A 1.25Gbps Laser Diode Driver with Programmed Temperature Compensation for Modulation Current

A 1.25 Gbps integrated laser diode driver (LDD) driving an edge-emitting laser is presented for optical-fiber communication applications. The IC can provide both modulation current (5 mA to 85 mA) with temperature compensation adjustments to minimize the variation in extinction ratio, and independent bias current (4 mA to 100 mA) with automatic power control. This paper firstly proposes a novel circuit called temperature-dependent current switch (TDCS) technique to implement temperature compensation for modulation current. Moreover, programmed by choice of external resistors Rtcstart and Rtcslope, the range of modulation current temperature coefficient can be adjusted from 400 ppm/degC to 2times10⁴ ppm/degC and the range of programmable temperature at which modulation current compensation starts can be adjusted from 20 degC to 75 degC, which results in the IC to suit the need of different characteristics in different laser diode. The chip is implemented in a 0.35 mum BiCMOS technology and occupies an area of 1.61x1.66 mm² with power consumption of 95 mW from a supply voltage of 3.3 V