearization of optoisolators

Existing single-loop feedback methods of linearization do not consider the conflicting aspect of linearity and longer lifetime of the LED's. In this correspondence, a multiple-loop feedback system is proposed in which the biasing current of the LED is as low as 2 mA. This multiple-loop arrangement has the property of zero-sensitivity system and the system gain is independent of the parameters of the system. The gain is given by the ratio of two resistors. The method avoids the use of slew rate limited operational amplifiers.