OPTICAL TRANSMITTER AND CIRCUIT AND METHOD FOR COMPENSATING THIRD-ORDER MUTUAL MODULATING DISTORTION SUITABLE FOR SAME

摘要

PURPOSE:To enable mass production by reducing thrid-order mutual modulating distortion to be generated by a light emitting element with more simplified configuration at a direct modulating system analog optical transmitter. CONSTITUTION:The inputted electric signal of a radio frequency is branched into two parts by a branching circuit 1, and a second-order mutual modulating distortion component is generated by a distortion generating circuit 14. A differential frequency component is extracted from that component by a low-pass filter 15 and synthesized by a synthesizing circuit 6 and afterwards, a light emitting element 17 is directly modulated. Corresponding to the setting of the gain of a level control circuit 16 and the delay of a delay control circuit 13, the third-order mutual modulating distortion of the light emitting element 17 is compensated while using the second-order mutual modulating distortion component of the differential frequency extracted by the low--pass filter 15.