Low input resistance transimpedance optical preamplifier for fibre optic local area networks

The authors describe a bipolar transimpedance optical preamplifier utilizing a common-base input stage that exhibits certain advantages over more conventional design using common-emitter or common-collector input stages and is suitable for monolithic integration. Monolithic fabrication of the circuit will enable a bandwidth of greater than 200 MHz to be achieved. The low input impedance of the common-base configuration enables optimum performance to be maintained with lower cost photodiodes exhibiting a moderate capacitance in the 2-6 pF range. The approach is particularly suitable for cost-sensitive high-speed fiber-optic local area network formulations such as the emerging fiber distributed data interface (FDDI) specification.<>