Design of 2.5Gb/s CMOS optical transceiver array

Abstract

We describe design of 2.5Gb/s CMOS optical transceiver array using 0.35 mm CMOS technology. The transceiver array consists of Laser Diode (LD) driver and limiting amplifier with current decision circuit. CMOS LD driver offers the capability of independent DC and modulation current adjustments. The DC component used to pre-bias the LD is adjustable at a range of 0~30 mA. Optical receiver consists of current decision circuit with voltage output buffer. Optical receiver allows wide dynamic range of input current. The decision circuit uses positive feedback from the cross-gate connection of two NMOSs to increase the gain of the decision element, while the output buffer convert the output of the decision circuit into a logic signal(i.e., 0 or 3.3V). With this design technique, we have succeeded in developing a CMOS optical transceiver array with high performance.