TRANSMISSION RECEPTION CHANGEOVER SYSTEM FOR LASER DIODE TRANSCEIVER

摘要

PURPOSE:To improve the signal reception characteristic by decreasing a discharge current negligibly smaller than a signal current without deterioration in the transmission efficiency and limit of a transmission available range. CONSTITUTION:A switch SW1 is controlled to be OFF and a switch SW2 is to be ON in the transmission mode and a transmission signal is modulated directly at a transistor(TR). The TR is turned off (at a cut-off region) at the end of transmission. The switch SW1 is controlled to be ON and the switch SW2 is to be OFF for a time Tb before the transit to the reception mode. Thus, a laser diode LD is reverse-biased by a power supply Vr via a resistor Rs for the time Tb. The switch SW1 is restored to be OFF and the switch SW2 is to be ON after the time Tb and a received current flows through a resistor R1 (in the reception mode).