US Patent 10594405 Optical receiver and method of controlling optical receiver

In an optical receiver, a control unit determines an SOA current set value such that an SOA current becomes a maximum value ISOA_MAXwhen a VOA voltage is smaller than a first threshold value VVOA_LOW, determines the SOA current set value such that the SOA current becomes smaller than the maximum value ISOA_MAX and larger than a minimum value ISOA_MIN when the VOA voltage is equal to or larger than the first threshold value VVOA_LOW and is smaller than a second threshold value VVOA_HIGH, and determines the SOA current set value such that the SOA current is fixed to the minimum value ISOA_MIN when the VOA voltage is equal to or larger than the second threshold value VVOA_HIGH.