Master-slice monolithic integration design and characteristics of LD/LED transmitters for 100-400 mbit/s optical transmission systems

Monolithic integration of LD and LED transmitters operating at 100-400 Mbit/s is investigated using a 3-μm Si-bipolar process as a first step in the establishment of a master-slice IC technology for optical communication systems. An LD transmitter IC is developed as a master IC, which includes a differential current switch and an input buffer circuit for high-speed modulation and a current stabilizer and an APC circuit for the stabilization of the output optical power, An LED transmitter is fabricated by the minor change of wiring of the master IC. The former exhibits 0.5-ns rise and 0.7-ns fall times at the signal current of 40 mA. Also the latter exhibits 0.4-ns rise and 0.6-ns fall times at the signal current of 100 mA. Characteristics of LD and LED transmitters are estimated in order to prove the usefulness of the fabricated IC's. As a result, it is confirmed that both transmitters using the fabricated IC's operate at the modulation speed of 300-400 Mbit/s and output optical power fluctuations of less than ±0.5 dB over the ranges of 5V ±5 percent supply voltage and 0-50°C temperature. From these results, it is proven that the master-slice monolithic integration is feasible and will be very useful for reduction of the turn-around time in IC development.